Difference: TWikiPlugins (1 vs. 36)

Revision 362011-06-06 - TWikiContributor

 

TWiki Plugins

Add functionality to TWiki with readily available plugins; create plugins based on APIs

Overview

You can add plugins to extend TWiki functionality, without altering the core code. A plug-in approach lets you:

  • add virtually unlimited features while keeping the main TWiki code compact and efficient;
  • heavily customize an installation and still do clean updates to new versions of TWiki;
  • rapidly develop new TWiki functions in Perl using the plugin API.

Everything to do with TWiki plugins - demos, new releases, downloads, development, general discussion - is available at TWiki.org, in the TWiki:Plugins web.

TWiki plugins are developed and contributed by interested members of the community. Plugins are provided on an 'as is' basis; they are not a part of TWiki, but are independently developed and maintained.

Relevant links on TWiki.org:

See other types of extensions: TWikiAddOns, TWikiContribs, TWikiSkins

Installing Plugins

Each TWiki plugin comes with its own documentation: step-by-step installation instructions, a detailed description of any special requirements, version details, and a working example for testing. Many plugins have an install script that automates these steps for you.

Special Requirements: Some plugins need certain Perl modules to be preinstalled on the host system. Plugins may also use other resources, like graphics, other modules, applications, and templates. You should be able to find detailed instructions in the plugin's documentation.

Each plugin has a standard release topic, located in the TWiki:Plugins web at TWiki.org. There's usually a number of other related topics, such as a developers page, and an appraisal page.

On-Site Pretesting

The recommended approach to testing new plugins before making them public is to create a second local TWiki installation, and test the plugin there. You can allow selected users access to the test area. Once you are satisfied that it won't compromise your main installation, you can install it there as well.

InstalledPlugins shows which plugins are: 1) installed, 2) loading properly, and 3) what TWiki:Codev.PluginHandlers they invoke. Any failures are shown in the Errors section. The %FAILEDPLUGINS% variable can be used to debug failures. You may also want to check your webserver error log and the various TWiki log files.

Some Notes on Plugin Performance

The performance of the system depends to some extent on the number of plugins installed and on the plugin implementation. Some plugins impose no measurable performance decrease, some do. For example, a Plugin might use many Perl libraries that need to be initialized with each page view (unless you run mod_perl). You can only really tell the performance impact by installing the plugin and by measuring the performance with and without the new plugin. Use the TWiki:Plugins.PluginBenchmarkAddOn, or test manually with the Apache ab utility. Example on Unix:
time wget -qO /dev/null /twiki/bin/view/TWiki/AbcPlugin

TIP If you need to install an "expensive" plugin, but you only need its functionality only in a subset of your data, you can disable it elsewhere by defining the %DISABLEDPLUGINS% TWiki variable.

Define DISABLEDPLUGINS to be a comma-separated list of names of plugins to disable. Define it in Main.TWikiPreferences to disable those plugins everywhere, in the WebPreferences topic to disable them in an individual web, or in a topic to disable them in that topic. For example,

   * Set DISABLEDPLUGINS = SpreadSheetPlugin, EditTablePlugin

Managing Installed Plugins

Some plugins require additional settings or offer extra options that you have to select. Also, you may want to make a plugin available only in certain webs, or temporarily disable it. And may want to list all available plugins in certain topics. You can handle all of these management tasks with simple procedures:

Enabling Plugins

Plugins can be enabled and disabled with the configure script. An installed plugin needs to be enabled before it can be used.

Plugin Evaluation Order

By default, TWiki executes plugins in alphabetical order on plugin name. It is possible to change the order, for example to evaluate database variables before the spreadsheet CALCs. This can be done with {PluginsOrder} in the plugins section of configure.

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Plugin-Specific Settings

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Some plugins are configured with plugin preferences variables, newer plugins with configure variables.
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Plugins can be configured with 1. preferences settings and/or 2. with configure settings. Older plugins use plugin preferences settings defined in the plugin topic, which is no longer recommended.
 
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Configure variables are accessible though the configure interface.
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1. Use preferences settings:
 
Changed:
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Plugin preferences variables are defined in the plugin topic and can be overloaded. The SHORTDESCRIPTION preferences variable is always present, it is needed for the TWiki:Plugins repository on twiki.org. Example preferences variable defined in the TablePlugin topic:
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Adinistrators can set plugin-specific settings in the local site preferences at Main.TWikiPreferences and users can overload them at the web level and page level. This approach is recommended if users should be able to overload settings. For security this is not recommended for system settings, such as a path to an executable. By convention, preferences setting names start with the plugin name in all caps, and an underscore. For example, to set the cache refresh period of the TWiki:Plugins.VarCachePlugin, add this bullet in Main.TWikiPreferences
 
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  • Set SHORTDESCRIPTION = Control attributes of tables and sorting of table columns
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  • Set VARCACHEPLUGIN_REFRESH = 24
Deleted:
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Preferences variables of active plugins can be retrieved anywhere in TWiki with %<pluginname>_<var>%, such as %TABLEPLUGIN_SHORTDESCRIPTION%. They can also be redefined with the %<pluginname>_<var>% setting at a lower level in the Main.TWikiPreferences or at the web level. For an easier upgrade it is recommended to customize plugin preferences variables in Main.TWikiPreferences only.
 
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Preferences settings that have been defined in Main.TWikiPreferences can be retrieved anywhere in TWiki with %<pluginname>_<setting>%, such as %VARCACHEPLUGIN_REFRESH%.

To learn how this is done, use the TWiki:Plugins.VarCachePlugin documentation and Perl plugin code as a reference.

2. Use configure settings:

The administrator can set plugin settings in the configure interface. Recommended if only site administrators should be able to change settings. Chose this option to set sensitive or dangerous system settings, such as passwords or path to executables. To define plugin-specific configure settings,

  • Create a Config.spec file in lib/TWiki/Plugins/YourPlugin/ with variables, such as
    $TWiki::cfg{Plugins}{RecentVisitorPlugin}{ShowIP} = 0;
  • In the plugin, use those those variables, such as
    $showIP = $TWiki::cfg{Plugins}{RecentVisitorPlugin}{ShowIP} || 0;

To learn how this is done, use the TWiki:Plugins.RecentVisitorPlugin documentation and Perl plugin code as a reference.

In either case, define a SHORTDESCRIPTION setting in two places:

  • As a setting in the plugin documentation, which is needed for the extension reports on twiki.org. Example:
    • Set SHORTDESCRIPTION = Show recent visitors to a TWiki site
  • As a global Perl package variable in the plugin package, which is needed by TWiki to show info on installed plugins. Example:
    our $SHORTDESCRIPTION = 'Show recent visitors to a TWiki site';

For better performance, make sure you define this in the plugin package:
our $NO_PREFS_IN_TOPIC = 1;

 

Listing Active Plugins

Plugin status variables let you list all active plugins wherever needed.

This site is running TWiki version TWiki-6.1.0, Mon, 16 Jul 2018, build 30610, plugin API version 6.10

%ACTIVATEDPLUGINS%

On this TWiki site, the enabled plugins are: SpreadSheetPlugin, BackupRestorePlugin, ColorPickerPlugin, CommentPlugin, DatePickerPlugin, EditTablePlugin, HeadlinesPlugin, InterwikiPlugin, JQueryPlugin, PreferencesPlugin, SetGetPlugin, SlideShowPlugin, SmiliesPlugin, TWikiSheetPlugin, TablePlugin, TagMePlugin, TinyMCEPlugin, TwistyPlugin, WatchlistPlugin, WysiwygPlugin.

%PLUGINDESCRIPTIONS%

  • SpreadSheetPlugin (2018-07-05, $Rev: 30478 (2018-07-16) $): Add spreadsheet calculation like "$SUM( $ABOVE() )" to TWiki tables or anywhere in topic text
  • BackupRestorePlugin (2021-03-19, $Rev: 30914 (2021-03-19) $): Administrator utility to backup, restore and upgrade a TWiki site
  • ColorPickerPlugin (2018-07-05, $Rev: 30442 (2018-07-16) $): Color picker, packaged for use in TWiki forms and TWiki applications
  • CommentPlugin (2018-07-05, $Rev: 30530 (2018-07-16) $): Quickly post comments to a page without an edit/preview/save cycle
  • DatePickerPlugin (2018-07-05, $Rev: 30446 (2018-07-16) $): Pop-up calendar with date picker, for use in TWiki forms, HTML forms and TWiki plugins
  • EditTablePlugin (2018-07-05, $Rev: 30448 (2018-07-16) $): Edit TWiki tables using edit fields, date pickers and drop down boxes
  • HeadlinesPlugin (2018-07-13, $Rev: 30560 (2018-07-16) $): Show headline news in TWiki pages based on RSS and ATOM news feeds from external sites
  • InterwikiPlugin (2018-07-05, $Rev: 30454 (2018-07-16) $): Write ExternalSite:Page to link to a page on an external site based on aliases defined in a rules topic
  • JQueryPlugin (2018-07-05, $Rev: 30456 (2018-07-16) $): jQuery JavaScript library for TWiki
  • PreferencesPlugin (2018-07-05, $Rev: 30528 (2018-07-16) $): Allows editing of preferences using fields predefined in a form
  • SetGetPlugin (2018-07-05, $Rev: 30472 (2018-07-16) $): Set and get variables and JSON objects in topics, optionally persistently across topic views
  • SlideShowPlugin (2018-07-05, $Rev: 30474 (2018-07-16) $): Create web based presentations based on topics with headings.
  • SmiliesPlugin (2018-07-05, $Rev: 30476 (2018-07-16) $): Render smilies as icons, like  :-) for smile or  :eek: for eek!
  • TWikiSheetPlugin (2018-07-15, $Rev: 30604 (2018-07-16) $): Add TWiki Sheet spreadsheet functionality to TWiki tables
  • TablePlugin (2018-07-05, $Rev: 30480 (2018-07-16) $): Control attributes of tables and sorting of table columns
  • TagMePlugin (2018-07-05, $Rev: 30482 (2018-07-16) $): Tag wiki content collectively or authoritatively to find content by keywords
  • TinyMCEPlugin (2021-06-09, $Rev: 31045 (2021-06-09) $): Integration of the Tiny MCE WYSIWYG Editor
  • TwistyPlugin (2018-07-06, $Rev: 30497 (2018-07-16) $): Twisty section JavaScript library to open/close content dynamically
  • WatchlistPlugin (2018-07-10, $Rev: 30536 (2018-07-16) $): Watch topics of interest and get notified of changes by e-mail
  • WysiwygPlugin (2018-07-06, $Rev: 30528 (2018-07-16) $): Translator framework for WYSIWYG editors

%FAILEDPLUGINS%

PluginErrors
SpreadSheetPlugin none
BackupRestorePlugin none
ColorPickerPlugin none
CommentPlugin none
DatePickerPlugin none
EditTablePlugin none
HeadlinesPlugin none
InterwikiPlugin none
JQueryPlugin none
PreferencesPlugin none
SetGetPlugin none
SlideShowPlugin none
SmiliesPlugin none
TWikiSheetPlugin none
TablePlugin none
TagMePlugin none
TinyMCEPlugin none
TwistyPlugin none
WatchlistPlugin none
WysiwygPlugin none
HandlerPlugins
afterEditHandlerWysiwygPlugin
afterRenameHandlerTagMePlugin
WatchlistPlugin
afterSaveHandlerTagMePlugin
WatchlistPlugin
beforeCommonTagsHandlerEditTablePlugin
PreferencesPlugin
TWikiSheetPlugin
TwistyPlugin
WysiwygPlugin
beforeEditHandlerTinyMCEPlugin
WysiwygPlugin
beforeMergeHandlerWysiwygPlugin
beforeSaveHandlerCommentPlugin
WatchlistPlugin
WysiwygPlugin
commonTagsHandlerSpreadSheetPlugin
BackupRestorePlugin
CommentPlugin
EditTablePlugin
JQueryPlugin
SlideShowPlugin
SmiliesPlugin
TWikiSheetPlugin
initPluginSpreadSheetPlugin
BackupRestorePlugin
ColorPickerPlugin
CommentPlugin
DatePickerPlugin
EditTablePlugin
HeadlinesPlugin
InterwikiPlugin
JQueryPlugin
PreferencesPlugin
SetGetPlugin
SlideShowPlugin
SmiliesPlugin
TWikiSheetPlugin
TablePlugin
TagMePlugin
TinyMCEPlugin
TwistyPlugin
WatchlistPlugin
WysiwygPlugin
modifyHeaderHandlerWysiwygPlugin
postRenderingHandlerPreferencesPlugin
WysiwygPlugin
preRenderingHandlerInterwikiPlugin
SmiliesPlugin
TablePlugin
20 plugins

The TWiki Plugin API

The Application Programming Interface (API) for TWiki plugins provides the specifications for hooking into the core TWiki code from your external Perl plugin module.

Available Core Functions

The TWikiFuncDotPm module (lib/TWiki/Func.pm) describes all the interfaces available to plugins. Plugins should only use the interfaces described in this module.

ALERT! Note: If you use other core functions not described in Func.pm, you run the risk of creating security holes. Also, your plugin will likely break and require updating when you upgrade to a new version of TWiki.

Predefined Hooks

In addition to TWiki core functions, plugins can use predefined hooks, or callbacks, as described in the lib/TWiki/Plugins/EmptyPlugin.pm module.

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  • All but the initPlugin are disabled. To enable a callback, remove DISABLE_ from the function name.
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  • All but the initPlugin are commented out. To enable a callback, remove the leading # from all lines of the callback.
 
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TWiki:Codev/StepByStepRenderingOrder helps you decide which rendering handler to use.
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TWiki:Codev.StepByStepRenderingOrder helps you decide which rendering handler to use.
 

Hints on Writing Fast Plugins

  • Delay initialization as late as possible. For example, if your plugin is a simple syntax processor, you might delay loading extra Perl modules until you actually see the syntax in the text.
    • For example, use an eval block like this:
      eval { require IPC::Run }
      return "<font color=\"red\">SamplePlugin: Can't load required modules ($@)</font>" if $@;
  • Keep the main plugin package as small as possible; create other packages that are loaded if and only if they are used. For example, create sub-packages of BathPlugin in lib/TWiki/Plugins/BathPlugin/.
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  • Avoid using preferences in the plugin topic; set $NO_PREFS_IN_TOPIC if you possibly can, as that will stop TWiki from reading the plugin topic for every page. Use Config.spec instead.
  • Use registered tag handlers
  • Measure the performance to see the difference
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  • Avoid using preferences in the plugin topic; Define $NO_PREFS_IN_TOPIC in your plugin package as that will stop TWiki from reading the plugin topic for every page. Use Config.spec or preferences settings instead. (See details).
  • Use registered tag handlers.
  • Measure the performance to see the difference.
 

Version Detection

To eliminate the incompatibility problems that are bound to arise from active open plugin development, a plugin versioning system is provided for automatic compatibility checking.

  • All plugin packages require a $VERSION variable. This should be an integer, or a subversion version id.

  • The initPlugin handler should check all dependencies and return 1 if the initialization is OK or 0 if something went wrong.
    • The plugin initialization code does not register a plugin that returns 0 (or that has no initPlugin handler).

  • $TWiki::Plugins::VERSION in the TWiki::Plugins module contains the TWiki plugin API version, currently 6.10.
    • You can also use the %PLUGINVERSION{}% variable to query the plugin API version or the version of installed plugins.

Security

  • Badly written plugins can open huge security holes in TWiki. This is especially true if care isn't taken to prevent execution of arbitrary commands on the server.
  • Don't allow sensitive configuration data to be edited by users. it is better to add sensitive configuration options to the %TWiki::cfg hash than adding it as preferences in the plugin topic.
  • Always use the TWiki::Sandbox to execute commands.
  • Always audit the plugins you install, and make sure you are happy with the level of security provided. While every effort is made to monitor plugin authors activities, at the end of the day they are uncontrolled user contributions.

Creating Plugins

With a reasonable knowledge of the Perl scripting language, you can create new plugins or modify and extend existing ones. Basic plug-in architecture uses an Application Programming Interface (API), a set of software instructions that allow external code to interact with the main program. The TWiki Plugin API provides the programming interface for TWiki.

Anatomy of a Plugin

A (very) basic TWiki plugin consists of two files:

  • a Perl module, e.g. MyFirstPlugin.pm
  • a documentation topic, e.g. MyFirstPlugin.txt

The Perl module can be a block of code that talks to with TWiki alone, or it can include other elements, like other Perl modules (including other plugins), graphics, TWiki templates, external applications (ex: a Java applet), or just about anything else it can call. In particular, files that should be web-accessible (graphics, Java applets ...) are best placed as attachments of the MyFirstPlugin topic. Other needed Perl code is best placed in a lib/TWiki/Plugins/MyFirstPlugin/ directory.

The plugin API handles the details of connecting your Perl module with main TWiki code. When you're familiar with the Plugin API, you're ready to develop plugins.

The TWiki:Plugins.BuildContrib module provides a lot of support for plugins development, including a plugin creator, automatic publishing support, and automatic installation script writer. If you plan on writing more than one plugin, you probably need it.

Creating the Perl Module

Copy file lib/TWiki/Plugins/EmptyPlugin.pm to <name>Plugin.pm. The EmptyPlugin.pm module contains mostly empty functions, so it does nothing, but it's ready to be used. Customize it. Refer to the Plugin API specs for more information.

If your plugin uses its own modules and objects, you must include the name of the plugin in the package name. For example, write Package MyFirstPlugin::Attrs; instead of just Package Attrs;. Then call it using:

use TWiki::Plugins::MyFirstPlugin::Attrs;
$var = MyFirstPlugin::Attrs->new();

Writing the Documentation Topic

The plugin documentation topic contains usage instructions and version details. It serves the plugin files as FileAttachments for downloading. (The doc topic is also included in the distribution package.) To create a documentation topic:

  1. Copy the plugin topic template from TWiki.org. To copy the text, go to TWiki:Plugins/PluginPackage and:
    • enter the plugin name in the "How to Create a Plugin" section
    • click Create
    • select all in the Edit box & copy
    • Cancel the edit
    • go back to your site to the TWiki web
    • In the JumpBox enter your plugin name, for example MyFirstPlugin, press enter and create the new topic
    • paste & save new plugin topic on your site
  2. Customize your plugin topic.
    • Important: In case you plan to publish your plugin on TWiki.org, use Interwiki names for author names and links to TWiki.org topics, such as TWiki:Main/TWikiGuest. This is important because links should work properly in a plugin topic installed on any TWiki, not just on TWiki.org.
  3. Document the performance data you gathered while measuring the performance
  4. Save your topic, for use in packaging and publishing your plugin.

OUTLINE: Doc Topic Contents
Check the plugins web on TWiki.org for the latest plugin doc topic template. Here's a quick overview of what's covered:

Syntax Rules: <Describe any special text formatting that will be rendered.>"

Example: <Include an example of the plugin in action. Possibly include a static HTML version of the example to compare if the installation was a success!>"

Plugin Settings: <Description and settings for custom plugin %VARIABLES%, and those required by TWiki.>"

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  • Plugins Preferences <If user settings are needed, explain... Entering values works exactly like TWikiPreferences and WebPreferences: six (6) spaces and then:>"
    • Set <EXAMPLE = value added>
 Plugin Installation Instructions: <Step-by-step set-up guide, user help, whatever it takes to install and run, goes here.>"

Plugin Info: <Version, credits, history, requirements - entered in a form, displayed as a table. Both are automatically generated when you create or edit a page in the TWiki:Plugins web.>"

Packaging for Distribution

The TWiki:Plugins.BuildContrib is a powerful build environment that is used by the TWiki project to build TWiki itself, as well as many of the plugins. You don't have to use it, but it is highly recommended!

If you don't want (or can't) use the BuildContrib, then a minimum plugin release consists of a Perl module with a WikiName that ends in Plugin, ex: MyFirstPlugin.pm, and a documentation page with the same name(MyFirstPlugin.txt).

  1. Distribute the plugin files in a directory structure that mirrors TWiki. If your plugin uses additional files, include them all:
    • lib/TWiki/Plugins/MyFirstPlugin.pm
    • data/TWiki/MyFirstPlugin.txt
    • pub/TWiki/MyFirstPlugin/uparrow.gif [a required graphic]
  2. Create a zip archive with the plugin name (MyFirstPlugin.zip) and add the entire directory structure from Step 1. The archive should look like this:
    • lib/TWiki/Plugins/MyFirstPlugin.pm
    • data/TWiki/MyFirstPlugin.txt
    • pub/TWiki/MyFirstPlugin/uparrow.gif

Measuring and Improving the Plugin Performance

A high quality plugin performs well. You can use the TWiki:Plugins.PluginBenchmarkAddOn to measure your TWiki:Plugins.PluginBenchmarks. The data is needed as part of the Documentation Topic.

See also Hints on Writing Fast Plugins.

Publishing for Public Use

You can release your tested, packaged plugin to the TWiki community through the TWiki:Plugins web. All plugins submitted to TWiki.org are available for download and further development in TWiki:Plugins/PluginPackage.

Publish your plugin by following these steps:

  1. Post the plugin documentation topic in the TWiki:Plugins/PluginPackage:
    • enter the plugin name in the "How to Create a Plugin" section, for example MyFirstPlugin
    • paste in the topic text from Writing the Documentation Topic and save
  2. Attach the distribution zip file to the topic, ex: MyFirstPlugin.zip
  3. Link from the doc page to a new, blank page named after the plugin, and ending in Dev, ex: MyFirstPluginDev. This is the discussion page for future development. (User support for plugins is handled in TWiki:Support.)
  4. Put the plugin into the SVN repository, see TWiki:Plugins/ReadmeFirst (optional)

NEW Once you have done the above steps once, you can use the BuildContrib to upload updates to your plugin.

Thank you very much for sharing your plugin with the TWiki community smile

Recommended Storage of Plugin Specific Data

Plugins sometimes need to store data. This can be plugin internal data such as cache data, or data generated for browser consumption such as images. Plugins should store data using TWikiFuncDotPm functions that support saving and loading of topics and attachments.

Plugin Internal Data

You can create a plugin "work area" using the TWiki::Func::getWorkArea() function, which gives you a persistent directory where you can store data files. By default they will not be web accessible. The directory is guaranteed to exist, and to be writable by the webserver user. For convenience, TWiki::Func::storeFile() and TWiki::Func::readFile() are provided to persistently store and retrieve simple data in this area.

Web Accessible Data

Topic-specific data such as generated images can be stored in the topic's attachment area, which is web accessible. Use the TWiki::Func::saveAttachment() function to store the data.

Recommendation for file name:

  • Prefix the filename with an underscore (the leading underscore avoids a name clash with files attached to the same topic)
  • Identify where the attachment originated from, typically by including the plugin name in the file name
  • Use only alphanumeric characters, underscores, dashes and periods to avoid platform dependency issues and URL issues
  • Example: _GaugePlugin_img123.gif

Web specific data can be stored in the plugin's attachment area, which is web accessible. Use the TWiki::Func::saveAttachment() function to store the data.

Recommendation for file names in plugin attachment area:

  • Prefix the filename with an underscore
  • Include the name of the web in the filename
  • Use only alphanumeric characters, underscores, dashes and periods to avoid platform dependency issues and URL issues
  • Example: _Main_roundedge-ul.gif

Integrating with configure

Some TWiki extensions have setup requirements that are best integrated into configure rather than trying to use TWiki preferences variables. These extensions use Config.spec files to publish their configuration requirements.

Config.spec files are read during TWiki configuration. Once a Config.spec has defined a configuration item, it is available for edit through the standard configure interface. Config.spec files are stored in the 'plugin directory' e.g. lib/TWiki/Plugins/BathPlugin/Config.spec.

Structure of a Config.spec file

The Config.spec file for an extension starts with the extension announcing what it is:
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# ---+ BathPlugin
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# ---+ Extensions
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# ---++ BathPlugin
 # This plugin senses the level of water in your bath, and ensures the plug # is not removed while the water is still warm. This is followed by one or more configuration items. Each configuration item has a type, a description and a default. For example:
# **SELECT Plastic,Rubber,Metal**
# Select the plug type
$TWiki::cfg{BathPlugin}{PlugType} = 'Plastic';

# **NUMBER**
# Enter the chain length in cm
$TWiki::cfg{BathPlugin}{ChainLength} = 30;

# **BOOLEAN EXPERT**
# Set this option to 0 to disable the water temperature alarm
$TWiki::cfg{BathPlugin}{TempSensorEnabled} = 1;
The type (e.g. **SELECT** ) tells configure to how to prompt for the value. It also tells configure how to do some basic checking on the value you actually enter. All the comments between the type and the configuration item are taken as part of the description. The configuration item itself defines the default value for the configuration item. The above spec defines the configuration items $TWiki::cfg{BathPlugin}{PlugType}, $TWiki::cfg{BathPlugin}{ChainLength}, and $TWiki::cfg{BathPlugin}{TempSensorEnabled} for use in your plugin. For example,
if( $TWiki::cfg{BathPlugin}{TempSensorEnabled} && $curTemperature > 50 ) {
    die "The bathwater is too hot for comfort";
}
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The config.spec file is read by configure, which then writes LocalSite.cfg with the values chosen by the local site admin.
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The Config.spec file is read by configure, which then writes LocalSite.cfg with the values chosen by the local site admin.
  A range of types are available for use in Config.spec files:

BOOLEAN A true/false value, represented as a checkbox
COMMAND length A shell command
LANGUAGE A language (selected from {LocalesDir}
NUMBER A number
OCTAL An octal number
PASSWORD length A password (input is hidden)
PATH length A file path
PERL A perl structure, consisting of arrays and hashes
REGEX length A perl regular expression
SELECT choices Pick one of a range of choices
SELECTCLASS root Select a perl package (class)
STRING length A string
URL length A url
URLPATH length A relative URL path

All types can be followed by a comma-separated list of attributes.

EXPERT means this an expert option
M means the setting is mandatory (may not be empty)
H means the option is not visible in configure

See lib/TWiki.spec for many more examples.

Config.spec files for non-plugin extensions are stored under the Contrib directory instead of the Plugins directory.

Note that from TWiki 5.0 onwards, CGI scripts (in the TWiki bin directory) provided by extensions must also have an entry in the Config.spec file. This entry looks like this (example taken from PublishContrib)

# **PERL H**
# Bin script registration - do not modify
$TWiki::cfg{SwitchBoard}{publish} = [ "TWiki::Contrib::Publish", "publish", { publishing => 1 } ];
PERL specifies a perl data structure, and H a hidden setting (it won't appear in configure). The first field of the data value specifies the class where the function that implements the script can be found. The second field specifies the name of the function, which must be the same as the name of the script. The third parameter is a hash of initial context settings for the script.

TWiki:TWiki/SpecifyingConfigurationItemsForExtensions has supplemental documentation on configure settings.

Maintaining Plugins

Discussions and Feedback on Plugins

Each published plugin has a plugin development topic on TWiki.org. Plugin development topics are named after your plugin and end in Dev, such as MyFirstPluginDev. The plugin development topic is a great resource to discuss feature enhancements and to get feedback from the TWiki community.

Maintaining Compatibility with Earlier TWiki Versions

The plugin interface (TWikiFuncDotPm functions and plugin handlers) evolve over time. TWiki introduces new API functions to address the needs of plugin authors. Plugins using unofficial TWiki internal functions may no longer work on a TWiki upgrade.

Organizations typically do not upgrade to the latest TWiki for many months. However, many administrators still would like to install the latest versions of a plugin on their older TWiki installation. This need is fulfilled if plugins are maintained in a compatible manner.

TIP Tip: Plugins can be written to be compatible with older and newer TWiki releases. This can be done also for plugins using unofficial TWiki internal functions of an earlier release that no longer work on the latest TWiki codebase. Here is an example; the TWiki:TWiki.TWikiPluginsSupplement#MaintainPlugins has more details.

    if( $TWiki::Plugins::VERSION >= 1.1 ) {
        @webs = TWiki::Func::getListOfWebs( 'user,public' );
    } else {
        @webs = TWiki::Func::getPublicWebList( );
    }

Handling deprecated functions

From time-to-time, the TWiki developers will add new functions to the interface (either to TWikiFuncDotPm, or new handlers). Sometimes these improvements mean that old functions have to be deprecated to keep the code manageable. When this happens, the deprecated functions will be supported in the interface for at least one more TWiki release, and probably longer, though this cannot be guaranteed.

When a plugin defines deprecated handlers, a warning will be shown in the list generated by %FAILEDPLUGINS%. Admins who see these warnings should check TWiki.org and if necessary, contact the plugin author, for an updated version of the plugin.

Updated plugins may still need to define deprecated handlers for compatibility with old TWiki versions. In this case, the plugin package that defines old handlers can suppress the warnings in %FAILEDPLUGINS%.

This is done by defining a map from the handler name to the TWiki::Plugins version in which the handler was first deprecated. For example, if we need to define the endRenderingHandler for compatibility with TWiki::Plugins versions before 1.1, we would add this to the plugin:

package TWiki::Plugins::SinkPlugin;
use vars qw( %TWikiCompatibility );
$TWikiCompatibility{endRenderingHandler} = 1.1;
If the currently-running TWiki version is 1.1 or later, then the handler will not be called and the warning will not be issued. TWiki with versions of TWiki::Plugins before 1.1 will still call the handler as required.

Related Topics: DeveloperDocumentationCategory, AdminDocumentationCategory, TWiki:TWiki.TWikiPluginsSupplement

-- Contributors: TWiki:Main.PeterThoeny, TWiki:Main.AndreaSterbini, TWiki:Main.MikeMannix, TWiki:Main.CrawfordCurrie, TWiki:Main.ArthurClemens, TWiki:Main.WillNorris

Revision 352010-05-14 - TWikiContributor

 

TWiki Plugins

Add functionality to TWiki with readily available plugins; create plugins based on APIs

Overview

You can add plugins to extend TWiki functionality, without altering the core code. A plug-in approach lets you:

  • add virtually unlimited features while keeping the main TWiki code compact and efficient;
  • heavily customize an installation and still do clean updates to new versions of TWiki;
  • rapidly develop new TWiki functions in Perl using the plugin API.

Everything to do with TWiki plugins - demos, new releases, downloads, development, general discussion - is available at TWiki.org, in the TWiki:Plugins web.

TWiki plugins are developed and contributed by interested members of the community. Plugins are provided on an 'as is' basis; they are not a part of TWiki, but are independently developed and maintained.

Relevant links on TWiki.org:

See other types of extensions: TWikiAddOns, TWikiContribs, TWikiSkins

Installing Plugins

Each TWiki plugin comes with its own documentation: step-by-step installation instructions, a detailed description of any special requirements, version details, and a working example for testing. Many plugins have an install script that automates these steps for you.

Special Requirements: Some plugins need certain Perl modules to be preinstalled on the host system. Plugins may also use other resources, like graphics, other modules, applications, and templates. You should be able to find detailed instructions in the plugin's documentation.

Each plugin has a standard release topic, located in the TWiki:Plugins web at TWiki.org. There's usually a number of other related topics, such as a developers page, and an appraisal page.

On-Site Pretesting

The recommended approach to testing new plugins before making them public is to create a second local TWiki installation, and test the plugin there. You can allow selected users access to the test area. Once you are satisfied that it won't compromise your main installation, you can install it there as well.

InstalledPlugins shows which plugins are: 1) installed, 2) loading properly, and 3) what TWiki:Codev.PluginHandlers they invoke. Any failures are shown in the Errors section. The %FAILEDPLUGINS% variable can be used to debug failures. You may also want to check your webserver error log and the various TWiki log files.

Some Notes on Plugin Performance

The performance of the system depends to some extent on the number of plugins installed and on the plugin implementation. Some plugins impose no measurable performance decrease, some do. For example, a Plugin might use many Perl libraries that need to be initialized with each page view (unless you run mod_perl). You can only really tell the performance impact by installing the plugin and by measuring the performance with and without the new plugin. Use the TWiki:Plugins.PluginBenchmarkAddOn, or test manually with the Apache ab utility. Example on Unix:
time wget -qO /dev/null /twiki/bin/view/TWiki/AbcPlugin

TIP If you need to install an "expensive" plugin, but you only need its functionality only in a subset of your data, you can disable it elsewhere by defining the %DISABLEDPLUGINS% TWiki variable.

Define DISABLEDPLUGINS to be a comma-separated list of names of plugins to disable. Define it in Main.TWikiPreferences to disable those plugins everywhere, in the WebPreferences topic to disable them in an individual web, or in a topic to disable them in that topic. For example,

   * Set DISABLEDPLUGINS = SpreadSheetPlugin, EditTablePlugin

Managing Installed Plugins

Some plugins require additional settings or offer extra options that you have to select. Also, you may want to make a plugin available only in certain webs, or temporarily disable it. And may want to list all available plugins in certain topics. You can handle all of these management tasks with simple procedures:

Enabling Plugins

Plugins can be enabled and disabled with the configure script. An installed plugin needs to be enabled before it can be used.

Plugin Evaluation Order

By default, TWiki executes plugins in alphabetical order on plugin name. It is possible to change the order, for example to evaluate database variables before the spreadsheet CALCs. This can be done with {PluginsOrder} in the plugins section of configure.

Plugin-Specific Settings

Some plugins are configured with plugin preferences variables, newer plugins with configure variables.

Configure variables are accessible though the configure interface.

Plugin preferences variables are defined in the plugin topic and can be overloaded. The SHORTDESCRIPTION preferences variable is always present, it is needed for the TWiki:Plugins repository on twiki.org. Example preferences variable defined in the TablePlugin topic:

  • Set SHORTDESCRIPTION = Control attributes of tables and sorting of table columns

Preferences variables of active plugins can be retrieved anywhere in TWiki with %<pluginname>_<var>%, such as %TABLEPLUGIN_SHORTDESCRIPTION%. They can also be redefined with the %<pluginname>_<var>% setting at a lower level in the Main.TWikiPreferences or at the web level. For an easier upgrade it is recommended to customize plugin preferences variables in Main.TWikiPreferences only.

Listing Active Plugins

Plugin status variables let you list all active plugins wherever needed.

This site is running TWiki version TWiki-6.1.0, Mon, 16 Jul 2018, build 30610, plugin API version 6.10

%ACTIVATEDPLUGINS%

On this TWiki site, the enabled plugins are: SpreadSheetPlugin, BackupRestorePlugin, ColorPickerPlugin, CommentPlugin, DatePickerPlugin, EditTablePlugin, HeadlinesPlugin, InterwikiPlugin, JQueryPlugin, PreferencesPlugin, SetGetPlugin, SlideShowPlugin, SmiliesPlugin, TWikiSheetPlugin, TablePlugin, TagMePlugin, TinyMCEPlugin, TwistyPlugin, WatchlistPlugin, WysiwygPlugin.

%PLUGINDESCRIPTIONS%

  • SpreadSheetPlugin (2018-07-05, $Rev: 30478 (2018-07-16) $): Add spreadsheet calculation like "$SUM( $ABOVE() )" to TWiki tables or anywhere in topic text
  • BackupRestorePlugin (2021-03-19, $Rev: 30914 (2021-03-19) $): Administrator utility to backup, restore and upgrade a TWiki site
  • ColorPickerPlugin (2018-07-05, $Rev: 30442 (2018-07-16) $): Color picker, packaged for use in TWiki forms and TWiki applications
  • CommentPlugin (2018-07-05, $Rev: 30530 (2018-07-16) $): Quickly post comments to a page without an edit/preview/save cycle
  • DatePickerPlugin (2018-07-05, $Rev: 30446 (2018-07-16) $): Pop-up calendar with date picker, for use in TWiki forms, HTML forms and TWiki plugins
  • EditTablePlugin (2018-07-05, $Rev: 30448 (2018-07-16) $): Edit TWiki tables using edit fields, date pickers and drop down boxes
  • HeadlinesPlugin (2018-07-13, $Rev: 30560 (2018-07-16) $): Show headline news in TWiki pages based on RSS and ATOM news feeds from external sites
  • InterwikiPlugin (2018-07-05, $Rev: 30454 (2018-07-16) $): Write ExternalSite:Page to link to a page on an external site based on aliases defined in a rules topic
  • JQueryPlugin (2018-07-05, $Rev: 30456 (2018-07-16) $): jQuery JavaScript library for TWiki
  • PreferencesPlugin (2018-07-05, $Rev: 30528 (2018-07-16) $): Allows editing of preferences using fields predefined in a form
  • SetGetPlugin (2018-07-05, $Rev: 30472 (2018-07-16) $): Set and get variables and JSON objects in topics, optionally persistently across topic views
  • SlideShowPlugin (2018-07-05, $Rev: 30474 (2018-07-16) $): Create web based presentations based on topics with headings.
  • SmiliesPlugin (2018-07-05, $Rev: 30476 (2018-07-16) $): Render smilies as icons, like  :-) for smile or  :eek: for eek!
  • TWikiSheetPlugin (2018-07-15, $Rev: 30604 (2018-07-16) $): Add TWiki Sheet spreadsheet functionality to TWiki tables
  • TablePlugin (2018-07-05, $Rev: 30480 (2018-07-16) $): Control attributes of tables and sorting of table columns
  • TagMePlugin (2018-07-05, $Rev: 30482 (2018-07-16) $): Tag wiki content collectively or authoritatively to find content by keywords
  • TinyMCEPlugin (2021-06-09, $Rev: 31045 (2021-06-09) $): Integration of the Tiny MCE WYSIWYG Editor
  • TwistyPlugin (2018-07-06, $Rev: 30497 (2018-07-16) $): Twisty section JavaScript library to open/close content dynamically
  • WatchlistPlugin (2018-07-10, $Rev: 30536 (2018-07-16) $): Watch topics of interest and get notified of changes by e-mail
  • WysiwygPlugin (2018-07-06, $Rev: 30528 (2018-07-16) $): Translator framework for WYSIWYG editors

%FAILEDPLUGINS%

PluginErrors
SpreadSheetPlugin none
BackupRestorePlugin none
ColorPickerPlugin none
CommentPlugin none
DatePickerPlugin none
EditTablePlugin none
HeadlinesPlugin none
InterwikiPlugin none
JQueryPlugin none
PreferencesPlugin none
SetGetPlugin none
SlideShowPlugin none
SmiliesPlugin none
TWikiSheetPlugin none
TablePlugin none
TagMePlugin none
TinyMCEPlugin none
TwistyPlugin none
WatchlistPlugin none
WysiwygPlugin none
HandlerPlugins
afterEditHandlerWysiwygPlugin
afterRenameHandlerTagMePlugin
WatchlistPlugin
afterSaveHandlerTagMePlugin
WatchlistPlugin
beforeCommonTagsHandlerEditTablePlugin
PreferencesPlugin
TWikiSheetPlugin
TwistyPlugin
WysiwygPlugin
beforeEditHandlerTinyMCEPlugin
WysiwygPlugin
beforeMergeHandlerWysiwygPlugin
beforeSaveHandlerCommentPlugin
WatchlistPlugin
WysiwygPlugin
commonTagsHandlerSpreadSheetPlugin
BackupRestorePlugin
CommentPlugin
EditTablePlugin
JQueryPlugin
SlideShowPlugin
SmiliesPlugin
TWikiSheetPlugin
initPluginSpreadSheetPlugin
BackupRestorePlugin
ColorPickerPlugin
CommentPlugin
DatePickerPlugin
EditTablePlugin
HeadlinesPlugin
InterwikiPlugin
JQueryPlugin
PreferencesPlugin
SetGetPlugin
SlideShowPlugin
SmiliesPlugin
TWikiSheetPlugin
TablePlugin
TagMePlugin
TinyMCEPlugin
TwistyPlugin
WatchlistPlugin
WysiwygPlugin
modifyHeaderHandlerWysiwygPlugin
postRenderingHandlerPreferencesPlugin
WysiwygPlugin
preRenderingHandlerInterwikiPlugin
SmiliesPlugin
TablePlugin
20 plugins

The TWiki Plugin API

The Application Programming Interface (API) for TWiki plugins provides the specifications for hooking into the core TWiki code from your external Perl plugin module.

Available Core Functions

The TWikiFuncDotPm module (lib/TWiki/Func.pm) describes all the interfaces available to plugins. Plugins should only use the interfaces described in this module.

ALERT! Note: If you use other core functions not described in Func.pm, you run the risk of creating security holes. Also, your plugin will likely break and require updating when you upgrade to a new version of TWiki.

Predefined Hooks

In addition to TWiki core functions, plugins can use predefined hooks, or callbacks, as described in the lib/TWiki/Plugins/EmptyPlugin.pm module.

  • All but the initPlugin are disabled. To enable a callback, remove DISABLE_ from the function name.

TWiki:Codev/StepByStepRenderingOrder helps you decide which rendering handler to use.

Hints on Writing Fast Plugins

  • Delay initialization as late as possible. For example, if your plugin is a simple syntax processor, you might delay loading extra Perl modules until you actually see the syntax in the text.
    • For example, use an eval block like this:
      eval { require IPC::Run }
      return "<font color=\"red\">SamplePlugin: Can't load required modules ($@)</font>" if $@;
  • Keep the main plugin package as small as possible; create other packages that are loaded if and only if they are used. For example, create sub-packages of BathPlugin in lib/TWiki/Plugins/BathPlugin/.
  • Avoid using preferences in the plugin topic; set $NO_PREFS_IN_TOPIC if you possibly can, as that will stop TWiki from reading the plugin topic for every page. Use Config.spec instead.
  • Use registered tag handlers
  • Measure the performance to see the difference

Version Detection

To eliminate the incompatibility problems that are bound to arise from active open plugin development, a plugin versioning system is provided for automatic compatibility checking.

  • All plugin packages require a $VERSION variable. This should be an integer, or a subversion version id.

  • The initPlugin handler should check all dependencies and return 1 if the initialization is OK or 0 if something went wrong.
    • The plugin initialization code does not register a plugin that returns 0 (or that has no initPlugin handler).

  • $TWiki::Plugins::VERSION in the TWiki::Plugins module contains the TWiki plugin API version, currently 6.10.
    • You can also use the %PLUGINVERSION{}% variable to query the plugin API version or the version of installed plugins.

Security

  • Badly written plugins can open huge security holes in TWiki. This is especially true if care isn't taken to prevent execution of arbitrary commands on the server.
  • Don't allow sensitive configuration data to be edited by users. it is better to add sensitive configuration options to the %TWiki::cfg hash than adding it as preferences in the plugin topic.
  • Always use the TWiki::Sandbox to execute commands.
  • Always audit the plugins you install, and make sure you are happy with the level of security provided. While every effort is made to monitor plugin authors activities, at the end of the day they are uncontrolled user contributions.

Creating Plugins

With a reasonable knowledge of the Perl scripting language, you can create new plugins or modify and extend existing ones. Basic plug-in architecture uses an Application Programming Interface (API), a set of software instructions that allow external code to interact with the main program. The TWiki Plugin API provides the programming interface for TWiki.

Anatomy of a Plugin

A (very) basic TWiki plugin consists of two files:

  • a Perl module, e.g. MyFirstPlugin.pm
  • a documentation topic, e.g. MyFirstPlugin.txt

The Perl module can be a block of code that talks to with TWiki alone, or it can include other elements, like other Perl modules (including other plugins), graphics, TWiki templates, external applications (ex: a Java applet), or just about anything else it can call. In particular, files that should be web-accessible (graphics, Java applets ...) are best placed as attachments of the MyFirstPlugin topic. Other needed Perl code is best placed in a lib/TWiki/Plugins/MyFirstPlugin/ directory.

The plugin API handles the details of connecting your Perl module with main TWiki code. When you're familiar with the Plugin API, you're ready to develop plugins.

The TWiki:Plugins.BuildContrib module provides a lot of support for plugins development, including a plugin creator, automatic publishing support, and automatic installation script writer. If you plan on writing more than one plugin, you probably need it.

Creating the Perl Module

Copy file lib/TWiki/Plugins/EmptyPlugin.pm to <name>Plugin.pm. The EmptyPlugin.pm module contains mostly empty functions, so it does nothing, but it's ready to be used. Customize it. Refer to the Plugin API specs for more information.

If your plugin uses its own modules and objects, you must include the name of the plugin in the package name. For example, write Package MyFirstPlugin::Attrs; instead of just Package Attrs;. Then call it using:

use TWiki::Plugins::MyFirstPlugin::Attrs;
$var = MyFirstPlugin::Attrs->new();

Writing the Documentation Topic

The plugin documentation topic contains usage instructions and version details. It serves the plugin files as FileAttachments for downloading. (The doc topic is also included in the distribution package.) To create a documentation topic:

  1. Copy the plugin topic template from TWiki.org. To copy the text, go to TWiki:Plugins/PluginPackage and:
    • enter the plugin name in the "How to Create a Plugin" section
    • click Create
    • select all in the Edit box & copy
    • Cancel the edit
    • go back to your site to the TWiki web
Changed:
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    • In the GoBox enter your plugin name, for example MyFirstPlugin, press enter and create the new topic
>
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    • In the JumpBox enter your plugin name, for example MyFirstPlugin, press enter and create the new topic
 
    • paste & save new plugin topic on your site
  1. Customize your plugin topic.
    • Important: In case you plan to publish your plugin on TWiki.org, use Interwiki names for author names and links to TWiki.org topics, such as TWiki:Main/TWikiGuest. This is important because links should work properly in a plugin topic installed on any TWiki, not just on TWiki.org.
  2. Document the performance data you gathered while measuring the performance
  3. Save your topic, for use in packaging and publishing your plugin.

OUTLINE: Doc Topic Contents
Check the plugins web on TWiki.org for the latest plugin doc topic template. Here's a quick overview of what's covered:

Syntax Rules: <Describe any special text formatting that will be rendered.>"

Example: <Include an example of the plugin in action. Possibly include a static HTML version of the example to compare if the installation was a success!>"

Plugin Settings: <Description and settings for custom plugin %VARIABLES%, and those required by TWiki.>"

  • Plugins Preferences <If user settings are needed, explain... Entering values works exactly like TWikiPreferences and WebPreferences: six (6) spaces and then:>"
    • Set <EXAMPLE = value added>

Plugin Installation Instructions: <Step-by-step set-up guide, user help, whatever it takes to install and run, goes here.>"

Plugin Info: <Version, credits, history, requirements - entered in a form, displayed as a table. Both are automatically generated when you create or edit a page in the TWiki:Plugins web.>"

Packaging for Distribution

The TWiki:Plugins.BuildContrib is a powerful build environment that is used by the TWiki project to build TWiki itself, as well as many of the plugins. You don't have to use it, but it is highly recommended!

If you don't want (or can't) use the BuildContrib, then a minimum plugin release consists of a Perl module with a WikiName that ends in Plugin, ex: MyFirstPlugin.pm, and a documentation page with the same name(MyFirstPlugin.txt).

  1. Distribute the plugin files in a directory structure that mirrors TWiki. If your plugin uses additional files, include them all:
    • lib/TWiki/Plugins/MyFirstPlugin.pm
    • data/TWiki/MyFirstPlugin.txt
    • pub/TWiki/MyFirstPlugin/uparrow.gif [a required graphic]
  2. Create a zip archive with the plugin name (MyFirstPlugin.zip) and add the entire directory structure from Step 1. The archive should look like this:
    • lib/TWiki/Plugins/MyFirstPlugin.pm
    • data/TWiki/MyFirstPlugin.txt
    • pub/TWiki/MyFirstPlugin/uparrow.gif

Measuring and Improving the Plugin Performance

A high quality plugin performs well. You can use the TWiki:Plugins.PluginBenchmarkAddOn to measure your TWiki:Plugins.PluginBenchmarks. The data is needed as part of the Documentation Topic.

See also Hints on Writing Fast Plugins.

Publishing for Public Use

You can release your tested, packaged plugin to the TWiki community through the TWiki:Plugins web. All plugins submitted to TWiki.org are available for download and further development in TWiki:Plugins/PluginPackage.

Publish your plugin by following these steps:

  1. Post the plugin documentation topic in the TWiki:Plugins/PluginPackage:
    • enter the plugin name in the "How to Create a Plugin" section, for example MyFirstPlugin
    • paste in the topic text from Writing the Documentation Topic and save
  2. Attach the distribution zip file to the topic, ex: MyFirstPlugin.zip
  3. Link from the doc page to a new, blank page named after the plugin, and ending in Dev, ex: MyFirstPluginDev. This is the discussion page for future development. (User support for plugins is handled in TWiki:Support.)
  4. Put the plugin into the SVN repository, see TWiki:Plugins/ReadmeFirst (optional)

NEW Once you have done the above steps once, you can use the BuildContrib to upload updates to your plugin.

Thank you very much for sharing your plugin with the TWiki community smile

Recommended Storage of Plugin Specific Data

Plugins sometimes need to store data. This can be plugin internal data such as cache data, or data generated for browser consumption such as images. Plugins should store data using TWikiFuncDotPm functions that support saving and loading of topics and attachments.

Plugin Internal Data

You can create a plugin "work area" using the TWiki::Func::getWorkArea() function, which gives you a persistent directory where you can store data files. By default they will not be web accessible. The directory is guaranteed to exist, and to be writable by the webserver user. For convenience, TWiki::Func::storeFile() and TWiki::Func::readFile() are provided to persistently store and retrieve simple data in this area.

Web Accessible Data

Topic-specific data such as generated images can be stored in the topic's attachment area, which is web accessible. Use the TWiki::Func::saveAttachment() function to store the data.

Recommendation for file name:

  • Prefix the filename with an underscore (the leading underscore avoids a name clash with files attached to the same topic)
  • Identify where the attachment originated from, typically by including the plugin name in the file name
  • Use only alphanumeric characters, underscores, dashes and periods to avoid platform dependency issues and URL issues
  • Example: _GaugePlugin_img123.gif

Web specific data can be stored in the plugin's attachment area, which is web accessible. Use the TWiki::Func::saveAttachment() function to store the data.

Recommendation for file names in plugin attachment area:

  • Prefix the filename with an underscore
  • Include the name of the web in the filename
  • Use only alphanumeric characters, underscores, dashes and periods to avoid platform dependency issues and URL issues
  • Example: _Main_roundedge-ul.gif

Integrating with configure

Some TWiki extensions have setup requirements that are best integrated into configure rather than trying to use TWiki preferences variables. These extensions use Config.spec files to publish their configuration requirements.

Config.spec files are read during TWiki configuration. Once a Config.spec has defined a configuration item, it is available for edit through the standard configure interface. Config.spec files are stored in the 'plugin directory' e.g. lib/TWiki/Plugins/BathPlugin/Config.spec.

Structure of a Config.spec file

Changed:
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The Config.spec file for a plugin starts with the plugin announcing what it is:
>
>
The Config.spec file for an extension starts with the extension announcing what it is:
 
# ---+ BathPlugin
# This plugin senses the level of water in your bath, and ensures the plug
# is not removed while the water is still warm.
This is followed by one or more configuration items. Each configuration item has a type, a description and a default. For example:
# **SELECT Plastic,Rubber,Metal**
# Select the plug type
$TWiki::cfg{BathPlugin}{PlugType} = 'Plastic';

# **NUMBER**
# Enter the chain length in cm
Changed:
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$TWiki::cfg{BathPlugin}{ChainLength} = '30';
>
>
$TWiki::cfg{BathPlugin}{ChainLength} = 30;
  # *BOOLEAN EXPERT*
Changed:
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<
# Turn this option off to disable the water temperature alarm $TWiki::cfg{BathPlugin}{TempSensorEnabled} = '1';
>
>
# Set this option to 0 to disable the water temperature alarm $TWiki::cfg{BathPlugin}{TempSensorEnabled} = 1;
 
Changed:
<
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The type (e.g. **SELECT** ) tells configure to how to prompt for the value. It also tells configure how to do some basic checking on the value you actually enter. All the comments between the type and the configuration item are taken as part of the description. The configuration item itself defines the default value for the configuration item. The above spec defines the configuration items $TWiki::cfg{BathPlugin}{PlugType}, $TWiki::cfg{BathPlugin}{ChainLength}, and $TWiki::cfg{BathPlugin}{TempSensorEnabled} for use in your plugin. For example,
>
>
The type (e.g. **SELECT** ) tells configure to how to prompt for the value. It also tells configure how to do some basic checking on the value you actually enter. All the comments between the type and the configuration item are taken as part of the description. The configuration item itself defines the default value for the configuration item. The above spec defines the configuration items $TWiki::cfg{BathPlugin}{PlugType}, $TWiki::cfg{BathPlugin}{ChainLength}, and $TWiki::cfg{BathPlugin}{TempSensorEnabled} for use in your plugin. For example,
 
if( $TWiki::cfg{BathPlugin}{TempSensorEnabled} && $curTemperature > 50 ) {
    die "The bathwater is too hot for comfort";
}
Changed:
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The config.spec file is read by configure, and configure then writes LocalSite.cfg with the values chosen by the local site admin.
>
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The config.spec file is read by configure, which then writes LocalSite.cfg with the values chosen by the local site admin.
  A range of types are available for use in Config.spec files:

BOOLEAN A true/false value, represented as a checkbox
COMMAND length A shell command
LANGUAGE A language (selected from {LocalesDir}
NUMBER A number
OCTAL An octal number
PASSWORD length A password (input is hidden)
PATH length A file path
PERL A perl structure, consisting of arrays and hashes
REGEX length A perl regular expression
SELECT choices Pick one of a range of choices
SELECTCLASS root Select a perl package (class)
STRING length A string
URL length A url
URLPATH length A relative URL path

All types can be followed by a comma-separated list of attributes.

EXPERT means this an expert option
M means the setting is mandatory (may not be empty)
H means the option is not visible in configure

See lib/TWiki.spec for many more examples.

Changed:
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Config.spec files are also used for other (non-plugin) extensions. in this case they are stored under the Contrib directory instead of the Plugins directory.
>
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Config.spec files for non-plugin extensions are stored under the Contrib directory instead of the Plugins directory.
 
Added:
>
>
Note that from TWiki 5.0 onwards, CGI scripts (in the TWiki bin directory) provided by extensions must also have an entry in the Config.spec file. This entry looks like this (example taken from PublishContrib)

# **PERL H**
# Bin script registration - do not modify
$TWiki::cfg{SwitchBoard}{publish} = [ "TWiki::Contrib::Publish", "publish", { publishing => 1 } ];
PERL specifies a perl data structure, and H a hidden setting (it won't appear in configure). The first field of the data value specifies the class where the function that implements the script can be found. The second field specifies the name of the function, which must be the same as the name of the script. The third parameter is a hash of initial context settings for the script.
 TWiki:TWiki/SpecifyingConfigurationItemsForExtensions has supplemental documentation on configure settings.

Maintaining Plugins

Discussions and Feedback on Plugins

Each published plugin has a plugin development topic on TWiki.org. Plugin development topics are named after your plugin and end in Dev, such as MyFirstPluginDev. The plugin development topic is a great resource to discuss feature enhancements and to get feedback from the TWiki community.

Maintaining Compatibility with Earlier TWiki Versions

The plugin interface (TWikiFuncDotPm functions and plugin handlers) evolve over time. TWiki introduces new API functions to address the needs of plugin authors. Plugins using unofficial TWiki internal functions may no longer work on a TWiki upgrade.

Organizations typically do not upgrade to the latest TWiki for many months. However, many administrators still would like to install the latest versions of a plugin on their older TWiki installation. This need is fulfilled if plugins are maintained in a compatible manner.

TIP Tip: Plugins can be written to be compatible with older and newer TWiki releases. This can be done also for plugins using unofficial TWiki internal functions of an earlier release that no longer work on the latest TWiki codebase. Here is an example; the TWiki:TWiki.TWikiPluginsSupplement#MaintainPlugins has more details.

    if( $TWiki::Plugins::VERSION >= 1.1 ) {
        @webs = TWiki::Func::getListOfWebs( 'user,public' );
    } else {
        @webs = TWiki::Func::getPublicWebList( );
    }

Handling deprecated functions

From time-to-time, the TWiki developers will add new functions to the interface (either to TWikiFuncDotPm, or new handlers). Sometimes these improvements mean that old functions have to be deprecated to keep the code manageable. When this happens, the deprecated functions will be supported in the interface for at least one more TWiki release, and probably longer, though this cannot be guaranteed.

When a plugin defines deprecated handlers, a warning will be shown in the list generated by %FAILEDPLUGINS%. Admins who see these warnings should check TWiki.org and if necessary, contact the plugin author, for an updated version of the plugin.

Updated plugins may still need to define deprecated handlers for compatibility with old TWiki versions. In this case, the plugin package that defines old handlers can suppress the warnings in %FAILEDPLUGINS%.

This is done by defining a map from the handler name to the TWiki::Plugins version in which the handler was first deprecated. For example, if we need to define the endRenderingHandler for compatibility with TWiki::Plugins versions before 1.1, we would add this to the plugin:

package TWiki::Plugins::SinkPlugin;
use vars qw( %TWikiCompatibility );
$TWikiCompatibility{endRenderingHandler} = 1.1;
If the currently-running TWiki version is 1.1 or later, then the handler will not be called and the warning will not be issued. TWiki with versions of TWiki::Plugins before 1.1 will still call the handler as required.

Related Topics: DeveloperDocumentationCategory, AdminDocumentationCategory, TWiki:TWiki.TWikiPluginsSupplement

-- Contributors: TWiki:Main.PeterThoeny, TWiki:Main.AndreaSterbini, TWiki:Main.MikeMannix, TWiki:Main.CrawfordCurrie, TWiki:Main.ArthurClemens, TWiki:Main.WillNorris

Deleted:
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Revision 342008-04-19 - TWikiContributor

 

TWiki Plugins

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Add functionality to TWiki with readily available Plugins; create Plugins based on APIs
>
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Add functionality to TWiki with readily available plugins; create plugins based on APIs
 

Overview

Changed:
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You can add Plugins to extend TWiki functionality, without altering the core code. A plug-in approach lets you:
>
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You can add plugins to extend TWiki functionality, without altering the core code. A plug-in approach lets you:
 
  • add virtually unlimited features while keeping the main TWiki code compact and efficient;
  • heavily customize an installation and still do clean updates to new versions of TWiki;
Changed:
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  • rapidly develop new TWiki functions in Perl using the Plugin API.
>
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  • rapidly develop new TWiki functions in Perl using the plugin API.
 
Changed:
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Everything to do with TWiki Plugins - demos, new releases, downloads, development, general discussion - is available at TWiki.org, in the TWiki:Plugins web.
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Everything to do with TWiki plugins - demos, new releases, downloads, development, general discussion - is available at TWiki.org, in the TWiki:Plugins web.
 
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TWiki Plugins are developed and contributed by interested members of the community. Plugins are provided on an 'as is' basis; they are not a part of TWiki, but are independently developed and maintained.
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TWiki plugins are developed and contributed by interested members of the community. Plugins are provided on an 'as is' basis; they are not a part of TWiki, but are independently developed and maintained.
  Relevant links on TWiki.org:

See other types of extensions: TWikiAddOns, TWikiContribs, TWikiSkins

Installing Plugins

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Each TWiki Plugin comes with its own documentation: step-by-step installation instructions, a detailed description of any special requirements, version details, and a working example for testing. Many Plugins have an install script that automates these steps for you.
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Each TWiki plugin comes with its own documentation: step-by-step installation instructions, a detailed description of any special requirements, version details, and a working example for testing. Many plugins have an install script that automates these steps for you.
 
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Special Requirements: Some Plugins need certain Perl modules to be preinstalled on the host system. Plugins may also use other resources, like graphics, other modules, applications, and templates. You should be able to find detailed instructions in the Plugin's documentation.
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Special Requirements: Some plugins need certain Perl modules to be preinstalled on the host system. Plugins may also use other resources, like graphics, other modules, applications, and templates. You should be able to find detailed instructions in the plugin's documentation.
 
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Each Plugin has a standard release topic, located in the TWiki:Plugins web at TWiki.org. There's usually a number of other related topics, such as a developers page, and an appraisal page.
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Each plugin has a standard release topic, located in the TWiki:Plugins web at TWiki.org. There's usually a number of other related topics, such as a developers page, and an appraisal page.
 

On-Site Pretesting

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The recommended approach to testing new Plugins before making them public is to create a second local TWiki installation, and test the Plugin there. You can allow selected users access to the test area. Once you are satisfied that it won't compromise your main installation, you can install it there as well.
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The recommended approach to testing new plugins before making them public is to create a second local TWiki installation, and test the plugin there. You can allow selected users access to the test area. Once you are satisfied that it won't compromise your main installation, you can install it there as well.
 
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InstalledPlugins shows which Plugins are: 1) installed, 2) loading properly, and 3) what TWiki:Codev.PluginHandlers they invoke. Any failures are shown in the Errors section. The %FAILEDPLUGINS% variable can be used to debug failures. You may also want to check your webserver error log and the various TWiki log files.
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InstalledPlugins shows which plugins are: 1) installed, 2) loading properly, and 3) what TWiki:Codev.PluginHandlers they invoke. Any failures are shown in the Errors section. The %FAILEDPLUGINS% variable can be used to debug failures. You may also want to check your webserver error log and the various TWiki log files.
 

Some Notes on Plugin Performance

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The performance of the system depends to some extent on the number of Plugins installed and on the Plugin implementation. Some Plugins impose no measurable performance decrease, some do. For example, a Plugin might use many Perl libraries that need to be initialized with each page view (unless you run mod_perl). You can only really tell the performance impact by installing the Plugin and by measuring the performance with and without the new Plugin. Use the TWiki:Plugins.PluginBenchmarkAddOn, or test manually with the Apache ab utility. Example on Unix:
time wget -qO /dev/null /twiki/bin/view/TWiki/AbcPlugin
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The performance of the system depends to some extent on the number of plugins installed and on the plugin implementation. Some plugins impose no measurable performance decrease, some do. For example, a Plugin might use many Perl libraries that need to be initialized with each page view (unless you run mod_perl). You can only really tell the performance impact by installing the plugin and by measuring the performance with and without the new plugin. Use the TWiki:Plugins.PluginBenchmarkAddOn, or test manually with the Apache ab utility. Example on Unix:
time wget -qO /dev/null /twiki/bin/view/TWiki/AbcPlugin
 
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TIP If you need to install an "expensive" Plugin, but you only need its functionality only in a subset of your data, you can disable it elsewhere by defining the %DISABLEDPLUGINS% TWiki variable.
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TIP If you need to install an "expensive" plugin, but you only need its functionality only in a subset of your data, you can disable it elsewhere by defining the %DISABLEDPLUGINS% TWiki variable.
  Define DISABLEDPLUGINS to be a comma-separated list of names of plugins to disable. Define it in Main.TWikiPreferences to disable those plugins everywhere, in the WebPreferences topic to disable them in an individual web, or in a topic to disable them in that topic. For example,
   * Set DISABLEDPLUGINS = SpreadSheetPlugin, EditTablePlugin

Managing Installed Plugins

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Some Plugins require additional settings or offer extra options that you have to select. Also, you may want to make a Plugin available only in certain webs, or temporarily disable it. And may want to list all available Plugins in certain topics. You can handle all of these management tasks with simple procedures:
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Some plugins require additional settings or offer extra options that you have to select. Also, you may want to make a plugin available only in certain webs, or temporarily disable it. And may want to list all available plugins in certain topics. You can handle all of these management tasks with simple procedures:
 

Enabling Plugins

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Plugins can be enabled and disabled with the configure script. An installed Plugin needs to be enabled before it can be used.
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Plugins can be enabled and disabled with the configure script. An installed plugin needs to be enabled before it can be used.
 

Plugin Evaluation Order

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By default, TWiki executes Plugins in alphabetical order on Plugin name. It is possible to change the order, for example to evaluate database variables before the spreadsheet CALCs. This can be done with {PluginsOrder} in the Plugins section of configure.
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By default, TWiki executes plugins in alphabetical order on plugin name. It is possible to change the order, for example to evaluate database variables before the spreadsheet CALCs. This can be done with {PluginsOrder} in the plugins section of configure.
 

Plugin-Specific Settings

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Plugins are usually configured by variables accessible though the configure interface, but in some cases (usually older plugins) TWiki preferences are used. If a TWiki variable is defined in a Plugin topic e.g:
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Some plugins are configured with plugin preferences variables, newer plugins with configure variables.
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  • Set SETTING = Create dynamic foo bar reports
Then these settings can be retrieved as preferences variables like %<pluginname>_<var>%. For example, %RUBBERPLUGIN_SETTING% shows the value of SETTING in the RubberPlugin topic.
 
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Configure variables are accessible though the configure interface.

Plugin preferences variables are defined in the plugin topic and can be overloaded. The SHORTDESCRIPTION preferences variable is always present, it is needed for the TWiki:Plugins repository on twiki.org. Example preferences variable defined in the TablePlugin topic:

  • Set SHORTDESCRIPTION = Control attributes of tables and sorting of table columns

Preferences variables of active plugins can be retrieved anywhere in TWiki with %<pluginname>_<var>%, such as %TABLEPLUGIN_SHORTDESCRIPTION%. They can also be redefined with the %<pluginname>_<var>% setting at a lower level in the Main.TWikiPreferences or at the web level. For an easier upgrade it is recommended to customize plugin preferences variables in Main.TWikiPreferences only.

 

Listing Active Plugins

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Plugin status variables let you list all active Plugins wherever needed.
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Plugin status variables let you list all active plugins wherever needed.
 
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This site is running TWiki version TWiki-6.1.0, Mon, 16 Jul 2018, build 30610, Plugin API version
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This site is running TWiki version TWiki-6.1.0, Mon, 16 Jul 2018, build 30610, plugin API version
 6.10

%ACTIVATEDPLUGINS%

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On this TWiki site, the enabled Plugins are: SpreadSheetPlugin, BackupRestorePlugin, ColorPickerPlugin, CommentPlugin, DatePickerPlugin, EditTablePlugin, HeadlinesPlugin, InterwikiPlugin, JQueryPlugin, PreferencesPlugin, SetGetPlugin, SlideShowPlugin, SmiliesPlugin, TWikiSheetPlugin, TablePlugin, TagMePlugin, TinyMCEPlugin, TwistyPlugin, WatchlistPlugin, WysiwygPlugin.
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On this TWiki site, the enabled plugins are: SpreadSheetPlugin, BackupRestorePlugin, ColorPickerPlugin, CommentPlugin, DatePickerPlugin, EditTablePlugin, HeadlinesPlugin, InterwikiPlugin, JQueryPlugin, PreferencesPlugin, SetGetPlugin, SlideShowPlugin, SmiliesPlugin, TWikiSheetPlugin, TablePlugin, TagMePlugin, TinyMCEPlugin, TwistyPlugin, WatchlistPlugin, WysiwygPlugin.
 

%PLUGINDESCRIPTIONS%

  • SpreadSheetPlugin (2018-07-05, $Rev: 30478 (2018-07-16) $): Add spreadsheet calculation like "$SUM( $ABOVE() )" to TWiki tables or anywhere in topic text
  • BackupRestorePlugin (2021-03-19, $Rev: 30914 (2021-03-19) $): Administrator utility to backup, restore and upgrade a TWiki site
  • ColorPickerPlugin (2018-07-05, $Rev: 30442 (2018-07-16) $): Color picker, packaged for use in TWiki forms and TWiki applications
  • CommentPlugin (2018-07-05, $Rev: 30530 (2018-07-16) $): Quickly post comments to a page without an edit/preview/save cycle
  • DatePickerPlugin (2018-07-05, $Rev: 30446 (2018-07-16) $): Pop-up calendar with date picker, for use in TWiki forms, HTML forms and TWiki plugins
  • EditTablePlugin (2018-07-05, $Rev: 30448 (2018-07-16) $): Edit TWiki tables using edit fields, date pickers and drop down boxes
  • HeadlinesPlugin (2018-07-13, $Rev: 30560 (2018-07-16) $): Show headline news in TWiki pages based on RSS and ATOM news feeds from external sites
  • InterwikiPlugin (2018-07-05, $Rev: 30454 (2018-07-16) $): Write ExternalSite:Page to link to a page on an external site based on aliases defined in a rules topic
  • JQueryPlugin (2018-07-05, $Rev: 30456 (2018-07-16) $): jQuery JavaScript library for TWiki
  • PreferencesPlugin (2018-07-05, $Rev: 30528 (2018-07-16) $): Allows editing of preferences using fields predefined in a form
  • SetGetPlugin (2018-07-05, $Rev: 30472 (2018-07-16) $): Set and get variables and JSON objects in topics, optionally persistently across topic views
  • SlideShowPlugin (2018-07-05, $Rev: 30474 (2018-07-16) $): Create web based presentations based on topics with headings.
  • SmiliesPlugin (2018-07-05, $Rev: 30476 (2018-07-16) $): Render smilies as icons, like  :-) for smile or  :eek: for eek!
  • TWikiSheetPlugin (2018-07-15, $Rev: 30604 (2018-07-16) $): Add TWiki Sheet spreadsheet functionality to TWiki tables
  • TablePlugin (2018-07-05, $Rev: 30480 (2018-07-16) $): Control attributes of tables and sorting of table columns
  • TagMePlugin (2018-07-05, $Rev: 30482 (2018-07-16) $): Tag wiki content collectively or authoritatively to find content by keywords
  • TinyMCEPlugin (2021-06-09, $Rev: 31045 (2021-06-09) $): Integration of the Tiny MCE WYSIWYG Editor
  • TwistyPlugin (2018-07-06, $Rev: 30497 (2018-07-16) $): Twisty section JavaScript library to open/close content dynamically
  • WatchlistPlugin (2018-07-10, $Rev: 30536 (2018-07-16) $): Watch topics of interest and get notified of changes by e-mail
  • WysiwygPlugin (2018-07-06, $Rev: 30528 (2018-07-16) $): Translator framework for WYSIWYG editors

%FAILEDPLUGINS%

PluginErrors
SpreadSheetPlugin none
BackupRestorePlugin none
ColorPickerPlugin none
CommentPlugin none
DatePickerPlugin none
EditTablePlugin none
HeadlinesPlugin none
InterwikiPlugin none
JQueryPlugin none
PreferencesPlugin none
SetGetPlugin none
SlideShowPlugin none
SmiliesPlugin none
TWikiSheetPlugin none
TablePlugin none
TagMePlugin none
TinyMCEPlugin none
TwistyPlugin none
WatchlistPlugin none
WysiwygPlugin none
HandlerPlugins
afterEditHandlerWysiwygPlugin
afterRenameHandlerTagMePlugin
WatchlistPlugin
afterSaveHandlerTagMePlugin
WatchlistPlugin
beforeCommonTagsHandlerEditTablePlugin
PreferencesPlugin
TWikiSheetPlugin
TwistyPlugin
WysiwygPlugin
beforeEditHandlerTinyMCEPlugin
WysiwygPlugin
beforeMergeHandlerWysiwygPlugin
beforeSaveHandlerCommentPlugin
WatchlistPlugin
WysiwygPlugin
commonTagsHandlerSpreadSheetPlugin
BackupRestorePlugin
CommentPlugin
EditTablePlugin
JQueryPlugin
SlideShowPlugin
SmiliesPlugin
TWikiSheetPlugin
initPluginSpreadSheetPlugin
BackupRestorePlugin
ColorPickerPlugin
CommentPlugin
DatePickerPlugin
EditTablePlugin
HeadlinesPlugin
InterwikiPlugin
JQueryPlugin
PreferencesPlugin
SetGetPlugin
SlideShowPlugin
SmiliesPlugin
TWikiSheetPlugin
TablePlugin
TagMePlugin
TinyMCEPlugin
TwistyPlugin
WatchlistPlugin
WysiwygPlugin
modifyHeaderHandlerWysiwygPlugin
postRenderingHandlerPreferencesPlugin
WysiwygPlugin
preRenderingHandlerInterwikiPlugin
SmiliesPlugin
TablePlugin
20 plugins

The TWiki Plugin API

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The Application Programming Interface (API) for TWiki Plugins provides the specifications for hooking into the core TWiki code from your external Perl Plugin module.
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The Application Programming Interface (API) for TWiki plugins provides the specifications for hooking into the core TWiki code from your external Perl plugin module.
 

Available Core Functions

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The TWikiFuncDotPm module (lib/TWiki/Func.pm) describes all the interfaces available to Plugins. Plugins should only use the interfaces described in this module.
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The TWikiFuncDotPm module (lib/TWiki/Func.pm) describes all the interfaces available to plugins. Plugins should only use the interfaces described in this module.
 
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ALERT! Note: If you use other core functions not described in Func.pm, you run the risk of creating security holes. Also, your Plugin will likely break and require updating when you upgrade to a new version of TWiki.
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ALERT! Note: If you use other core functions not described in Func.pm, you run the risk of creating security holes. Also, your plugin will likely break and require updating when you upgrade to a new version of TWiki.
 

Predefined Hooks

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In addition to TWiki core functions, Plugins can use predefined hooks, or callbacks, as described in the lib/TWiki/Plugins/EmptyPlugin.pm module.
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In addition to TWiki core functions, plugins can use predefined hooks, or callbacks, as described in the lib/TWiki/Plugins/EmptyPlugin.pm module.
 
  • All but the initPlugin are disabled. To enable a callback, remove DISABLE_ from the function name.

TWiki:Codev/StepByStepRenderingOrder helps you decide which rendering handler to use.

Hints on Writing Fast Plugins

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  • Delay initialization as late as possible. For example, if your Plugin is a simple syntax processor, you might delay loading extra Perl modules until you actually see the syntax in the text.
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  • Delay initialization as late as possible. For example, if your plugin is a simple syntax processor, you might delay loading extra Perl modules until you actually see the syntax in the text.
 
    • For example, use an eval block like this:
      eval { require IPC::Run }
      return "<font color=\"red\">SamplePlugin: Can't load required modules ($@)</font>" if $@;
  • Keep the main plugin package as small as possible; create other packages that are loaded if and only if they are used. For example, create sub-packages of BathPlugin in lib/TWiki/Plugins/BathPlugin/.
  • Avoid using preferences in the plugin topic; set $NO_PREFS_IN_TOPIC if you possibly can, as that will stop TWiki from reading the plugin topic for every page. Use Config.spec instead.
  • Use registered tag handlers
  • Measure the performance to see the difference

Version Detection

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To eliminate the incompatibility problems that are bound to arise from active open Plugin development, a Plugin versioning system is provided for automatic compatibility checking.
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To eliminate the incompatibility problems that are bound to arise from active open plugin development, a plugin versioning system is provided for automatic compatibility checking.
 
  • All plugin packages require a $VERSION variable. This should be an integer, or a subversion version id.

  • The initPlugin handler should check all dependencies and return 1 if the initialization is OK or 0 if something went wrong.
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    • The Plugin initialization code does not register a Plugin that returns 0 (or that has no initPlugin handler).
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    • The plugin initialization code does not register a plugin that returns 0 (or that has no initPlugin handler).
 
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  • $TWiki::Plugins::VERSION in the TWiki::Plugins module contains the TWiki Plugin API version, currently 6.10.
    • You can also use the %PLUGINVERSION{}% variable to query the Plugin API version or the version of installed Plugins.
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  • $TWiki::Plugins::VERSION in the TWiki::Plugins module contains the TWiki plugin API version, currently 6.10.
    • You can also use the %PLUGINVERSION{}% variable to query the plugin API version or the version of installed plugins.
 

Security

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  • Badly written Plugins can open huge security holes in TWiki. This is especially true if care isn't taken to prevent execution of arbitrary commands on the server.
  • Don't allow sensitive configuration data to be edited by users. it is better to add sensitive configuration options to the %TWiki::cfg hash than adding it as preferences in the Plugin topic
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  • Badly written plugins can open huge security holes in TWiki. This is especially true if care isn't taken to prevent execution of arbitrary commands on the server.
  • Don't allow sensitive configuration data to be edited by users. it is better to add sensitive configuration options to the %TWiki::cfg hash than adding it as preferences in the plugin topic.
Added:
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  • Always audit the Plugins you install, and make sure you are happy with the level of security provided. While every effort is made to monitor Plugin authors activities, at the end of the day they are uncontrolled user contributions.
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  • Always audit the plugins you install, and make sure you are happy with the level of security provided. While every effort is made to monitor plugin authors activities, at the end of the day they are uncontrolled user contributions.
 

Creating Plugins

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With a reasonable knowledge of the Perl scripting language, you can create new Plugins or modify and extend existing ones. Basic plug-in architecture uses an Application Programming Interface (API), a set of software instructions that allow external code to interact with the main program. The TWiki Plugin API Plugins by providing a programming interface for TWiki.
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With a reasonable knowledge of the Perl scripting language, you can create new plugins or modify and extend existing ones. Basic plug-in architecture uses an Application Programming Interface (API), a set of software instructions that allow external code to interact with the main program. The TWiki Plugin API provides the programming interface for TWiki.
 

Anatomy of a Plugin

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A (very) basic TWiki Plugin consists of two files:
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A (very) basic TWiki plugin consists of two files:
 
  • a Perl module, e.g. MyFirstPlugin.pm
  • a documentation topic, e.g. MyFirstPlugin.txt
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The Perl module can be a block of code that talks to with TWiki alone, or it can include other elements, like other Perl modules (including other Plugins), graphics, TWiki templates, external applications (ex: a Java applet), or just about anything else it can call.
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The Perl module can be a block of code that talks to with TWiki alone, or it can include other elements, like other Perl modules (including other plugins), graphics, TWiki templates, external applications (ex: a Java applet), or just about anything else it can call.
 In particular, files that should be web-accessible (graphics, Java applets ...) are best placed as attachments of the MyFirstPlugin topic. Other needed Perl code is best placed in a lib/TWiki/Plugins/MyFirstPlugin/ directory.
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The Plugin API handles the details of connecting your Perl module with main TWiki code. When you're familiar with the Plugin API, you're ready to develop Plugins.
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The plugin API handles the details of connecting your Perl module with main TWiki code. When you're familiar with the Plugin API, you're ready to develop plugins.
 
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The TWiki::Plugins.BuildContrib module provides a lot of support for plugins development, including a plugin creator, automatic publishing support, and automatic installation script writer. If you plan on writing more than one plugin, you probably need it.
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The TWiki:Plugins.BuildContrib module provides a lot of support for plugins development, including a plugin creator, automatic publishing support, and automatic installation script writer. If you plan on writing more than one plugin, you probably need it.
 

Creating the Perl Module

Copy file lib/TWiki/Plugins/EmptyPlugin.pm to <name>Plugin.pm. The EmptyPlugin.pm module contains mostly empty functions, so it does nothing, but it's ready to be used. Customize it. Refer to the Plugin API specs for more information.

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If your Plugin uses its own modules and objects, you must include the name of the Plugin in the package name. For example, write Package MyFirstPlugin::Attrs; instead of just Package Attrs;. Then call it using:
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If your plugin uses its own modules and objects, you must include the name of the plugin in the package name. For example, write Package MyFirstPlugin::Attrs; instead of just Package Attrs;. Then call it using:
 
use TWiki::Plugins::MyFirstPlugin::Attrs;
$var = MyFirstPlugin::Attrs->new();

Writing the Documentation Topic

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The Plugin documentation topic contains usage instructions and version details. It serves the Plugin files as FileAttachments for downloading. (The doc topic is also included in the distribution package.) To create a documentation topic:
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The plugin documentation topic contains usage instructions and version details. It serves the plugin files as FileAttachments for downloading. (The doc topic is also included in the distribution package.) To create a documentation topic:
 
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  1. Copy the Plugin topic template from TWiki.org. To copy the text, go to TWiki:Plugins/PluginPackage and:
    • enter the Plugin name in the "How to Create a Plugin" section
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  1. Copy the plugin topic template from TWiki.org. To copy the text, go to TWiki:Plugins/PluginPackage and:
    • enter the plugin name in the "How to Create a Plugin" section
 
    • click Create
    • select all in the Edit box & copy
    • Cancel the edit
    • go back to your site to the TWiki web
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    • In the GoBox enter your Plugin name, for example MyFirstPlugin, press enter and create the new topic
    • paste & save new Plugin topic on your site
  1. Customize your Plugin topic.
    • Important: In case you plan to publish your Plugin on TWiki.org, use Interwiki names for author names and links to TWiki.org topics, such as TWiki:Main/TWikiGuest. This is important because links should work properly in a Plugin topic installed on any TWiki, not just on TWiki.org.
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    • In the GoBox enter your plugin name, for example MyFirstPlugin, press enter and create the new topic
    • paste & save new plugin topic on your site
  1. Customize your plugin topic.
    • Important: In case you plan to publish your plugin on TWiki.org, use Interwiki names for author names and links to TWiki.org topics, such as TWiki:Main/TWikiGuest. This is important because links should work properly in a plugin topic installed on any TWiki, not just on TWiki.org.
 
  1. Document the performance data you gathered while measuring the performance
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  1. Save your topic, for use in packaging and publishing your Plugin.
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  1. Save your topic, for use in packaging and publishing your plugin.
 
OUTLINE: Doc Topic Contents
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Check the Plugins web on TWiki.org for the latest Plugin doc topic template. Here's a quick overview of what's covered:
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Check the plugins web on TWiki.org for the latest plugin doc topic template. Here's a quick overview of what's covered:
  Syntax Rules: <Describe any special text formatting that will be rendered.>"
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Example: <Include an example of the Plugin in action. Possibly include a static HTML version of the example to compare if the installation was a success!>"
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Example: <Include an example of the plugin in action. Possibly include a static HTML version of the example to compare if the installation was a success!>"
 
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Plugin Settings: <Description and settings for custom Plugin %VARIABLES%, and those required by TWiki.>"
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Plugin Settings: <Description and settings for custom plugin %VARIABLES%, and those required by TWiki.>"
 
  • Plugins Preferences <If user settings are needed, explain... Entering values works exactly like TWikiPreferences and WebPreferences: six (6) spaces and then:>"
    • Set <EXAMPLE = value added>

Plugin Installation Instructions: <Step-by-step set-up guide, user help, whatever it takes to install and run, goes here.>"

Plugin Info: <Version, credits, history, requirements - entered in a form, displayed as a table. Both are automatically generated when you create or edit a page in the TWiki:Plugins web.>"

Packaging for Distribution

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The TWiki:Plugins.BuildContrib is a powerful build environment that is used by the TWiki project to build TWiki itself, as well as many of the Plugins. You don't have to use it, but it is highly recommended!
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The TWiki:Plugins.BuildContrib is a powerful build environment that is used by the TWiki project to build TWiki itself, as well as many of the plugins. You don't have to use it, but it is highly recommended!
 
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If you don't want (or can't) use the BuildContrib, then a minimum Plugin release consists of a Perl module with a WikiName that ends in Plugin, ex: MyFirstPlugin.pm, and a documentation page with the same name(MyFirstPlugin.txt).
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If you don't want (or can't) use the BuildContrib, then a minimum plugin release consists of a Perl module with a WikiName that ends in Plugin, ex: MyFirstPlugin.pm, and a documentation page with the same name(MyFirstPlugin.txt).
 
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  1. Distribute the Plugin files in a directory structure that mirrors TWiki. If your Plugin uses additional files, include them all:
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  1. Distribute the plugin files in a directory structure that mirrors TWiki. If your plugin uses additional files, include them all:
 
    • lib/TWiki/Plugins/MyFirstPlugin.pm
    • data/TWiki/MyFirstPlugin.txt
    • pub/TWiki/MyFirstPlugin/uparrow.gif [a required graphic]
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  1. Create a zip archive with the Plugin name (MyFirstPlugin.zip) and add the entire directory structure from Step 1. The archive should look like this:
>
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  1. Create a zip archive with the plugin name (MyFirstPlugin.zip) and add the entire directory structure from Step 1. The archive should look like this:
 
    • lib/TWiki/Plugins/MyFirstPlugin.pm
    • data/TWiki/MyFirstPlugin.txt
    • pub/TWiki/MyFirstPlugin/uparrow.gif

Measuring and Improving the Plugin Performance

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A high quality Plugin performs well. You can use the TWiki:Plugins.PluginBenchmarkAddOn to measure your TWiki:Plugins.PluginBenchmarks. The data is needed as part of the Documentation Topic.
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A high quality plugin performs well. You can use the TWiki:Plugins.PluginBenchmarkAddOn to measure your TWiki:Plugins.PluginBenchmarks. The data is needed as part of the Documentation Topic.
  See also Hints on Writing Fast Plugins.

Publishing for Public Use

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You can release your tested, packaged Plugin to the TWiki community through the TWiki:Plugins web. All Plugins submitted to TWiki.org are available for download and further development in TWiki:Plugins/PluginPackage.
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You can release your tested, packaged plugin to the TWiki community through the TWiki:Plugins web. All plugins submitted to TWiki.org are available for download and further development in TWiki:Plugins/PluginPackage.
 
Changed:
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Publish your Plugin by following these steps:
  1. Post the Plugin documentation topic in the TWiki:Plugins/PluginPackage:
    • enter the Plugin name in the "How to Create a Plugin" section, for example MyFirstPlugin
>
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Publish your plugin by following these steps:
  1. Post the plugin documentation topic in the TWiki:Plugins/PluginPackage:
    • enter the plugin name in the "How to Create a Plugin" section, for example MyFirstPlugin
 
  1. Attach the distribution zip file to the topic, ex: MyFirstPlugin.zip
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  1. Link from the doc page to a new, blank page named after the Plugin, and ending in Dev, ex: MyFirstPluginDev. This is the discussion page for future development. (User support for Plugins is handled in TWiki:Support.)
  2. Put the Plugin into the SVN repository, see TWiki:Plugins/ReadmeFirst (optional)
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  1. Link from the doc page to a new, blank page named after the plugin, and ending in Dev, ex: MyFirstPluginDev. This is the discussion page for future development. (User support for plugins is handled in TWiki:Support.)
  2. Put the plugin into the SVN repository, see TWiki:Plugins/ReadmeFirst (optional)
 
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NEW Once you have done the above steps once, you can use the BuildContrib to upload updates to your Plugin.
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NEW Once you have done the above steps once, you can use the BuildContrib to upload updates to your plugin.
 
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Thank you very much for sharing your Plugin with the TWiki community smile
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Thank you very much for sharing your plugin with the TWiki community smile
 

Recommended Storage of Plugin Specific Data

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Plugins sometimes need to store data. This can be Plugin internal data such as cache data, or data generated for browser consumption such as images. Plugins should store data using TWikiFuncDotPm functions that support saving and loading of topics and attachments.
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Plugins sometimes need to store data. This can be plugin internal data such as cache data, or data generated for browser consumption such as images. Plugins should store data using TWikiFuncDotPm functions that support saving and loading of topics and attachments.
 

Plugin Internal Data

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You can create a Plugin "work area" using the TWiki::Func::getWorkArea() function, which gives you a persistent directory where you can store data files. By default they will not be web accessible. The directory is guaranteed to exist, and to be writable by the webserver user. For convenience, TWiki::Func::storeFile() and TWiki::Func::readFile() are provided to persistently store and retrieve simple data in this area.
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You can create a plugin "work area" using the TWiki::Func::getWorkArea() function, which gives you a persistent directory where you can store data files. By default they will not be web accessible. The directory is guaranteed to exist, and to be writable by the webserver user. For convenience, TWiki::Func::storeFile() and TWiki::Func::readFile() are provided to persistently store and retrieve simple data in this area.
 

Web Accessible Data

Topic-specific data such as generated images can be stored in the topic's attachment area, which is web accessible. Use the TWiki::Func::saveAttachment() function to store the data.

Recommendation for file name:

  • Prefix the filename with an underscore (the leading underscore avoids a name clash with files attached to the same topic)
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  • Identify where the attachment originated from, typically by including the Plugin name in the file name
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  • Identify where the attachment originated from, typically by including the plugin name in the file name
 
  • Use only alphanumeric characters, underscores, dashes and periods to avoid platform dependency issues and URL issues
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  • Example: _FooBarPlugin_img123.gif
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  • Example: _GaugePlugin_img123.gif
 
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Web specific data can be stored in the Plugin's attachment area, which is web accessible. Use the TWiki::Func::saveAttachment() function to store the data.
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Web specific data can be stored in the plugin's attachment area, which is web accessible. Use the TWiki::Func::saveAttachment() function to store the data.
 
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Recommendation for file names in Plugin attachment area:
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Recommendation for file names in plugin attachment area:
 
  • Prefix the filename with an underscore
  • Include the name of the web in the filename
  • Use only alphanumeric characters, underscores, dashes and periods to avoid platform dependency issues and URL issues
  • Example: _Main_roundedge-ul.gif

Integrating with configure

Some TWiki extensions have setup requirements that are best integrated into configure rather than trying to use TWiki preferences variables. These extensions use Config.spec files to publish their configuration requirements.

Config.spec files are read during TWiki configuration. Once a Config.spec has defined a configuration item, it is available for edit through the standard configure interface. Config.spec files are stored in the 'plugin directory' e.g. lib/TWiki/Plugins/BathPlugin/Config.spec.

Structure of a Config.spec file

The Config.spec file for a plugin starts with the plugin announcing what it is:
# ---+ BathPlugin
# This plugin senses the level of water in your bath, and ensures the plug
# is not removed while the water is still warm.
This is followed by one or more configuration items. Each configuration item has a type, a description and a default. For example:
# **SELECT Plastic,Rubber,Metal**
# Select the plug type
$TWiki::cfg{BathPlugin}{PlugType} = 'Plastic';

# **NUMBER**
# Enter the chain length in cm
$TWiki::cfg{BathPlugin}{ChainLength} = '30';

# **BOOLEAN EXPERT**
# Turn this option off to disable the water temperature alarm
$TWiki::cfg{BathPlugin}{TempSensorEnabled} = '1';
The type (e.g. **SELECT** ) tells configure to how to prompt for the value. It also tells configure how to do some basic checking on the value you actually enter. All the comments between the type and the configuration item are taken as part of the description. The configuration item itself defines the default value for the configuration item. The above spec defines the configuration items $TWiki::cfg{BathPlugin}{PlugType}, $TWiki::cfg{BathPlugin}{ChainLength}, and $TWiki::cfg{BathPlugin}{TempSensorEnabled} for use in your plugin. For example,
if( $TWiki::cfg{BathPlugin}{TempSensorEnabled} && $curTemperature > 50 ) {
    die "The bathwater is too hot for comfort";
}

The config.spec file is read by configure, and configure then writes LocalSite.cfg with the values chosen by the local site admin.

A range of types are available for use in Config.spec files:

BOOLEAN A true/false value, represented as a checkbox
COMMAND length A shell command
LANGUAGE A language (selected from {LocalesDir}
NUMBER A number
OCTAL An octal number
PASSWORD length A password (input is hidden)
PATH length A file path
PERL A perl structure, consisting of arrays and hashes
REGEX length A perl regular expression
SELECT choices Pick one of a range of choices
SELECTCLASS root Select a perl package (class)
STRING length A string
URL length A url
URLPATH length A relative URL path

All types can be followed by a comma-separated list of attributes.

EXPERT means this an expert option
M means the setting is mandatory (may not be empty)
H means the option is not visible in configure

See lib/TWiki.spec for many more examples.

Config.spec files are also used for other (non-plugin) extensions. in this case they are stored under the Contrib directory instead of the Plugins directory.

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TWiki:TWiki/SpecifyingConfigurationItemsForExtensions has supplemental documentation on configure settings.
 

Maintaining Plugins

Discussions and Feedback on Plugins

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Each published Plugin has a Plugin development topic on TWiki.org. Plugin development topics are named after your Plugin and end in Dev, such as MyFirstPluginDev. The Plugin development topic is a great resource to discuss feature enhancements and to get feedback from the TWiki community.
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Each published plugin has a plugin development topic on TWiki.org. Plugin development topics are named after your plugin and end in Dev, such as MyFirstPluginDev. The plugin development topic is a great resource to discuss feature enhancements and to get feedback from the TWiki community.
 

Maintaining Compatibility with Earlier TWiki Versions

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The Plugin interface (TWikiFuncDotPm functions and handlers) evolve over time. TWiki 4.0 introduced new API functions to address the needs of Plugin authors. It also deprecated some functions. Some Plugins written for earlier TWiki releases using unofficial TWiki internal functions no longer work on the TWiki 4.0 codebase. All this means that some Plugins need to be updated to work on the TWiki 4.0 codebase.
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The plugin interface (TWikiFuncDotPm functions and plugin handlers) evolve over time. TWiki introduces new API functions to address the needs of plugin authors. Plugins using unofficial TWiki internal functions may no longer work on a TWiki upgrade.
 
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Organizations typically do not upgrade to the latest TWiki for many months. However, many administrators still would like to install the latest versions of a Plugin on their older TWiki installation. This need is fulfilled if Plugins are maintained in a compatible manner.
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Organizations typically do not upgrade to the latest TWiki for many months. However, many administrators still would like to install the latest versions of a plugin on their older TWiki installation. This need is fulfilled if plugins are maintained in a compatible manner.
 
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TIP Tip: Plugins can be written to be compatible with older and newer TWiki releases. This can be done also for Plugins using unofficial TWiki internal functions of an earlier release that no longer work on the latest TWiki codebase. TWiki:TWiki.TWikiPluginsSupplement#MaintainPlugins has more.
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TIP Tip: Plugins can be written to be compatible with older and newer TWiki releases. This can be done also for plugins using unofficial TWiki internal functions of an earlier release that no longer work on the latest TWiki codebase.
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Here is an example; the TWiki:TWiki.TWikiPluginsSupplement#MaintainPlugins has more details.
 
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    if( $TWiki::Plugins::VERSION >= 1.1 ) {
        @webs = TWiki::Func::getListOfWebs( 'user,public' );
    } else {
        @webs = TWiki::Func::getPublicWebList( );
    }
 

Handling deprecated functions

From time-to-time, the TWiki developers will add new functions to the interface (either to TWikiFuncDotPm, or new handlers). Sometimes these improvements mean that old functions have to be deprecated to keep the code manageable. When this happens, the deprecated functions will be supported in the interface for at least one more TWiki release, and probably longer, though this cannot be guaranteed.

When a plugin defines deprecated handlers, a warning will be shown in the list generated by %FAILEDPLUGINS%. Admins who see these warnings should check TWiki.org and if necessary, contact the plugin author, for an updated version of the plugin.

Updated plugins may still need to define deprecated handlers for compatibility with old TWiki versions. In this case, the plugin package that defines old handlers can suppress the warnings in %FAILEDPLUGINS%.

This is done by defining a map from the handler name to the TWiki::Plugins version in which the handler was first deprecated. For example, if we need to define the endRenderingHandler for compatibility with TWiki::Plugins versions before 1.1, we would add this to the plugin:

package TWiki::Plugins::SinkPlugin;
use vars qw( %TWikiCompatibility );
$TWikiCompatibility{endRenderingHandler} = 1.1;
If the currently-running TWiki version is 1.1 or later, then the handler will not be called and the warning will not be issued. TWiki with versions of TWiki::Plugins before 1.1 will still call the handler as required.

Related Topics: DeveloperDocumentationCategory, AdminDocumentationCategory, TWiki:TWiki.TWikiPluginsSupplement

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-- Contributors: TWiki:Main.PeterThoeny, TWiki:Main.AndreaSterbini, TWiki:Main.MikeMannix, TWiki:Main.CrawfordCurrie, TWiki:Main.ArthurClemens, TWiki:Main.WillNorris
 

Revision 332007-05-16 - TWikiContributor

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TWiki Plugins

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TWiki Plugins

  Add functionality to TWiki with readily available Plugins; create Plugins based on APIs
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Overview

You can add Plugins to extend TWiki functionality, without altering the core code. A plug-in approach lets you:

  • add virtually unlimited features while keeping the main TWiki code compact and efficient;
  • heavily customize an installation and still do clean updates to new versions of TWiki;
  • rapidly develop new TWiki functions in Perl using the Plugin API.

Everything to do with TWiki Plugins - demos, new releases, downloads, development, general discussion - is available at TWiki.org, in the TWiki:Plugins web.

TWiki Plugins are developed and contributed by interested members of the community. Plugins are provided on an 'as is' basis; they are not a part of TWiki, but are independently developed and maintained.

Relevant links on TWiki.org:

See other types of extensions: TWikiAddOns, TWikiContribs, TWikiSkins

Installing Plugins

Each TWiki Plugin comes with its own documentation: step-by-step installation instructions, a detailed description of any special requirements, version details, and a working example for testing. Many Plugins have an install script that automates these steps for you.

Special Requirements: Some Plugins need certain Perl modules to be preinstalled on the host system. Plugins may also use other resources, like graphics, other modules, applications, and templates. You should be able to find detailed instructions in the Plugin's documentation.

Each Plugin has a standard release topic, located in the TWiki:Plugins web at TWiki.org. There's usually a number of other related topics, such as a developers page, and an appraisal page.

On-Site Pretesting

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The recommended approach to testing new Plugins before making them public is to create a second local TWiki installation, and test the Plugin there. You can allow selected users access to the test area. Once you are satisifed that it won't compromise your main installation, you can install it there as well.
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The recommended approach to testing new Plugins before making them public is to create a second local TWiki installation, and test the Plugin there. You can allow selected users access to the test area. Once you are satisfied that it won't compromise your main installation, you can install it there as well.
  InstalledPlugins shows which Plugins are: 1) installed, 2) loading properly, and 3) what TWiki:Codev.PluginHandlers they invoke. Any failures are shown in the Errors section. The %FAILEDPLUGINS% variable can be used to debug failures. You may also want to check your webserver error log and the various TWiki log files.

Some Notes on Plugin Performance

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The performance of the system depends to some extent on the number of Plugins installed and on the Plugin implementation. Some Plugins impose no measurable performance decrease, some do. For example, a Plugin might use many Perl libraries that need to be initialized with each page view (unless you run mod_perl). You can only really tell the performance impact by installing the Plugin and by measuring the performance with and without the new Plugin. Use the TWiki:Plugins.PluginBenchmarkAddOn, or test manually with the Apache ab utility. Example on Unix:
time wget -qO /dev/null /twiki/bin/view/TWiki/AbcPlugin
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The performance of the system depends to some extent on the number of Plugins installed and on the Plugin implementation. Some Plugins impose no measurable performance decrease, some do. For example, a Plugin might use many Perl libraries that need to be initialized with each page view (unless you run mod_perl). You can only really tell the performance impact by installing the Plugin and by measuring the performance with and without the new Plugin. Use the TWiki:Plugins.PluginBenchmarkAddOn, or test manually with the Apache ab utility. Example on Unix:
time wget -qO /dev/null /twiki/bin/view/TWiki/AbcPlugin
  TIP If you need to install an "expensive" Plugin, but you only need its functionality only in a subset of your data, you can disable it elsewhere by defining the %DISABLEDPLUGINS% TWiki variable.
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Define DISABLEDPLUGINS to be a comma-separated list of names of plugins to disable. Define it in Main.TWikiPreferences to disable those plugins everywhere, in the WebPreferences topic to disable them in an individual web, or in a topic to disable them in that topic. For example,
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Define DISABLEDPLUGINS to be a comma-separated list of names of plugins to disable. Define it in Main.TWikiPreferences to disable those plugins everywhere, in the WebPreferences topic to disable them in an individual web, or in a topic to disable them in that topic. For example,
 
   * Set DISABLEDPLUGINS = SpreadSheetPlugin, EditTablePlugin

Managing Installed Plugins

Some Plugins require additional settings or offer extra options that you have to select. Also, you may want to make a Plugin available only in certain webs, or temporarily disable it. And may want to list all available Plugins in certain topics. You can handle all of these management tasks with simple procedures:

Enabling Plugins

Plugins can be enabled and disabled with the configure script. An installed Plugin needs to be enabled before it can be used.

Plugin Evaluation Order

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By default, TWiki executes Plugins in alphabetical order on Plugin name. It is possible to change the order, for example to evaluate database variables before the speadsheet CALCs. This can be done with {PluginsOrder} in the Plugins section of configure.
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By default, TWiki executes Plugins in alphabetical order on Plugin name. It is possible to change the order, for example to evaluate database variables before the spreadsheet CALCs. This can be done with {PluginsOrder} in the Plugins section of configure.
 

Plugin-Specific Settings

Plugins are usually configured by variables accessible though the configure interface, but in some cases (usually older plugins) TWiki preferences are used. If a TWiki variable is defined in a Plugin topic e.g:

  • Set SETTING = Create dynamic foo bar reports
Then these settings can be retrieved as preferences variables like %<pluginname>_<var>%. For example, %RUBBERPLUGIN_SETTING% shows the value of SETTING in the RubberPlugin topic.

Listing Active Plugins

Plugin status variables let you list all active Plugins wherever needed.

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This site is running TWiki version TWiki-6.1.0, Mon, 16 Jul 2018, build 30610, Plugin API version 6.10

 

%ACTIVATEDPLUGINS%

On this TWiki site, the enabled Plugins are: SpreadSheetPlugin, BackupRestorePlugin, ColorPickerPlugin, CommentPlugin, DatePickerPlugin, EditTablePlugin, HeadlinesPlugin, InterwikiPlugin, JQueryPlugin, PreferencesPlugin, SetGetPlugin, SlideShowPlugin, SmiliesPlugin, TWikiSheetPlugin, TablePlugin, TagMePlugin, TinyMCEPlugin, TwistyPlugin, WatchlistPlugin, WysiwygPlugin.

%PLUGINDESCRIPTIONS%

  • SpreadSheetPlugin (2018-07-05, $Rev: 30478 (2018-07-16) $): Add spreadsheet calculation like "$SUM( $ABOVE() )" to TWiki tables or anywhere in topic text
  • BackupRestorePlugin (2021-03-19, $Rev: 30914 (2021-03-19) $): Administrator utility to backup, restore and upgrade a TWiki site
  • ColorPickerPlugin (2018-07-05, $Rev: 30442 (2018-07-16) $): Color picker, packaged for use in TWiki forms and TWiki applications
  • CommentPlugin (2018-07-05, $Rev: 30530 (2018-07-16) $): Quickly post comments to a page without an edit/preview/save cycle
  • DatePickerPlugin (2018-07-05, $Rev: 30446 (2018-07-16) $): Pop-up calendar with date picker, for use in TWiki forms, HTML forms and TWiki plugins
  • EditTablePlugin (2018-07-05, $Rev: 30448 (2018-07-16) $): Edit TWiki tables using edit fields, date pickers and drop down boxes
  • HeadlinesPlugin (2018-07-13, $Rev: 30560 (2018-07-16) $): Show headline news in TWiki pages based on RSS and ATOM news feeds from external sites
  • InterwikiPlugin (2018-07-05, $Rev: 30454 (2018-07-16) $): Write ExternalSite:Page to link to a page on an external site based on aliases defined in a rules topic
  • JQueryPlugin (2018-07-05, $Rev: 30456 (2018-07-16) $): jQuery JavaScript library for TWiki
  • PreferencesPlugin (2018-07-05, $Rev: 30528 (2018-07-16) $): Allows editing of preferences using fields predefined in a form
  • SetGetPlugin (2018-07-05, $Rev: 30472 (2018-07-16) $): Set and get variables and JSON objects in topics, optionally persistently across topic views
  • SlideShowPlugin (2018-07-05, $Rev: 30474 (2018-07-16) $): Create web based presentations based on topics with headings.
  • SmiliesPlugin (2018-07-05, $Rev: 30476 (2018-07-16) $): Render smilies as icons, like  :-) for smile or  :eek: for eek!
  • TWikiSheetPlugin (2018-07-15, $Rev: 30604 (2018-07-16) $): Add TWiki Sheet spreadsheet functionality to TWiki tables
  • TablePlugin (2018-07-05, $Rev: 30480 (2018-07-16) $): Control attributes of tables and sorting of table columns
  • TagMePlugin (2018-07-05, $Rev: 30482 (2018-07-16) $): Tag wiki content collectively or authoritatively to find content by keywords
  • TinyMCEPlugin (2021-06-09, $Rev: 31045 (2021-06-09) $): Integration of the Tiny MCE WYSIWYG Editor
  • TwistyPlugin (2018-07-06, $Rev: 30497 (2018-07-16) $): Twisty section JavaScript library to open/close content dynamically
  • WatchlistPlugin (2018-07-10, $Rev: 30536 (2018-07-16) $): Watch topics of interest and get notified of changes by e-mail
  • WysiwygPlugin (2018-07-06, $Rev: 30528 (2018-07-16) $): Translator framework for WYSIWYG editors
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%FAILEDPLUGINS%

PluginErrors
SpreadSheetPlugin none
BackupRestorePlugin none
ColorPickerPlugin none
CommentPlugin none
DatePickerPlugin none
EditTablePlugin none
HeadlinesPlugin none
InterwikiPlugin none
JQueryPlugin none
PreferencesPlugin none
SetGetPlugin none
SlideShowPlugin none
SmiliesPlugin none
TWikiSheetPlugin none
TablePlugin none
TagMePlugin none
TinyMCEPlugin none
TwistyPlugin none
WatchlistPlugin none
WysiwygPlugin none
HandlerPlugins
afterEditHandlerWysiwygPlugin
afterRenameHandlerTagMePlugin
WatchlistPlugin
afterSaveHandlerTagMePlugin
WatchlistPlugin
beforeCommonTagsHandlerEditTablePlugin
PreferencesPlugin
TWikiSheetPlugin
TwistyPlugin
WysiwygPlugin
beforeEditHandlerTinyMCEPlugin
WysiwygPlugin
beforeMergeHandlerWysiwygPlugin
beforeSaveHandlerCommentPlugin
WatchlistPlugin
WysiwygPlugin
commonTagsHandlerSpreadSheetPlugin
BackupRestorePlugin
CommentPlugin
EditTablePlugin
JQueryPlugin
SlideShowPlugin
SmiliesPlugin
TWikiSheetPlugin
initPluginSpreadSheetPlugin
BackupRestorePlugin
ColorPickerPlugin
CommentPlugin
DatePickerPlugin
EditTablePlugin
HeadlinesPlugin
InterwikiPlugin
JQueryPlugin
PreferencesPlugin
SetGetPlugin
SlideShowPlugin
SmiliesPlugin
TWikiSheetPlugin
TablePlugin
TagMePlugin
TinyMCEPlugin
TwistyPlugin
WatchlistPlugin
WysiwygPlugin
modifyHeaderHandlerWysiwygPlugin
postRenderingHandlerPreferencesPlugin
WysiwygPlugin
preRenderingHandlerInterwikiPlugin
SmiliesPlugin
TablePlugin
20 plugins

The TWiki Plugin API

The Application Programming Interface (API) for TWiki Plugins provides the specifications for hooking into the core TWiki code from your external Perl Plugin module.

Available Core Functions

The TWikiFuncDotPm module (lib/TWiki/Func.pm) describes all the interfaces available to Plugins. Plugins should only use the interfaces described in this module.

ALERT! Note: If you use other core functions not described in Func.pm, you run the risk of creating security holes. Also, your Plugin will likely break and require updating when you upgrade to a new version of TWiki.

Predefined Hooks

In addition to TWiki core functions, Plugins can use predefined hooks, or callbacks, as described in the lib/TWiki/Plugins/EmptyPlugin.pm module.

  • All but the initPlugin are disabled. To enable a callback, remove DISABLE_ from the function name.

TWiki:Codev/StepByStepRenderingOrder helps you decide which rendering handler to use.

Hints on Writing Fast Plugins

  • Delay initialization as late as possible. For example, if your Plugin is a simple syntax processor, you might delay loading extra Perl modules until you actually see the syntax in the text.
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  • For example, use an eval block like this:
    eval { require IPC::Run }
    return "<font color=\"red\">SamplePlugin: Can't load required modules ($@)</font>" if $@;
  • You can use a flag to avoid running the initialization twice
  • The TWiki:Plugins.PluginBenchmarkAddOn comes in handy to measure and fine-tune the performance of your Plugin
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    • For example, use an eval block like this:
      eval { require IPC::Run }
      return "<font color=\"red\">SamplePlugin: Can't load required modules ($@)</font>" if $@;
  • Keep the main plugin package as small as possible; create other packages that are loaded if and only if they are used. For example, create sub-packages of BathPlugin in lib/TWiki/Plugins/BathPlugin/.
  • Avoid using preferences in the plugin topic; set $NO_PREFS_IN_TOPIC if you possibly can, as that will stop TWiki from reading the plugin topic for every page. Use Config.spec instead.
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Plugin Version Detection

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Version Detection

 
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To eliminate the incompatibility problems bound to arise from active open Plugin development, a Plugin versioning system is provided for automatic compatibility checking.
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To eliminate the incompatibility problems that are bound to arise from active open Plugin development, a Plugin versioning system is provided for automatic compatibility checking.
 
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  • All modules require a $VERSION='0.000' variable, beginning at 1.000.
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  • All plugin packages require a $VERSION variable. This should be an integer, or a subversion version id.
 
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  • The initPlugin handler should check all dependencies and return TRUE if the initialization is OK or FALSE if something went wrong.
    • The Plugin initialization code does not register a Plugin that returns FALSE (or that has no initPlugin handler).
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  • The initPlugin handler should check all dependencies and return 1 if the initialization is OK or 0 if something went wrong.
    • The Plugin initialization code does not register a Plugin that returns 0 (or that has no initPlugin handler).
 
  • $TWiki::Plugins::VERSION in the TWiki::Plugins module contains the TWiki Plugin API version, currently 6.10.
    • You can also use the %PLUGINVERSION{}% variable to query the Plugin API version or the version of installed Plugins.

Security

  • Badly written Plugins can open huge security holes in TWiki. This is especially true if care isn't taken to prevent execution of arbitrary commands on the server.
  • Don't allow sensitive configuration data to be edited by users. it is better to add sensitive configuration options to the %TWiki::cfg hash than adding it as preferences in the Plugin topic
  • Always use the TWiki::Sandbox to execute commands.
  • Always audit the Plugins you install, and make sure you are happy with the level of security provided. While every effort is made to monitor Plugin authors activities, at the end of the day they are uncontrolled user contributions.

Creating Plugins

With a reasonable knowledge of the Perl scripting language, you can create new Plugins or modify and extend existing ones. Basic plug-in architecture uses an Application Programming Interface (API), a set of software instructions that allow external code to interact with the main program. The TWiki Plugin API Plugins by providing a programming interface for TWiki.

Anatomy of a Plugin

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A basic TWiki Plugin consists of two elements:
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A (very) basic TWiki Plugin consists of two files:
 
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  • a Perl module, ex: MyFirstPlugin.pm
  • a documentation topic, ex: MyFirstPlugin.txt
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  • a Perl module, e.g. MyFirstPlugin.pm
  • a documentation topic, e.g. MyFirstPlugin.txt
 
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The Perl module can be a block of code that connects with TWiki alone, or it can include other elements, like other Perl modules (including other Plugins), graphics, TWiki templates, external applications (ex: a Java applet), or just about anything else it can call.
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The Perl module can be a block of code that talks to with TWiki alone, or it can include other elements, like other Perl modules (including other Plugins), graphics, TWiki templates, external applications (ex: a Java applet), or just about anything else it can call.
 In particular, files that should be web-accessible (graphics, Java applets ...) are best placed as attachments of the MyFirstPlugin topic. Other needed Perl code is best placed in a lib/TWiki/Plugins/MyFirstPlugin/ directory.

The Plugin API handles the details of connecting your Perl module with main TWiki code. When you're familiar with the Plugin API, you're ready to develop Plugins.

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The TWiki::Plugins.BuildContrib module provides a lot of support for plugins development, including a plugin creator, automatic publishing support, and automatic installation script writer. If you plan on writing more than one plugin, you probably need it.
 

Creating the Perl Module

Copy file lib/TWiki/Plugins/EmptyPlugin.pm to <name>Plugin.pm. The EmptyPlugin.pm module contains mostly empty functions, so it does nothing, but it's ready to be used. Customize it. Refer to the Plugin API specs for more information.

If your Plugin uses its own modules and objects, you must include the name of the Plugin in the package name. For example, write Package MyFirstPlugin::Attrs; instead of just Package Attrs;. Then call it using:

use TWiki::Plugins::MyFirstPlugin::Attrs;
$var = MyFirstPlugin::Attrs->new();
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Measuring and Improving the Plugin Performance

A high quality Plugin performs well. You can use the TWiki:Plugins.PluginBenchmarkAddOn to measure your TWiki:Plugins.PluginBenchmarks. The data is needed as part of the Documentation Topic.

See also Hints on Writing Fast Plugins.

 

Writing the Documentation Topic

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The Plugin documentation topic contains usage instructions and version details. It serves the Plugin files as FileAttachments for downloading. (The doc topic is also included in the distribution package.) To create a documentation topic:
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The Plugin documentation topic contains usage instructions and version details. It serves the Plugin files as FileAttachments for downloading. (The doc topic is also included in the distribution package.) To create a documentation topic:
 
  1. Copy the Plugin topic template from TWiki.org. To copy the text, go to TWiki:Plugins/PluginPackage and:
    • enter the Plugin name in the "How to Create a Plugin" section
    • click Create
    • select all in the Edit box & copy
    • Cancel the edit
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    • go back to your site to the TWiki web
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    • go back to your site to the TWiki web
 
    • In the GoBox enter your Plugin name, for example MyFirstPlugin, press enter and create the new topic
    • paste & save new Plugin topic on your site
  1. Customize your Plugin topic.
    • Important: In case you plan to publish your Plugin on TWiki.org, use Interwiki names for author names and links to TWiki.org topics, such as TWiki:Main/TWikiGuest. This is important because links should work properly in a Plugin topic installed on any TWiki, not just on TWiki.org.
  2. Document the performance data you gathered while measuring the performance
  3. Save your topic, for use in packaging and publishing your Plugin.

OUTLINE: Doc Topic Contents
Check the Plugins web on TWiki.org for the latest Plugin doc topic template. Here's a quick overview of what's covered:

Syntax Rules: <Describe any special text formatting that will be rendered.>"

Example: <Include an example of the Plugin in action. Possibly include a static HTML version of the example to compare if the installation was a success!>"

Plugin Settings: <Description and settings for custom Plugin %VARIABLES%, and those required by TWiki.>"

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  • Plugins Preferences <If user settings are needed, explain... Entering values works exactly like TWikiPreferences and WebPreferences: six (6) spaces and then:>"
>
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  • Plugins Preferences <If user settings are needed, explain... Entering values works exactly like TWikiPreferences and WebPreferences: six (6) spaces and then:>"
 
    • Set <EXAMPLE = value added>

Plugin Installation Instructions: <Step-by-step set-up guide, user help, whatever it takes to install and run, goes here.>"

Plugin Info: <Version, credits, history, requirements - entered in a form, displayed as a table. Both are automatically generated when you create or edit a page in the TWiki:Plugins web.>"

Packaging for Distribution

The TWiki:Plugins.BuildContrib is a powerful build environment that is used by the TWiki project to build TWiki itself, as well as many of the Plugins. You don't have to use it, but it is highly recommended!

If you don't want (or can't) use the BuildContrib, then a minimum Plugin release consists of a Perl module with a WikiName that ends in Plugin, ex: MyFirstPlugin.pm, and a documentation page with the same name(MyFirstPlugin.txt).

  1. Distribute the Plugin files in a directory structure that mirrors TWiki. If your Plugin uses additional files, include them all:
    • lib/TWiki/Plugins/MyFirstPlugin.pm
    • data/TWiki/MyFirstPlugin.txt
    • pub/TWiki/MyFirstPlugin/uparrow.gif [a required graphic]
  2. Create a zip archive with the Plugin name (MyFirstPlugin.zip) and add the entire directory structure from Step 1. The archive should look like this:
    • lib/TWiki/Plugins/MyFirstPlugin.pm
    • data/TWiki/MyFirstPlugin.txt
    • pub/TWiki/MyFirstPlugin/uparrow.gif
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Measuring and Improving the Plugin Performance

A high quality Plugin performs well. You can use the TWiki:Plugins.PluginBenchmarkAddOn to measure your TWiki:Plugins.PluginBenchmarks. The data is needed as part of the Documentation Topic.

See also Hints on Writing Fast Plugins.

 

Publishing for Public Use

You can release your tested, packaged Plugin to the TWiki community through the TWiki:Plugins web. All Plugins submitted to TWiki.org are available for download and further development in TWiki:Plugins/PluginPackage.

Publish your Plugin by following these steps:

  1. Post the Plugin documentation topic in the TWiki:Plugins/PluginPackage:
    • enter the Plugin name in the "How to Create a Plugin" section, for example MyFirstPlugin
    • paste in the topic text from Writing the Documentation Topic and save
  2. Attach the distribution zip file to the topic, ex: MyFirstPlugin.zip
  3. Link from the doc page to a new, blank page named after the Plugin, and ending in Dev, ex: MyFirstPluginDev. This is the discussion page for future development. (User support for Plugins is handled in TWiki:Support.)
  4. Put the Plugin into the SVN repository, see TWiki:Plugins/ReadmeFirst (optional)

NEW Once you have done the above steps once, you can use the BuildContrib to upload updates to your Plugin.

Thank you very much for sharing your Plugin with the TWiki community smile

Recommended Storage of Plugin Specific Data

Plugins sometimes need to store data. This can be Plugin internal data such as cache data, or data generated for browser consumption such as images. Plugins should store data using TWikiFuncDotPm functions that support saving and loading of topics and attachments.

Plugin Internal Data

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You can create a Plugin "work area" using the TWiki::Func::getWorkArea() function, which gives you a persistant directory where you can store data files. By default they will not be web accessible. The directory is guaranteed to exist, and to be writable by the webserver user. For convenience, TWiki::Func::storeFile() and TWiki::Func::readFile() are provided to persistently store and retrieve simple data in this area.
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You can create a Plugin "work area" using the TWiki::Func::getWorkArea() function, which gives you a persistent directory where you can store data files. By default they will not be web accessible. The directory is guaranteed to exist, and to be writable by the webserver user. For convenience, TWiki::Func::storeFile() and TWiki::Func::readFile() are provided to persistently store and retrieve simple data in this area.
 

Web Accessible Data

Topic-specific data such as generated images can be stored in the topic's attachment area, which is web accessible. Use the TWiki::Func::saveAttachment() function to store the data.

Recommendation for file name:

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  • Prefix the filename with an underscore (the leading underscore avoids a nameclash with files attached to the same topic)
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  • Prefix the filename with an underscore (the leading underscore avoids a name clash with files attached to the same topic)
 
  • Identify where the attachment originated from, typically by including the Plugin name in the file name
  • Use only alphanumeric characters, underscores, dashes and periods to avoid platform dependency issues and URL issues
  • Example: _FooBarPlugin_img123.gif

Web specific data can be stored in the Plugin's attachment area, which is web accessible. Use the TWiki::Func::saveAttachment() function to store the data.

Recommendation for file names in Plugin attachment area:

  • Prefix the filename with an underscore
  • Include the name of the web in the filename
  • Use only alphanumeric characters, underscores, dashes and periods to avoid platform dependency issues and URL issues
  • Example: _Main_roundedge-ul.gif
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Integrating with configure

Some TWiki extensions have setup requirements that are best integrated into configure rather than trying to use TWiki preferences variables. These extensions use Config.spec files to publish their configuration requirements.

Config.spec files are read during TWiki configuration. Once a Config.spec has defined a configuration item, it is available for edit through the standard configure interface. Config.spec files are stored in the 'plugin directory' e.g. lib/TWiki/Plugins/BathPlugin/Config.spec.

Structure of a Config.spec file

The Config.spec file for a plugin starts with the plugin announcing what it is:
# ---+ BathPlugin
# This plugin senses the level of water in your bath, and ensures the plug
# is not removed while the water is still warm.
This is followed by one or more configuration items. Each configuration item has a type, a description and a default. For example:
# **SELECT Plastic,Rubber,Metal**
# Select the plug type
$TWiki::cfg{BathPlugin}{PlugType} = 'Plastic';

# **NUMBER**
# Enter the chain length in cm
$TWiki::cfg{BathPlugin}{ChainLength} = '30';

# **BOOLEAN EXPERT**
# Turn this option off to disable the water temperature alarm
$TWiki::cfg{BathPlugin}{TempSensorEnabled} = '1';
The type (e.g. **SELECT** ) tells configure to how to prompt for the value. It also tells configure how to do some basic checking on the value you actually enter. All the comments between the type and the configuration item are taken as part of the description. The configuration item itself defines the default value for the configuration item. The above spec defines the configuration items $TWiki::cfg{BathPlugin}{PlugType}, $TWiki::cfg{BathPlugin}{ChainLength}, and $TWiki::cfg{BathPlugin}{TempSensorEnabled} for use in your plugin. For example,
if( $TWiki::cfg{BathPlugin}{TempSensorEnabled} && $curTemperature > 50 ) {
    die "The bathwater is too hot for comfort";
}

The config.spec file is read by configure, and configure then writes LocalSite.cfg with the values chosen by the local site admin.

A range of types are available for use in Config.spec files:

BOOLEAN A true/false value, represented as a checkbox
COMMAND length A shell command
LANGUAGE A language (selected from {LocalesDir}
NUMBER A number
OCTAL An octal number
PASSWORD length A password (input is hidden)
PATH length A file path
PERL A perl structure, consisting of arrays and hashes
REGEX length A perl regular expression
SELECT choices Pick one of a range of choices
SELECTCLASS root Select a perl package (class)
STRING length A string
URL length A url
URLPATH length A relative URL path

All types can be followed by a comma-separated list of attributes.

EXPERT means this an expert option
M means the setting is mandatory (may not be empty)
H means the option is not visible in configure

See lib/TWiki.spec for many more examples.

Config.spec files are also used for other (non-plugin) extensions. in this case they are stored under the Contrib directory instead of the Plugins directory.

 

Maintaining Plugins

Discussions and Feedback on Plugins

Each published Plugin has a Plugin development topic on TWiki.org. Plugin development topics are named after your Plugin and end in Dev, such as MyFirstPluginDev. The Plugin development topic is a great resource to discuss feature enhancements and to get feedback from the TWiki community.

Maintaining Compatibility with Earlier TWiki Versions

The Plugin interface (TWikiFuncDotPm functions and handlers) evolve over time. TWiki 4.0 introduced new API functions to address the needs of Plugin authors. It also deprecated some functions. Some Plugins written for earlier TWiki releases using unofficial TWiki internal functions no longer work on the TWiki 4.0 codebase. All this means that some Plugins need to be updated to work on the TWiki 4.0 codebase.

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Organizations typically do not upgrade to the latest TWiki for many months. However, many administrators still would like to install the latest versions of a Plugin on their older TWiki installation. This need is fullfilled if Plugins are maintained in a compatible manner.
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Organizations typically do not upgrade to the latest TWiki for many months. However, many administrators still would like to install the latest versions of a Plugin on their older TWiki installation. This need is fulfilled if Plugins are maintained in a compatible manner.
  TIP Tip: Plugins can be written to be compatible with older and newer TWiki releases. This can be done also for Plugins using unofficial TWiki internal functions of an earlier release that no longer work on the latest TWiki codebase. TWiki:TWiki.TWikiPluginsSupplement#MaintainPlugins has more.

Handling deprecated functions

From time-to-time, the TWiki developers will add new functions to the interface (either to TWikiFuncDotPm, or new handlers). Sometimes these improvements mean that old functions have to be deprecated to keep the code manageable. When this happens, the deprecated functions will be supported in the interface for at least one more TWiki release, and probably longer, though this cannot be guaranteed.

When a plugin defines deprecated handlers, a warning will be shown in the list generated by %FAILEDPLUGINS%. Admins who see these warnings should check TWiki.org and if necessary, contact the plugin author, for an updated version of the plugin.

Updated plugins may still need to define deprecated handlers for compatibility with old TWiki versions. In this case, the plugin package that defines old handlers can suppress the warnings in %FAILEDPLUGINS%.

This is done by defining a map from the handler name to the TWiki::Plugins version in which the handler was first deprecated. For example, if we need to define the endRenderingHandler for compatibility with TWiki::Plugins versions before 1.1, we would add this to the plugin:

package TWiki::Plugins::SinkPlugin;
use vars qw( %TWikiCompatibility );
$TWikiCompatibility{endRenderingHandler} = 1.1;
If the currently-running TWiki version is 1.1 or later, then the handler will not be called and the warning will not be issued. TWiki with versions of TWiki::Plugins before 1.1 will still call the handler as required.

Related Topics: DeveloperDocumentationCategory, AdminDocumentationCategory, TWiki:TWiki.TWikiPluginsSupplement

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-- Contributors: TWiki:Main.PeterThoeny, TWiki:Main.AndreaSterbini, TWiki:MainMikeMannix, TWiki:CrawfordCurrie
 

Revision 322007-01-06 - TWikiContributor

 

TWiki Plugins

Add functionality to TWiki with readily available Plugins; create Plugins based on APIs

Overview

You can add Plugins to extend TWiki functionality, without altering the core code. A plug-in approach lets you:

  • add virtually unlimited features while keeping the main TWiki code compact and efficient;
  • heavily customize an installation and still do clean updates to new versions of TWiki;
  • rapidly develop new TWiki functions in Perl using the Plugin API.

Everything to do with TWiki Plugins - demos, new releases, downloads, development, general discussion - is available at TWiki.org, in the TWiki:Plugins web.

TWiki Plugins are developed and contributed by interested members of the community. Plugins are provided on an 'as is' basis; they are not a part of TWiki, but are independently developed and maintained.

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TIP Tip: TWiki:TWiki.TWikiPluginsSupplement on TWiki.org has supplemental documentation on TWiki Plugins.
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Relevant links on TWiki.org:
Added:
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Added:
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See other types of extensions: TWikiAddOns, TWikiContribs, TWikiSkins
 

Installing Plugins

Each TWiki Plugin comes with its own documentation: step-by-step installation instructions, a detailed description of any special requirements, version details, and a working example for testing. Many Plugins have an install script that automates these steps for you.

Special Requirements: Some Plugins need certain Perl modules to be preinstalled on the host system. Plugins may also use other resources, like graphics, other modules, applications, and templates. You should be able to find detailed instructions in the Plugin's documentation.

Each Plugin has a standard release topic, located in the TWiki:Plugins web at TWiki.org. There's usually a number of other related topics, such as a developers page, and an appraisal page.

On-Site Pretesting

The recommended approach to testing new Plugins before making them public is to create a second local TWiki installation, and test the Plugin there. You can allow selected users access to the test area. Once you are satisifed that it won't compromise your main installation, you can install it there as well.

InstalledPlugins shows which Plugins are: 1) installed, 2) loading properly, and 3) what TWiki:Codev.PluginHandlers they invoke. Any failures are shown in the Errors section. The %FAILEDPLUGINS% variable can be used to debug failures. You may also want to check your webserver error log and the various TWiki log files.

Some Notes on Plugin Performance

The performance of the system depends to some extent on the number of Plugins installed and on the Plugin implementation. Some Plugins impose no measurable performance decrease, some do. For example, a Plugin might use many Perl libraries that need to be initialized with each page view (unless you run mod_perl). You can only really tell the performance impact by installing the Plugin and by measuring the performance with and without the new Plugin. Use the TWiki:Plugins.PluginBenchmarkAddOn, or test manually with the Apache ab utility. Example on Unix:
time wget -qO /dev/null /twiki/bin/view/TWiki/AbcPlugin

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TIP If you need to install an "expensive" Plugin, and you need its functionality only in one web, you can place the Plugin topic into that web. TWiki will initialize the Plugin only if the Plugin topic is found (which won't be the case for other webs.)
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TIP If you need to install an "expensive" Plugin, but you only need its functionality only in a subset of your data, you can disable it elsewhere by defining the %DISABLEDPLUGINS% TWiki variable.
 
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Define DISABLEDPLUGINS to be a comma-separated list of names of plugins to disable. Define it in Main.TWikiPreferences to disable those plugins everywhere, in the WebPreferences topic to disable them in an individual web, or in a topic to disable them in that topic. For example,
   * Set DISABLEDPLUGINS = SpreadSheetPlugin, EditTablePlugin
 

Managing Installed Plugins

Some Plugins require additional settings or offer extra options that you have to select. Also, you may want to make a Plugin available only in certain webs, or temporarily disable it. And may want to list all available Plugins in certain topics. You can handle all of these management tasks with simple procedures:

Enabling Plugins

Plugins can be enabled and disabled with the configure script. An installed Plugin needs to be enabled before it can be used.

Plugin Evaluation Order

By default, TWiki executes Plugins in alphabetical order on Plugin name. It is possible to change the order, for example to evaluate database variables before the speadsheet CALCs. This can be done with {PluginsOrder} in the Plugins section of configure.

Plugin-Specific Settings

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Plugin-specific settings are done in individual Plugin topics. Two settings are standard for each Plugin:
  1. One line description, used to form the bullets describing the Plugins in the TextFormattingRules topic:
    • Set SHORTDESCRIPTION = Create dynamic foo bar reports
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Plugins are usually configured by variables accessible though the configure interface, but in some cases (usually older plugins) TWiki preferences are used. If a TWiki variable is defined in a Plugin topic e.g:
  • Set SETTING = Create dynamic foo bar reports
Then these settings can be retrieved as preferences variables like %<pluginname>_<var>%. For example, %RUBBERPLUGIN_SETTING% shows the value of SETTING in the RubberPlugin topic.
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  1. Debug Plugin, output can be seen in data/debug.txt. Set to 0=off or 1=on:
    • Set DEBUG = 0
  • The settings can be retrieved as Preferences variables like %<pluginname>_<var>%. For example, %DEFAULTPLUGIN_SHORTDESCRIPTION% shows the description of the DefaultPlugin.
 

Listing Active Plugins

Plugin status variables let you list all active Plugins wherever needed.

%ACTIVATEDPLUGINS%

On this TWiki site, the enabled Plugins are: SpreadSheetPlugin, BackupRestorePlugin, ColorPickerPlugin, CommentPlugin, DatePickerPlugin, EditTablePlugin, HeadlinesPlugin, InterwikiPlugin, JQueryPlugin, PreferencesPlugin, SetGetPlugin, SlideShowPlugin, SmiliesPlugin, TWikiSheetPlugin, TablePlugin, TagMePlugin, TinyMCEPlugin, TwistyPlugin, WatchlistPlugin, WysiwygPlugin.

%PLUGINDESCRIPTIONS%

  • SpreadSheetPlugin (2018-07-05, $Rev: 30478 (2018-07-16) $): Add spreadsheet calculation like "$SUM( $ABOVE() )" to TWiki tables or anywhere in topic text
  • BackupRestorePlugin (2021-03-19, $Rev: 30914 (2021-03-19) $): Administrator utility to backup, restore and upgrade a TWiki site
  • ColorPickerPlugin (2018-07-05, $Rev: 30442 (2018-07-16) $): Color picker, packaged for use in TWiki forms and TWiki applications
  • CommentPlugin (2018-07-05, $Rev: 30530 (2018-07-16) $): Quickly post comments to a page without an edit/preview/save cycle
  • DatePickerPlugin (2018-07-05, $Rev: 30446 (2018-07-16) $): Pop-up calendar with date picker, for use in TWiki forms, HTML forms and TWiki plugins
  • EditTablePlugin (2018-07-05, $Rev: 30448 (2018-07-16) $): Edit TWiki tables using edit fields, date pickers and drop down boxes
  • HeadlinesPlugin (2018-07-13, $Rev: 30560 (2018-07-16) $): Show headline news in TWiki pages based on RSS and ATOM news feeds from external sites
  • InterwikiPlugin (2018-07-05, $Rev: 30454 (2018-07-16) $): Write ExternalSite:Page to link to a page on an external site based on aliases defined in a rules topic
  • JQueryPlugin (2018-07-05, $Rev: 30456 (2018-07-16) $): jQuery JavaScript library for TWiki
  • PreferencesPlugin (2018-07-05, $Rev: 30528 (2018-07-16) $): Allows editing of preferences using fields predefined in a form
  • SetGetPlugin (2018-07-05, $Rev: 30472 (2018-07-16) $): Set and get variables and JSON objects in topics, optionally persistently across topic views
  • SlideShowPlugin (2018-07-05, $Rev: 30474 (2018-07-16) $): Create web based presentations based on topics with headings.
  • SmiliesPlugin (2018-07-05, $Rev: 30476 (2018-07-16) $): Render smilies as icons, like  :-) for smile or  :eek: for eek!
  • TWikiSheetPlugin (2018-07-15, $Rev: 30604 (2018-07-16) $): Add TWiki Sheet spreadsheet functionality to TWiki tables
  • TablePlugin (2018-07-05, $Rev: 30480 (2018-07-16) $): Control attributes of tables and sorting of table columns
  • TagMePlugin (2018-07-05, $Rev: 30482 (2018-07-16) $): Tag wiki content collectively or authoritatively to find content by keywords
  • TinyMCEPlugin (2021-06-09, $Rev: 31045 (2021-06-09) $): Integration of the Tiny MCE WYSIWYG Editor
  • TwistyPlugin (2018-07-06, $Rev: 30497 (2018-07-16) $): Twisty section JavaScript library to open/close content dynamically
  • WatchlistPlugin (2018-07-10, $Rev: 30536 (2018-07-16) $): Watch topics of interest and get notified of changes by e-mail
  • WysiwygPlugin (2018-07-06, $Rev: 30528 (2018-07-16) $): Translator framework for WYSIWYG editors

%FAILEDPLUGINS%

PluginErrors
SpreadSheetPlugin none
BackupRestorePlugin none
ColorPickerPlugin none
CommentPlugin none
DatePickerPlugin none
EditTablePlugin none
HeadlinesPlugin none
InterwikiPlugin none
JQueryPlugin none
PreferencesPlugin none
SetGetPlugin none
SlideShowPlugin none
SmiliesPlugin none
TWikiSheetPlugin none
TablePlugin none
TagMePlugin none
TinyMCEPlugin none
TwistyPlugin none
WatchlistPlugin none
WysiwygPlugin none
HandlerPlugins
afterEditHandlerWysiwygPlugin
afterRenameHandlerTagMePlugin
WatchlistPlugin
afterSaveHandlerTagMePlugin
WatchlistPlugin
beforeCommonTagsHandlerEditTablePlugin
PreferencesPlugin
TWikiSheetPlugin
TwistyPlugin
WysiwygPlugin
beforeEditHandlerTinyMCEPlugin
WysiwygPlugin
beforeMergeHandlerWysiwygPlugin
beforeSaveHandlerCommentPlugin
WatchlistPlugin
WysiwygPlugin
commonTagsHandlerSpreadSheetPlugin
BackupRestorePlugin
CommentPlugin
EditTablePlugin
JQueryPlugin
SlideShowPlugin
SmiliesPlugin
TWikiSheetPlugin
initPluginSpreadSheetPlugin
BackupRestorePlugin
ColorPickerPlugin
CommentPlugin
DatePickerPlugin
EditTablePlugin
HeadlinesPlugin
InterwikiPlugin
JQueryPlugin
PreferencesPlugin
SetGetPlugin
SlideShowPlugin
SmiliesPlugin
TWikiSheetPlugin
TablePlugin
TagMePlugin
TinyMCEPlugin
TwistyPlugin
WatchlistPlugin
WysiwygPlugin
modifyHeaderHandlerWysiwygPlugin
postRenderingHandlerPreferencesPlugin
WysiwygPlugin
preRenderingHandlerInterwikiPlugin
SmiliesPlugin
TablePlugin
20 plugins

The TWiki Plugin API

The Application Programming Interface (API) for TWiki Plugins provides the specifications for hooking into the core TWiki code from your external Perl Plugin module.

Available Core Functions

The TWikiFuncDotPm module (lib/TWiki/Func.pm) describes all the interfaces available to Plugins. Plugins should only use the interfaces described in this module.

ALERT! Note: If you use other core functions not described in Func.pm, you run the risk of creating security holes. Also, your Plugin will likely break and require updating when you upgrade to a new version of TWiki.

Predefined Hooks

In addition to TWiki core functions, Plugins can use predefined hooks, or callbacks, as described in the lib/TWiki/Plugins/EmptyPlugin.pm module.

  • All but the initPlugin are disabled. To enable a callback, remove DISABLE_ from the function name.

TWiki:Codev/StepByStepRenderingOrder helps you decide which rendering handler to use.

Hints on Writing Fast Plugins

  • Delay initialization as late as possible. For example, if your Plugin is a simple syntax processor, you might delay loading extra Perl modules until you actually see the syntax in the text.
  • For example, use an eval block like this:
    eval { require IPC::Run }
    return "<font color=\"red\">SamplePlugin: Can't load required modules ($@)</font>" if $@;
  • You can use a flag to avoid running the initialization twice
  • The TWiki:Plugins.PluginBenchmarkAddOn comes in handy to measure and fine-tune the performance of your Plugin

Plugin Version Detection

To eliminate the incompatibility problems bound to arise from active open Plugin development, a Plugin versioning system is provided for automatic compatibility checking.

  • All modules require a $VERSION='0.000' variable, beginning at 1.000.

  • The initPlugin handler should check all dependencies and return TRUE if the initialization is OK or FALSE if something went wrong.
    • The Plugin initialization code does not register a Plugin that returns FALSE (or that has no initPlugin handler).

  • $TWiki::Plugins::VERSION in the TWiki::Plugins module contains the TWiki Plugin API version, currently 6.10.
    • You can also use the %PLUGINVERSION{}% variable to query the Plugin API version or the version of installed Plugins.

Security

  • Badly written Plugins can open huge security holes in TWiki. This is especially true if care isn't taken to prevent execution of arbitrary commands on the server.
  • Don't allow sensitive configuration data to be edited by users. it is better to add sensitive configuration options to the %TWiki::cfg hash than adding it as preferences in the Plugin topic
  • Always use the TWiki::Sandbox to execute commands.
  • Always audit the Plugins you install, and make sure you are happy with the level of security provided. While every effort is made to monitor Plugin authors activities, at the end of the day they are uncontrolled user contributions.

Creating Plugins

With a reasonable knowledge of the Perl scripting language, you can create new Plugins or modify and extend existing ones. Basic plug-in architecture uses an Application Programming Interface (API), a set of software instructions that allow external code to interact with the main program. The TWiki Plugin API Plugins by providing a programming interface for TWiki.

Anatomy of a Plugin

A basic TWiki Plugin consists of two elements:

  • a Perl module, ex: MyFirstPlugin.pm
  • a documentation topic, ex: MyFirstPlugin.txt

The Perl module can be a block of code that connects with TWiki alone, or it can include other elements, like other Perl modules (including other Plugins), graphics, TWiki templates, external applications (ex: a Java applet), or just about anything else it can call. In particular, files that should be web-accessible (graphics, Java applets ...) are best placed as attachments of the MyFirstPlugin topic. Other needed Perl code is best placed in a lib/TWiki/Plugins/MyFirstPlugin/ directory.

The Plugin API handles the details of connecting your Perl module with main TWiki code. When you're familiar with the Plugin API, you're ready to develop Plugins.

Creating the Perl Module

Copy file lib/TWiki/Plugins/EmptyPlugin.pm to <name>Plugin.pm. The EmptyPlugin.pm module contains mostly empty functions, so it does nothing, but it's ready to be used. Customize it. Refer to the Plugin API specs for more information.

If your Plugin uses its own modules and objects, you must include the name of the Plugin in the package name. For example, write Package MyFirstPlugin::Attrs; instead of just Package Attrs;. Then call it using:

use TWiki::Plugins::MyFirstPlugin::Attrs;
$var = MyFirstPlugin::Attrs->new();

Measuring and Improving the Plugin Performance

A high quality Plugin performs well. You can use the TWiki:Plugins.PluginBenchmarkAddOn to measure your TWiki:Plugins.PluginBenchmarks. The data is needed as part of the Documentation Topic.

See also Hints on Writing Fast Plugins.

Writing the Documentation Topic

The Plugin documentation topic contains usage instructions and version details. It serves the Plugin files as FileAttachments for downloading. (The doc topic is also included in the distribution package.) To create a documentation topic:

  1. Copy the Plugin topic template from TWiki.org. To copy the text, go to TWiki:Plugins/PluginPackage and:
    • enter the Plugin name in the "How to Create a Plugin" section
    • click Create
    • select all in the Edit box & copy
    • Cancel the edit
    • go back to your site to the TWiki web
    • In the GoBox enter your Plugin name, for example MyFirstPlugin, press enter and create the new topic
    • paste & save new Plugin topic on your site
  2. Customize your Plugin topic.
    • Important: In case you plan to publish your Plugin on TWiki.org, use Interwiki names for author names and links to TWiki.org topics, such as TWiki:Main/TWikiGuest. This is important because links should work properly in a Plugin topic installed on any TWiki, not just on TWiki.org.
  3. Document the performance data you gathered while measuring the performance
  4. Save your topic, for use in packaging and publishing your Plugin.

OUTLINE: Doc Topic Contents
Check the Plugins web on TWiki.org for the latest Plugin doc topic template. Here's a quick overview of what's covered:

Syntax Rules: <Describe any special text formatting that will be rendered.>"

Example: <Include an example of the Plugin in action. Possibly include a static HTML version of the example to compare if the installation was a success!>"

Plugin Settings: <Description and settings for custom Plugin %VARIABLES%, and those required by TWiki.>"

  • Plugins Preferences <If user settings are needed, explain... Entering values works exactly like TWikiPreferences and WebPreferences: six (6) spaces and then:>"
    • Set <EXAMPLE = value added>

Plugin Installation Instructions: <Step-by-step set-up guide, user help, whatever it takes to install and run, goes here.>"

Plugin Info: <Version, credits, history, requirements - entered in a form, displayed as a table. Both are automatically generated when you create or edit a page in the TWiki:Plugins web.>"

Packaging for Distribution

The TWiki:Plugins.BuildContrib is a powerful build environment that is used by the TWiki project to build TWiki itself, as well as many of the Plugins. You don't have to use it, but it is highly recommended!

If you don't want (or can't) use the BuildContrib, then a minimum Plugin release consists of a Perl module with a WikiName that ends in Plugin, ex: MyFirstPlugin.pm, and a documentation page with the same name(MyFirstPlugin.txt).

  1. Distribute the Plugin files in a directory structure that mirrors TWiki. If your Plugin uses additional files, include them all:
    • lib/TWiki/Plugins/MyFirstPlugin.pm
    • data/TWiki/MyFirstPlugin.txt
    • pub/TWiki/MyFirstPlugin/uparrow.gif [a required graphic]
  2. Create a zip archive with the Plugin name (MyFirstPlugin.zip) and add the entire directory structure from Step 1. The archive should look like this:
    • lib/TWiki/Plugins/MyFirstPlugin.pm
    • data/TWiki/MyFirstPlugin.txt
    • pub/TWiki/MyFirstPlugin/uparrow.gif

Publishing for Public Use

You can release your tested, packaged Plugin to the TWiki community through the TWiki:Plugins web. All Plugins submitted to TWiki.org are available for download and further development in TWiki:Plugins/PluginPackage.

Publish your Plugin by following these steps:

  1. Post the Plugin documentation topic in the TWiki:Plugins/PluginPackage:
    • enter the Plugin name in the "How to Create a Plugin" section, for example MyFirstPlugin
    • paste in the topic text from Writing the Documentation Topic and save
  2. Attach the distribution zip file to the topic, ex: MyFirstPlugin.zip
  3. Link from the doc page to a new, blank page named after the Plugin, and ending in Dev, ex: MyFirstPluginDev. This is the discussion page for future development. (User support for Plugins is handled in TWiki:Support.)
  4. Put the Plugin into the SVN repository, see TWiki:Plugins/ReadmeFirst (optional)

NEW Once you have done the above steps once, you can use the BuildContrib to upload updates to your Plugin.

Thank you very much for sharing your Plugin with the TWiki community smile

Recommended Storage of Plugin Specific Data

Plugins sometimes need to store data. This can be Plugin internal data such as cache data, or data generated for browser consumption such as images. Plugins should store data using TWikiFuncDotPm functions that support saving and loading of topics and attachments.

Plugin Internal Data

You can create a Plugin "work area" using the TWiki::Func::getWorkArea() function, which gives you a persistant directory where you can store data files. By default they will not be web accessible. The directory is guaranteed to exist, and to be writable by the webserver user. For convenience, TWiki::Func::storeFile() and TWiki::Func::readFile() are provided to persistently store and retrieve simple data in this area.

Web Accessible Data

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Topic-specific data such as generated images can be stored in the topics attachment area, which is web accessible. Use the TWiki::Func::saveAttachment() function to store the data.
>
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Topic-specific data such as generated images can be stored in the topic's attachment area, which is web accessible. Use the TWiki::Func::saveAttachment() function to store the data.
  Recommendation for file name:
  • Prefix the filename with an underscore (the leading underscore avoids a nameclash with files attached to the same topic)
  • Identify where the attachment originated from, typically by including the Plugin name in the file name
  • Use only alphanumeric characters, underscores, dashes and periods to avoid platform dependency issues and URL issues
  • Example: _FooBarPlugin_img123.gif

Web specific data can be stored in the Plugin's attachment area, which is web accessible. Use the TWiki::Func::saveAttachment() function to store the data.

Recommendation for file names in Plugin attachment area:

  • Prefix the filename with an underscore
  • Include the name of the web in the filename
  • Use only alphanumeric characters, underscores, dashes and periods to avoid platform dependency issues and URL issues
  • Example: _Main_roundedge-ul.gif

Maintaining Plugins

Discussions and Feedback on Plugins

Each published Plugin has a Plugin development topic on TWiki.org. Plugin development topics are named after your Plugin and end in Dev, such as MyFirstPluginDev. The Plugin development topic is a great resource to discuss feature enhancements and to get feedback from the TWiki community.

Maintaining Compatibility with Earlier TWiki Versions

The Plugin interface (TWikiFuncDotPm functions and handlers) evolve over time. TWiki 4.0 introduced new API functions to address the needs of Plugin authors. It also deprecated some functions. Some Plugins written for earlier TWiki releases using unofficial TWiki internal functions no longer work on the TWiki 4.0 codebase. All this means that some Plugins need to be updated to work on the TWiki 4.0 codebase.

Organizations typically do not upgrade to the latest TWiki for many months. However, many administrators still would like to install the latest versions of a Plugin on their older TWiki installation. This need is fullfilled if Plugins are maintained in a compatible manner.

TIP Tip: Plugins can be written to be compatible with older and newer TWiki releases. This can be done also for Plugins using unofficial TWiki internal functions of an earlier release that no longer work on the latest TWiki codebase. TWiki:TWiki.TWikiPluginsSupplement#MaintainPlugins has more.

Handling deprecated functions

From time-to-time, the TWiki developers will add new functions to the interface (either to TWikiFuncDotPm, or new handlers). Sometimes these improvements mean that old functions have to be deprecated to keep the code manageable. When this happens, the deprecated functions will be supported in the interface for at least one more TWiki release, and probably longer, though this cannot be guaranteed.

When a plugin defines deprecated handlers, a warning will be shown in the list generated by %FAILEDPLUGINS%. Admins who see these warnings should check TWiki.org and if necessary, contact the plugin author, for an updated version of the plugin.

Updated plugins may still need to define deprecated handlers for compatibility with old TWiki versions. In this case, the plugin package that defines old handlers can suppress the warnings in %FAILEDPLUGINS%.

This is done by defining a map from the handler name to the TWiki::Plugins version in which the handler was first deprecated. For example, if we need to define the endRenderingHandler for compatibility with TWiki::Plugins versions before 1.1, we would add this to the plugin:

package TWiki::Plugins::SinkPlugin;
use vars qw( %TWikiCompatibility );
$TWikiCompatibility{endRenderingHandler} = 1.1;
If the currently-running TWiki version is 1.1 or later, then the handler will not be called and the warning will not be issued. TWiki with versions of TWiki::Plugins before 1.1 will still call the handler as required.

Related Topics: DeveloperDocumentationCategory, AdminDocumentationCategory, TWiki:TWiki.TWikiPluginsSupplement

-- Contributors: TWiki:Main.PeterThoeny, TWiki:Main.AndreaSterbini, TWiki:MainMikeMannix, TWiki:CrawfordCurrie

Revision 312005-03-27 - TWikiContributor

 

TWiki Plugins

Add functionality to TWiki with readily available Plugins; create Plugins based on APIs

Overview

You can add Plugins to extend TWiki functionality, without altering the core code. A plug-in approach lets you:

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  • add virtually unlimited features while keeping the main TWiki code compact and efficient;
  • heavily customize an installation and still do clean updates to new versions of TWiki;
  • rapidly develop new TWiki functions in Perl using the Plugin API.
>
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  • add virtually unlimited features while keeping the main TWiki code compact and efficient;
  • heavily customize an installation and still do clean updates to new versions of TWiki;
  • rapidly develop new TWiki functions in Perl using the Plugin API.
  Everything to do with TWiki Plugins - demos, new releases, downloads, development, general discussion - is available at TWiki.org, in the TWiki:Plugins web.

TWiki Plugins are developed and contributed by interested members of the community. Plugins are provided on an 'as is' basis; they are not a part of TWiki, but are independently developed and maintained.

TIP Tip: TWiki:TWiki.TWikiPluginsSupplement on TWiki.org has supplemental documentation on TWiki Plugins.

Installing Plugins

Each TWiki Plugin comes with its own documentation: step-by-step installation instructions, a detailed description of any special requirements, version details, and a working example for testing. Many Plugins have an install script that automates these steps for you.

Special Requirements: Some Plugins need certain Perl modules to be preinstalled on the host system. Plugins may also use other resources, like graphics, other modules, applications, and templates. You should be able to find detailed instructions in the Plugin's documentation.

Each Plugin has a standard release topic, located in the TWiki:Plugins web at TWiki.org. There's usually a number of other related topics, such as a developers page, and an appraisal page.

On-Site Pretesting

The recommended approach to testing new Plugins before making them public is to create a second local TWiki installation, and test the Plugin there. You can allow selected users access to the test area. Once you are satisifed that it won't compromise your main installation, you can install it there as well.

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InstalledPlugins shows which Plugins are: 1) installed, 2) loading properly, and 3) what TWiki:Codev.PluginHandlers they invoke. Any failures are shown in the Errors section. The %FAILEDPLUGINS% variable can be used to debug failures. You may also want to check your webserver error log and the various TWiki log files.
>
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InstalledPlugins shows which Plugins are: 1) installed, 2) loading properly, and 3) what TWiki:Codev.PluginHandlers they invoke. Any failures are shown in the Errors section. The %FAILEDPLUGINS% variable can be used to debug failures. You may also want to check your webserver error log and the various TWiki log files.
 

Some Notes on Plugin Performance

The performance of the system depends to some extent on the number of Plugins installed and on the Plugin implementation. Some Plugins impose no measurable performance decrease, some do. For example, a Plugin might use many Perl libraries that need to be initialized with each page view (unless you run mod_perl). You can only really tell the performance impact by installing the Plugin and by measuring the performance with and without the new Plugin. Use the TWiki:Plugins.PluginBenchmarkAddOn, or test manually with the Apache ab utility. Example on Unix:
time wget -qO /dev/null /twiki/bin/view/TWiki/AbcPlugin

TIP If you need to install an "expensive" Plugin, and you need its functionality only in one web, you can place the Plugin topic into that web. TWiki will initialize the Plugin only if the Plugin topic is found (which won't be the case for other webs.)

Managing Installed Plugins

Some Plugins require additional settings or offer extra options that you have to select. Also, you may want to make a Plugin available only in certain webs, or temporarily disable it. And may want to list all available Plugins in certain topics. You can handle all of these management tasks with simple procedures:

Enabling Plugins

Plugins can be enabled and disabled with the configure script. An installed Plugin needs to be enabled before it can be used.

Plugin Evaluation Order

By default, TWiki executes Plugins in alphabetical order on Plugin name. It is possible to change the order, for example to evaluate database variables before the speadsheet CALCs. This can be done with {PluginsOrder} in the Plugins section of configure.

Plugin-Specific Settings

Plugin-specific settings are done in individual Plugin topics. Two settings are standard for each Plugin:

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  1. One line description, used to form the bullets describing the Plugins in the TextFormattingRules topic:
    • Set SHORTDESCRIPTION = Create dynamic foo bar reports
  2. Debug Plugin, output can be seen in data/debug.txt. Set to 0=off or 1=on:
    • Set DEBUG = 0
  • The settings can be retrieved as Preferences variables like %<pluginname>_<var>%. For example, %DEFAULTPLUGIN_SHORTDESCRIPTION% shows the description of the DefaultPlugin.
>
>
  1. One line description, used to form the bullets describing the Plugins in the TextFormattingRules topic:
    • Set SHORTDESCRIPTION = Create dynamic foo bar reports
  2. Debug Plugin, output can be seen in data/debug.txt. Set to 0=off or 1=on:
    • Set DEBUG = 0
  • The settings can be retrieved as Preferences variables like %<pluginname>_<var>%. For example, %DEFAULTPLUGIN_SHORTDESCRIPTION% shows the description of the DefaultPlugin.
 

Listing Active Plugins

Plugin status variables let you list all active Plugins wherever needed.

%ACTIVATEDPLUGINS%

On this TWiki site, the enabled Plugins are: SpreadSheetPlugin, BackupRestorePlugin, ColorPickerPlugin, CommentPlugin, DatePickerPlugin, EditTablePlugin, HeadlinesPlugin, InterwikiPlugin, JQueryPlugin, PreferencesPlugin, SetGetPlugin, SlideShowPlugin, SmiliesPlugin, TWikiSheetPlugin, TablePlugin, TagMePlugin, TinyMCEPlugin, TwistyPlugin, WatchlistPlugin, WysiwygPlugin.

%PLUGINDESCRIPTIONS%

  • SpreadSheetPlugin (2018-07-05, $Rev: 30478 (2018-07-16) $): Add spreadsheet calculation like "$SUM( $ABOVE() )" to TWiki tables or anywhere in topic text
  • BackupRestorePlugin (2021-03-19, $Rev: 30914 (2021-03-19) $): Administrator utility to backup, restore and upgrade a TWiki site
  • ColorPickerPlugin (2018-07-05, $Rev: 30442 (2018-07-16) $): Color picker, packaged for use in TWiki forms and TWiki applications
  • CommentPlugin (2018-07-05, $Rev: 30530 (2018-07-16) $): Quickly post comments to a page without an edit/preview/save cycle
  • DatePickerPlugin (2018-07-05, $Rev: 30446 (2018-07-16) $): Pop-up calendar with date picker, for use in TWiki forms, HTML forms and TWiki plugins
  • EditTablePlugin (2018-07-05, $Rev: 30448 (2018-07-16) $): Edit TWiki tables using edit fields, date pickers and drop down boxes
  • HeadlinesPlugin (2018-07-13, $Rev: 30560 (2018-07-16) $): Show headline news in TWiki pages based on RSS and ATOM news feeds from external sites
  • InterwikiPlugin (2018-07-05, $Rev: 30454 (2018-07-16) $): Write ExternalSite:Page to link to a page on an external site based on aliases defined in a rules topic
  • JQueryPlugin (2018-07-05, $Rev: 30456 (2018-07-16) $): jQuery JavaScript library for TWiki
  • PreferencesPlugin (2018-07-05, $Rev: 30528 (2018-07-16) $): Allows editing of preferences using fields predefined in a form
  • SetGetPlugin (2018-07-05, $Rev: 30472 (2018-07-16) $): Set and get variables and JSON objects in topics, optionally persistently across topic views
  • SlideShowPlugin (2018-07-05, $Rev: 30474 (2018-07-16) $): Create web based presentations based on topics with headings.
  • SmiliesPlugin (2018-07-05, $Rev: 30476 (2018-07-16) $): Render smilies as icons, like  :-) for smile or  :eek: for eek!
  • TWikiSheetPlugin (2018-07-15, $Rev: 30604 (2018-07-16) $): Add TWiki Sheet spreadsheet functionality to TWiki tables
  • TablePlugin (2018-07-05, $Rev: 30480 (2018-07-16) $): Control attributes of tables and sorting of table columns
  • TagMePlugin (2018-07-05, $Rev: 30482 (2018-07-16) $): Tag wiki content collectively or authoritatively to find content by keywords
  • TinyMCEPlugin (2021-06-09, $Rev: 31045 (2021-06-09) $): Integration of the Tiny MCE WYSIWYG Editor
  • TwistyPlugin (2018-07-06, $Rev: 30497 (2018-07-16) $): Twisty section JavaScript library to open/close content dynamically
  • WatchlistPlugin (2018-07-10, $Rev: 30536 (2018-07-16) $): Watch topics of interest and get notified of changes by e-mail
  • WysiwygPlugin (2018-07-06, $Rev: 30528 (2018-07-16) $): Translator framework for WYSIWYG editors

%FAILEDPLUGINS%

PluginErrors
SpreadSheetPlugin none
BackupRestorePlugin none
ColorPickerPlugin none
CommentPlugin none
DatePickerPlugin none
EditTablePlugin none
HeadlinesPlugin none
InterwikiPlugin none
JQueryPlugin none
PreferencesPlugin none
SetGetPlugin none
SlideShowPlugin none
SmiliesPlugin none
TWikiSheetPlugin none
TablePlugin none
TagMePlugin none
TinyMCEPlugin none
TwistyPlugin none
WatchlistPlugin none
WysiwygPlugin none
HandlerPlugins
afterEditHandlerWysiwygPlugin
afterRenameHandlerTagMePlugin
WatchlistPlugin
afterSaveHandlerTagMePlugin
WatchlistPlugin
beforeCommonTagsHandlerEditTablePlugin
PreferencesPlugin
TWikiSheetPlugin
TwistyPlugin
WysiwygPlugin
beforeEditHandlerTinyMCEPlugin
WysiwygPlugin
beforeMergeHandlerWysiwygPlugin
beforeSaveHandlerCommentPlugin
WatchlistPlugin
WysiwygPlugin
commonTagsHandlerSpreadSheetPlugin
BackupRestorePlugin
CommentPlugin
EditTablePlugin
JQueryPlugin
SlideShowPlugin
SmiliesPlugin
TWikiSheetPlugin
initPluginSpreadSheetPlugin
BackupRestorePlugin
ColorPickerPlugin
CommentPlugin
DatePickerPlugin
EditTablePlugin
HeadlinesPlugin
InterwikiPlugin
JQueryPlugin
PreferencesPlugin
SetGetPlugin
SlideShowPlugin
SmiliesPlugin
TWikiSheetPlugin
TablePlugin
TagMePlugin
TinyMCEPlugin
TwistyPlugin
WatchlistPlugin
WysiwygPlugin
modifyHeaderHandlerWysiwygPlugin
postRenderingHandlerPreferencesPlugin
WysiwygPlugin
preRenderingHandlerInterwikiPlugin
SmiliesPlugin
TablePlugin
20 plugins

The TWiki Plugin API

The Application Programming Interface (API) for TWiki Plugins provides the specifications for hooking into the core TWiki code from your external Perl Plugin module.

Available Core Functions

The TWikiFuncDotPm module (lib/TWiki/Func.pm) describes all the interfaces available to Plugins. Plugins should only use the interfaces described in this module.

ALERT! Note: If you use other core functions not described in Func.pm, you run the risk of creating security holes. Also, your Plugin will likely break and require updating when you upgrade to a new version of TWiki.

Predefined Hooks

In addition to TWiki core functions, Plugins can use predefined hooks, or callbacks, as described in the lib/TWiki/Plugins/EmptyPlugin.pm module.

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  • All but the initPlugin are disabled. To enable a callback, remove DISABLE_ from the function name.
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  • All but the initPlugin are disabled. To enable a callback, remove DISABLE_ from the function name.
  TWiki:Codev/StepByStepRenderingOrder helps you decide which rendering handler to use.

Hints on Writing Fast Plugins

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  • Delay initialization as late as possible. For example, if your Plugin is a simple syntax processor, you might delay loading extra Perl modules until you actually see the syntax in the text.
  • For example, use an eval block like this:
    eval { require IPC::Run }
    return "<font color=\"red\">SamplePlugin: Can't load required modules ($@)</font>" if $@;
  • You can use a flag to avoid running the initialization twice
  • The TWiki:Plugins.PluginBenchmarkAddOn comes in handy to measure and fine-tune the performance of your Plugin
>
>
  • Delay initialization as late as possible. For example, if your Plugin is a simple syntax processor, you might delay loading extra Perl modules until you actually see the syntax in the text.
  • For example, use an eval block like this:
    eval { require IPC::Run }
    return "<font color=\"red\">SamplePlugin: Can't load required modules ($@)</font>" if $@;
  • You can use a flag to avoid running the initialization twice
  • The TWiki:Plugins.PluginBenchmarkAddOn comes in handy to measure and fine-tune the performance of your Plugin
 

Plugin Version Detection

To eliminate the incompatibility problems bound to arise from active open Plugin development, a Plugin versioning system is provided for automatic compatibility checking.

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  • All modules require a $VERSION='0.000' variable, beginning at 1.000.
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  • All modules require a $VERSION='0.000' variable, beginning at 1.000.
 
Changed:
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  • The initPlugin handler should check all dependencies and return TRUE if the initialization is OK or FALSE if something went wrong.
    • The Plugin initialization code does not register a Plugin that returns FALSE (or that has no initPlugin handler).
>
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  • The initPlugin handler should check all dependencies and return TRUE if the initialization is OK or FALSE if something went wrong.
    • The Plugin initialization code does not register a Plugin that returns FALSE (or that has no initPlugin handler).
 
Changed:
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  • $TWiki::Plugins::VERSION in the TWiki::Plugins module contains the TWiki Plugin API version, currently 6.10.
    • You can also use the %PLUGINVERSION{}% variable to query the Plugin API version or the version of installed Plugins.
>
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  • $TWiki::Plugins::VERSION in the TWiki::Plugins module contains the TWiki Plugin API version, currently 6.10.
    • You can also use the %PLUGINVERSION{}% variable to query the Plugin API version or the version of installed Plugins.
 

Security

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  • Badly written Plugins can open huge security holes in TWiki. This is especially true if care isn't taken to prevent execution of arbitrary commands on the server.
  • Don't allow sensitive configuration data to be edited by users. it is better to add sensitive configuration options to the %TWiki::cfg hash than adding it as preferences in the Plugin topic
  • Always use the TWiki::Sandbox to execute commands.
  • Always audit the Plugins you install, and make sure you are happy with the level of security provided. While every effort is made to monitor Plugin authors activities, at the end of the day they are uncontrolled user contributions.
>
>
  • Badly written Plugins can open huge security holes in TWiki. This is especially true if care isn't taken to prevent execution of arbitrary commands on the server.
  • Don't allow sensitive configuration data to be edited by users. it is better to add sensitive configuration options to the %TWiki::cfg hash than adding it as preferences in the Plugin topic
  • Always use the TWiki::Sandbox to execute commands.
  • Always audit the Plugins you install, and make sure you are happy with the level of security provided. While every effort is made to monitor Plugin authors activities, at the end of the day they are uncontrolled user contributions.
 

Creating Plugins

With a reasonable knowledge of the Perl scripting language, you can create new Plugins or modify and extend existing ones. Basic plug-in architecture uses an Application Programming Interface (API), a set of software instructions that allow external code to interact with the main program. The TWiki Plugin API Plugins by providing a programming interface for TWiki.

Anatomy of a Plugin

A basic TWiki Plugin consists of two elements:

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  • a Perl module, ex: MyFirstPlugin.pm
  • a documentation topic, ex: MyFirstPlugin.txt
>
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  • a Perl module, ex: MyFirstPlugin.pm
  • a documentation topic, ex: MyFirstPlugin.txt
  The Perl module can be a block of code that connects with TWiki alone, or it can include other elements, like other Perl modules (including other Plugins), graphics, TWiki templates, external applications (ex: a Java applet), or just about anything else it can call. In particular, files that should be web-accessible (graphics, Java applets ...) are best placed as attachments of the MyFirstPlugin topic. Other needed Perl code is best placed in a lib/TWiki/Plugins/MyFirstPlugin/ directory.

The Plugin API handles the details of connecting your Perl module with main TWiki code. When you're familiar with the Plugin API, you're ready to develop Plugins.

Creating the Perl Module

Copy file lib/TWiki/Plugins/EmptyPlugin.pm to <name>Plugin.pm. The EmptyPlugin.pm module contains mostly empty functions, so it does nothing, but it's ready to be used. Customize it. Refer to the Plugin API specs for more information.

If your Plugin uses its own modules and objects, you must include the name of the Plugin in the package name. For example, write Package MyFirstPlugin::Attrs; instead of just Package Attrs;. Then call it using:

use TWiki::Plugins::MyFirstPlugin::Attrs;
$var = MyFirstPlugin::Attrs->new();

Measuring and Improving the Plugin Performance

A high quality Plugin performs well. You can use the TWiki:Plugins.PluginBenchmarkAddOn to measure your TWiki:Plugins.PluginBenchmarks. The data is needed as part of the Documentation Topic.

See also Hints on Writing Fast Plugins.

Writing the Documentation Topic

The Plugin documentation topic contains usage instructions and version details. It serves the Plugin files as FileAttachments for downloading. (The doc topic is also included in the distribution package.) To create a documentation topic:

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  1. Copy the Plugin topic template from TWiki.org. To copy the text, go to TWiki:Plugins/PluginPackage and:
    • enter the Plugin name in the "How to Create a Plugin" section
    • click Create
    • select all in the Edit box & copy
    • Cancel the edit
    • go back to your site to the TWiki web
    • In the GoBox enter your Plugin name, for example MyFirstPlugin, press enter and create the new topic
    • paste & save new Plugin topic on your site
  2. Customize your Plugin topic.
    • Important: In case you plan to publish your Plugin on TWiki.org, use Interwiki names for author names and links to TWiki.org topics, such as TWiki:Main/TWikiGuest. This is important because links should work properly in a Plugin topic installed on any TWiki, not just on TWiki.org.
  3. Document the performance data you gathered while measuring the performance
  4. Save your topic, for use in packaging and publishing your Plugin.
>
>
  1. Copy the Plugin topic template from TWiki.org. To copy the text, go to TWiki:Plugins/PluginPackage and:
    • enter the Plugin name in the "How to Create a Plugin" section
    • click Create
    • select all in the Edit box & copy
    • Cancel the edit
    • go back to your site to the TWiki web
    • In the GoBox enter your Plugin name, for example MyFirstPlugin, press enter and create the new topic
    • paste & save new Plugin topic on your site
  2. Customize your Plugin topic.
    • Important: In case you plan to publish your Plugin on TWiki.org, use Interwiki names for author names and links to TWiki.org topics, such as TWiki:Main/TWikiGuest. This is important because links should work properly in a Plugin topic installed on any TWiki, not just on TWiki.org.
  3. Document the performance data you gathered while measuring the performance
  4. Save your topic, for use in packaging and publishing your Plugin.
 
OUTLINE: Doc Topic Contents
Check the Plugins web on TWiki.org for the latest Plugin doc topic template. Here's a quick overview of what's covered:

Syntax Rules: <Describe any special text formatting that will be rendered.>"

Example: <Include an example of the Plugin in action. Possibly include a static HTML version of the example to compare if the installation was a success!>"

Plugin Settings: <Description and settings for custom Plugin %VARIABLES%, and those required by TWiki.>"

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  • Plugins Preferences <If user settings are needed, explain... Entering values works exactly like TWikiPreferences and WebPreferences: six (6) spaces and then:>"
    • Set <EXAMPLE = value added>
>
>
  • Plugins Preferences <If user settings are needed, explain... Entering values works exactly like TWikiPreferences and WebPreferences: six (6) spaces and then:>"
    • Set <EXAMPLE = value added>
  Plugin Installation Instructions: <Step-by-step set-up guide, user help, whatever it takes to install and run, goes here.>"

Plugin Info: <Version, credits, history, requirements - entered in a form, displayed as a table. Both are automatically generated when you create or edit a page in the TWiki:Plugins web.>"

Packaging for Distribution

The TWiki:Plugins.BuildContrib is a powerful build environment that is used by the TWiki project to build TWiki itself, as well as many of the Plugins. You don't have to use it, but it is highly recommended!

If you don't want (or can't) use the BuildContrib, then a minimum Plugin release consists of a Perl module with a WikiName that ends in Plugin, ex: MyFirstPlugin.pm, and a documentation page with the same name(MyFirstPlugin.txt).

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  1. Distribute the Plugin files in a directory structure that mirrors TWiki. If your Plugin uses additional files, include them all:
    • lib/TWiki/Plugins/MyFirstPlugin.pm
    • data/TWiki/MyFirstPlugin.txt
    • pub/TWiki/MyFirstPlugin/uparrow.gif [a required graphic]
  2. Create a zip archive with the Plugin name (MyFirstPlugin.zip) and add the entire directory structure from Step 1. The archive should look like this:
    • lib/TWiki/Plugins/MyFirstPlugin.pm
    • data/TWiki/MyFirstPlugin.txt
    • pub/TWiki/MyFirstPlugin/uparrow.gif
>
>
  1. Distribute the Plugin files in a directory structure that mirrors TWiki. If your Plugin uses additional files, include them all:
    • lib/TWiki/Plugins/MyFirstPlugin.pm
    • data/TWiki/MyFirstPlugin.txt
    • pub/TWiki/MyFirstPlugin/uparrow.gif [a required graphic]
  2. Create a zip archive with the Plugin name (MyFirstPlugin.zip) and add the entire directory structure from Step 1. The archive should look like this:
    • lib/TWiki/Plugins/MyFirstPlugin.pm
    • data/TWiki/MyFirstPlugin.txt
    • pub/TWiki/MyFirstPlugin/uparrow.gif
 

Publishing for Public Use

You can release your tested, packaged Plugin to the TWiki community through the TWiki:Plugins web. All Plugins submitted to TWiki.org are available for download and further development in TWiki:Plugins/PluginPackage.

Publish your Plugin by following these steps:

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  1. Post the Plugin documentation topic in the TWiki:Plugins/PluginPackage:
    • enter the Plugin name in the "How to Create a Plugin" section, for example MyFirstPlugin
    • paste in the topic text from Writing the Documentation Topic and save
  2. Attach the distribution zip file to the topic, ex: MyFirstPlugin.zip
  3. Link from the doc page to a new, blank page named after the Plugin, and ending in Dev, ex: MyFirstPluginDev. This is the discussion page for future development. (User support for Plugins is handled in TWiki:Support.)
  4. Put the Plugin into the SVN repository, see TWiki:Plugins/ReadmeFirst (optional)
>
>
  1. Post the Plugin documentation topic in the TWiki:Plugins/PluginPackage:
    • enter the Plugin name in the "How to Create a Plugin" section, for example MyFirstPlugin
    • paste in the topic text from Writing the Documentation Topic and save
  2. Attach the distribution zip file to the topic, ex: MyFirstPlugin.zip
  3. Link from the doc page to a new, blank page named after the Plugin, and ending in Dev, ex: MyFirstPluginDev. This is the discussion page for future development. (User support for Plugins is handled in TWiki:Support.)
  4. Put the Plugin into the SVN repository, see TWiki:Plugins/ReadmeFirst (optional)
  NEW Once you have done the above steps once, you can use the BuildContrib to upload updates to your Plugin.

Thank you very much for sharing your Plugin with the TWiki community smile

Recommended Storage of Plugin Specific Data

Plugins sometimes need to store data. This can be Plugin internal data such as cache data, or data generated for browser consumption such as images. Plugins should store data using TWikiFuncDotPm functions that support saving and loading of topics and attachments.

Plugin Internal Data

You can create a Plugin "work area" using the TWiki::Func::getWorkArea() function, which gives you a persistant directory where you can store data files. By default they will not be web accessible. The directory is guaranteed to exist, and to be writable by the webserver user. For convenience, TWiki::Func::storeFile() and TWiki::Func::readFile() are provided to persistently store and retrieve simple data in this area.

Web Accessible Data

Topic-specific data such as generated images can be stored in the topics attachment area, which is web accessible. Use the TWiki::Func::saveAttachment() function to store the data.

Recommendation for file name:

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  • Prefix the filename with an underscore (the leading underscore avoids a nameclash with files attached to the same topic)
  • Identify where the attachment originated from, typically by including the Plugin name in the file name
  • Use only alphanumeric characters, underscores, dashes and periods to avoid platform dependency issues and URL issues
  • Example: _FooBarPlugin_img123.gif
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  • Prefix the filename with an underscore (the leading underscore avoids a nameclash with files attached to the same topic)
  • Identify where the attachment originated from, typically by including the Plugin name in the file name
  • Use only alphanumeric characters, underscores, dashes and periods to avoid platform dependency issues and URL issues
  • Example: _FooBarPlugin_img123.gif
  Web specific data can be stored in the Plugin's attachment area, which is web accessible. Use the TWiki::Func::saveAttachment() function to store the data.

Recommendation for file names in Plugin attachment area:

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  • Prefix the filename with an underscore
  • Include the name of the web in the filename
  • Use only alphanumeric characters, underscores, dashes and periods to avoid platform dependency issues and URL issues
  • Example: _Main_roundedge-ul.gif
>
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  • Prefix the filename with an underscore
  • Include the name of the web in the filename
  • Use only alphanumeric characters, underscores, dashes and periods to avoid platform dependency issues and URL issues
  • Example: _Main_roundedge-ul.gif
 

Maintaining Plugins

Discussions and Feedback on Plugins

Each published Plugin has a Plugin development topic on TWiki.org. Plugin development topics are named after your Plugin and end in Dev, such as MyFirstPluginDev. The Plugin development topic is a great resource to discuss feature enhancements and to get feedback from the TWiki community.

Maintaining Compatibility with Earlier TWiki Versions

The Plugin interface (TWikiFuncDotPm functions and handlers) evolve over time. TWiki 4.0 introduced new API functions to address the needs of Plugin authors. It also deprecated some functions. Some Plugins written for earlier TWiki releases using unofficial TWiki internal functions no longer work on the TWiki 4.0 codebase. All this means that some Plugins need to be updated to work on the TWiki 4.0 codebase.

Organizations typically do not upgrade to the latest TWiki for many months. However, many administrators still would like to install the latest versions of a Plugin on their older TWiki installation. This need is fullfilled if Plugins are maintained in a compatible manner.

TIP Tip: Plugins can be written to be compatible with older and newer TWiki releases. This can be done also for Plugins using unofficial TWiki internal functions of an earlier release that no longer work on the latest TWiki codebase. TWiki:TWiki.TWikiPluginsSupplement#MaintainPlugins has more.

Handling deprecated functions

From time-to-time, the TWiki developers will add new functions to the interface (either to TWikiFuncDotPm, or new handlers). Sometimes these improvements mean that old functions have to be deprecated to keep the code manageable. When this happens, the deprecated functions will be supported in the interface for at least one more TWiki release, and probably longer, though this cannot be guaranteed.

When a plugin defines deprecated handlers, a warning will be shown in the list generated by %FAILEDPLUGINS%. Admins who see these warnings should check TWiki.org and if necessary, contact the plugin author, for an updated version of the plugin.

Updated plugins may still need to define deprecated handlers for compatibility with old TWiki versions. In this case, the plugin package that defines old handlers can suppress the warnings in %FAILEDPLUGINS%.

This is done by defining a map from the handler name to the TWiki::Plugins version in which the handler was first deprecated. For example, if we need to define the endRenderingHandler for compatibility with TWiki::Plugins versions before 1.1, we would add this to the plugin:

package TWiki::Plugins::SinkPlugin;
use vars qw( %TWikiCompatibility );
$TWikiCompatibility{endRenderingHandler} = 1.1;
If the currently-running TWiki version is 1.1 or later, then the handler will not be called and the warning will not be issued. TWiki with versions of TWiki::Plugins before 1.1 will still call the handler as required.

Related Topics: DeveloperDocumentationCategory, AdminDocumentationCategory, TWiki:TWiki.TWikiPluginsSupplement

-- Contributors: TWiki:Main.PeterThoeny, TWiki:Main.AndreaSterbini, TWiki:MainMikeMannix, TWiki:CrawfordCurrie

Revision 302005-03-27 - TWikiContributor

 

TWiki Plugins

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Plug-in enhanced feature add-ons, with a Plugin API for developers
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Add functionality to TWiki with readily available Plugins; create Plugins based on APIs
 

Overview

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You can add Plugins to extend TWiki's functionality, without altering the core program code. A plug-in approach lets you:
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You can add Plugins to extend TWiki functionality, without altering the core code. A plug-in approach lets you:
 
  • add virtually unlimited features while keeping the main TWiki code compact and efficient;
  • heavily customize an installation and still do clean updates to new versions of TWiki;
  • rapidly develop new TWiki functions in Perl using the Plugin API.

Everything to do with TWiki Plugins - demos, new releases, downloads, development, general discussion - is available at TWiki.org, in the TWiki:Plugins web.

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Preinstalled Plugins

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TWiki Plugins are developed and contributed by interested members of the community. Plugins are provided on an 'as is' basis; they are not a part of TWiki, but are independently developed and maintained.
 
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TWiki comes with a set of Plugins as part of the standard installation.
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TIP Tip: TWiki:TWiki.TWikiPluginsSupplement on TWiki.org has supplemental documentation on TWiki Plugins.
 
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  • DefaultPlugin: Optionally handles some legacy variables from older versions of TWiki. You can control this option from TWikiPreferences. (Perl programmers can also add rules for simple custom processing.)
  • EmptyPlugin: Is a fully functional module, minus active code; it does nothing and serves as a template for new Plugin development
  • CommentPlugin: %COMMENTPLUGIN_SHORTDESCRIPTION%
  • InterwikiPlugin: Use it for shorthand linking to remote sites, ex: TWiki:Plugins expands to TWiki:Plugins on TWiki.org. You can edit the predefined set of of Wiki-related sites, and add your own
  • EditTablePlugin: Edit TWiki tables using edit fields, date pickers and drop down boxes
  • RenderListPlugin: %RENDERLISTPLUGIN_SHORTDESCRIPTION%
  • SlideShowPlugin: Create web based presentations based on topics with headings.
  • SmiliesPlugin: Render smilies as icons, like  :-) for smile or  :eek: for eek!
  • SpreadSheetPlugin: Add spreadsheet calculation like "$SUM( $ABOVE() )" to TWiki tables or anywhere in topic text
  • TablePlugin: Control attributes of tables and sorting of table columns
 

Installing Plugins

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Each TWikiPlugin comes with full documentation: step-by-step installation instructions, a detailed description of any special requirements, version details, and a working example for testing.
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Each TWiki Plugin comes with its own documentation: step-by-step installation instructions, a detailed description of any special requirements, version details, and a working example for testing. Many Plugins have an install script that automates these steps for you.
 
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Most Plugins can be installed in three easy steps, with no programming skills required:
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Special Requirements: Some Plugins need certain Perl modules to be preinstalled on the host system. Plugins may also use other resources, like graphics, other modules, applications, and templates. You should be able to find detailed instructions in the Plugin's documentation.
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  1. Download the zip file containing the Plugin, documentation, and any other required files, from TWiki:Plugins.
  2. Distribute the files to their proper locations - unzip the zip archive in your TWiki installation directory - if have a standard TWiki installation, this will distribute automatically. Otherwise, place the files according to the directory paths listed on the Plugin top in TWiki:Plugins.
  3. Check the demo example on the Plugin topic: if it's working, the installation was fine!
 
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Special Requests: Some Plugins need certain Perl modules to be preinstalled on the host system. Plugins may also use other resources, like graphics, other modules, applications, templates. In these cases, detailed instructions are in the Plugin documentation.
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Each Plugin has a standard release topic, located in the TWiki:Plugins web at TWiki.org. There's usually a number of other related topics, such as a developers page, and an appraisal page.
 
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Each Plugin has a standard release page, located in the TWiki:Plugins web at TWiki.org. In addition to the documentation topic (SomePlugin), there's a separate development page.
  • Doc page: Read all available info about the Plugin; download the attached distribution files.
  • Dev page: Post feature requests, bug reports and general dev comments; topic title ends in Dev (SomePluginDev).
  • User support: Post installation, how to use type questions (and answers, if you have them) in the TWiki:Support web.
 

On-Site Pretesting

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To test new Plugins on your installation before making them public, you may want to use one of these two approaches:
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The recommended approach to testing new Plugins before making them public is to create a second local TWiki installation, and test the Plugin there. You can allow selected users access to the test area. Once you are satisifed that it won't compromise your main installation, you can install it there as well.
 
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  • Method 1: Safely test on-the-fly by creating separate Production and Test branches in your live TWiki installation.
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InstalledPlugins shows which Plugins are: 1) installed, 2) loading properly, and 3) what TWiki:Codev.PluginHandlers they invoke. Any failures are shown in the Errors section. The %FAILEDPLUGINS% variable can be used to debug failures. You may also want to check your webserver error log and the various TWiki log files.
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    • Duplicate the twiki/bin and twiki/lib directories for the Test version, and adjust the paths in the new lib/TWiki.cfg. The following directories are shared: twiki/data, twiki/templates and twiki/pub.
    • Test Plugins and other new features in the Test installation until you're satisfied.
      • ALERT! If you modify topics using the new features, live users will likely see unfamiliar new META tags showing up on their pages - to avoid this, create and edit test-only topics to try out new features.
    • Copy the modified files to the Production installation. You can update a TWiki installation live and users won't even notice.
 
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  • Method 2: List the Plugin being tested in the DISABLEDPLUGINS variable in TWikiPreferences. Redefine the DISABLEDPLUGINS variable in the Sandbox web and do the testing there.
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Some Notes on Plugin Performance

 
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Checking that Plugins are Working on a Live Server

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The performance of the system depends to some extent on the number of Plugins installed and on the Plugin implementation. Some Plugins impose no measurable performance decrease, some do. For example, a Plugin might use many Perl libraries that need to be initialized with each page view (unless you run mod_perl). You can only really tell the performance impact by installing the Plugin and by measuring the performance with and without the new Plugin. Use the TWiki:Plugins.PluginBenchmarkAddOn, or test manually with the Apache ab utility. Example on Unix:
time wget -qO /dev/null /twiki/bin/view/TWiki/AbcPlugin
 
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InstalledPlugins shows which Plugins are: 1) installed, 2) loading properly and 3) what TWiki:Codev.PluginHandlers they invoke. Any failures are shown in the Errors section.
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TIP If you need to install an "expensive" Plugin, and you need its functionality only in one web, you can place the Plugin topic into that web. TWiki will initialize the Plugin only if the Plugin topic is found (which won't be the case for other webs.)
 
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A Note on Plugin Performance

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Added:
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Managing Installed Plugins

 
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The performance of the system depends on the number of Plugins installed and on the Plugin implementation. Some Plugins impose no measurable performance decrease, some do. For example, outsidePREHandler is an expensive callback function, or a Plugin might use many Perl libraries that need to be initialized with each page view (unless you run mod_perl). It is recommended to measure the performance with and without a new Plugin. Example for Unix:
time wget -qO /dev/null https://wiki.ivoa.net/twiki/bin/view/TWiki/AbcPlugin
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Some Plugins require additional settings or offer extra options that you have to select. Also, you may want to make a Plugin available only in certain webs, or temporarily disable it. And may want to list all available Plugins in certain topics. You can handle all of these management tasks with simple procedures:
 
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In case you need to install an "expensive" Plugin and you need its functionality only in one web you can place the Plugin topic into that web. TWiki will initialize the Plugin only if the Plugin topic is found (which won't be the case for other webs.)
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Enabling Plugins

 
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Managing Plugins

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Plugins can be enabled and disabled with the configure script. An installed Plugin needs to be enabled before it can be used.
 
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When you finish installing a Plugin, you should be able to read the user instructions and go. In fact, some Plugins require additional settings or offer extra options that you have to select. Also, you may want to make a Plugin available only in certain webs, or temporarily disable it. And may want to list all available Plugins in certain topics. You can handle all of these management tasks with simple procedures.
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Plugin Evaluation Order

 
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Setting Preferences

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By default, TWiki executes Plugins in alphabetical order on Plugin name. It is possible to change the order, for example to evaluate database variables before the speadsheet CALCs. This can be done with {PluginsOrder} in the Plugins section of configure.
 
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Installed Plugins can be toggled on or off, site-wide or by web, through TWikiPreferences and individual WebPreferences:
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Plugin-Specific Settings

 
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  • All Plugin modules present in the lib/TWiki/Plugins directory are activated automatically unless disabled by the DISABLEDPLUGINS Preferences variable in TWikiPreferences. You can optionally list the installed Plugins in the INSTALLEDPLUGINS Preferences variable. This is useful to define the sequence of Plugin execution, or to specify other webs than the TWiki web for the Plugin topics. Settings in TWikiPreferences are:
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Plugin-specific settings are done in individual Plugin topics. Two settings are standard for each Plugin:
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    • Set INSTALLEDPLUGINS = DefaultPlugin, ...
    • Set DISABLEDPLUGINS = EmptyPlugin, ...

Plugin execution order in TWiki is determined by searching Plugin topics in a specific sequence: First, full web.topicname name, if specified in INSTALLEDPLUGINS; next, the TWiki web is searched; and finally, the current web.

Plugin-specific settings are done in individual Plugin topics. Two settings are standard for each Plugin:

 
  1. One line description, used to form the bullets describing the Plugins in the TextFormattingRules topic:
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    • Set SHORTDESCRIPTION = Blah blah woof woof.
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    • Set SHORTDESCRIPTION = Create dynamic foo bar reports
 
  1. Debug Plugin, output can be seen in data/debug.txt. Set to 0=off or 1=on:
    • Set DEBUG = 0
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  • The settings can be retrieved as Preferences variables like %<pluginname>_<var>%, ex: %DEFAULTPLUGIN_SHORTDESCRIPTION% shows the description of the DefaultPlugin.
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  • The settings can be retrieved as Preferences variables like %<pluginname>_<var>%. For example, %DEFAULTPLUGIN_SHORTDESCRIPTION% shows the description of the DefaultPlugin.
 

Listing Active Plugins

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Plugin status variables let you list all active Plugins wherever needed. There are two list formats:
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Plugin status variables let you list all active Plugins wherever needed.
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  • The %ACTIVATEDPLUGINS% variable lists activated Plugins by name. (This variable is displayed in TWikiPreferences for debugging use.)
  • The %PLUGINDESCRIPTIONS% variable displays a bullet list with a one-line description of each active Plugins. This variable is based on the %<plugin>_SHORTDESCRIPTION% Preferences variables of individual topics and is shown in TextFormattingRules.
 
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DEMO: Automatically List Active Plugins Using Variables
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%ACTIVATEDPLUGINS%

On this TWiki site, the enabled Plugins are: SpreadSheetPlugin, BackupRestorePlugin, ColorPickerPlugin, CommentPlugin, DatePickerPlugin, EditTablePlugin, HeadlinesPlugin, InterwikiPlugin, JQueryPlugin, PreferencesPlugin, SetGetPlugin, SlideShowPlugin, SmiliesPlugin, TWikiSheetPlugin, TablePlugin, TagMePlugin, TinyMCEPlugin, TwistyPlugin, WatchlistPlugin, WysiwygPlugin.
 
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Using %ACTIVATEDPLUGINS%:
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%PLUGINDESCRIPTIONS%

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On this TWiki site, the active Plugins are: SpreadSheetPlugin, BackupRestorePlugin, ColorPickerPlugin, CommentPlugin, DatePickerPlugin, EditTablePlugin, HeadlinesPlugin, InterwikiPlugin, JQueryPlugin, PreferencesPlugin, SetGetPlugin, SlideShowPlugin, SmiliesPlugin, TWikiSheetPlugin, TablePlugin, TagMePlugin, TinyMCEPlugin, TwistyPlugin, WatchlistPlugin, WysiwygPlugin.

Using %PLUGINDESCRIPTIONS%:
You can use any of these active TWiki Plugins:

 
  • SpreadSheetPlugin (2018-07-05, $Rev: 30478 (2018-07-16) $): Add spreadsheet calculation like "$SUM( $ABOVE() )" to TWiki tables or anywhere in topic text
  • BackupRestorePlugin (2021-03-19, $Rev: 30914 (2021-03-19) $): Administrator utility to backup, restore and upgrade a TWiki site
  • ColorPickerPlugin (2018-07-05, $Rev: 30442 (2018-07-16) $): Color picker, packaged for use in TWiki forms and TWiki applications
  • CommentPlugin (2018-07-05, $Rev: 30530 (2018-07-16) $): Quickly post comments to a page without an edit/preview/save cycle
  • DatePickerPlugin (2018-07-05, $Rev: 30446 (2018-07-16) $): Pop-up calendar with date picker, for use in TWiki forms, HTML forms and TWiki plugins
  • EditTablePlugin (2018-07-05, $Rev: 30448 (2018-07-16) $): Edit TWiki tables using edit fields, date pickers and drop down boxes
  • HeadlinesPlugin (2018-07-13, $Rev: 30560 (2018-07-16) $): Show headline news in TWiki pages based on RSS and ATOM news feeds from external sites
  • InterwikiPlugin (2018-07-05, $Rev: 30454 (2018-07-16) $): Write ExternalSite:Page to link to a page on an external site based on aliases defined in a rules topic
  • JQueryPlugin (2018-07-05, $Rev: 30456 (2018-07-16) $): jQuery JavaScript library for TWiki
  • PreferencesPlugin (2018-07-05, $Rev: 30528 (2018-07-16) $): Allows editing of preferences using fields predefined in a form
  • SetGetPlugin (2018-07-05, $Rev: 30472 (2018-07-16) $): Set and get variables and JSON objects in topics, optionally persistently across topic views
  • SlideShowPlugin (2018-07-05, $Rev: 30474 (2018-07-16) $): Create web based presentations based on topics with headings.
  • SmiliesPlugin (2018-07-05, $Rev: 30476 (2018-07-16) $): Render smilies as icons, like  :-) for smile or  :eek: for eek!
  • TWikiSheetPlugin (2018-07-15, $Rev: 30604 (2018-07-16) $): Add TWiki Sheet spreadsheet functionality to TWiki tables
  • TablePlugin (2018-07-05, $Rev: 30480 (2018-07-16) $): Control attributes of tables and sorting of table columns
  • TagMePlugin (2018-07-05, $Rev: 30482 (2018-07-16) $): Tag wiki content collectively or authoritatively to find content by keywords
  • TinyMCEPlugin (2021-06-09, $Rev: 31045 (2021-06-09) $): Integration of the Tiny MCE WYSIWYG Editor
  • TwistyPlugin (2018-07-06, $Rev: 30497 (2018-07-16) $): Twisty section JavaScript library to open/close content dynamically
  • WatchlistPlugin (2018-07-10, $Rev: 30536 (2018-07-16) $): Watch topics of interest and get notified of changes by e-mail
  • WysiwygPlugin (2018-07-06, $Rev: 30528 (2018-07-16) $): Translator framework for WYSIWYG editors
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Added:
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%FAILEDPLUGINS%

PluginErrors
SpreadSheetPlugin none
BackupRestorePlugin none
ColorPickerPlugin none
CommentPlugin none
DatePickerPlugin none
EditTablePlugin none
HeadlinesPlugin none
InterwikiPlugin none
JQueryPlugin none
PreferencesPlugin none
SetGetPlugin none
SlideShowPlugin none
SmiliesPlugin none
TWikiSheetPlugin none
TablePlugin none
TagMePlugin none
TinyMCEPlugin none
TwistyPlugin none
WatchlistPlugin none
WysiwygPlugin none
HandlerPlugins
afterEditHandlerWysiwygPlugin
afterRenameHandlerTagMePlugin
WatchlistPlugin
afterSaveHandlerTagMePlugin
WatchlistPlugin
beforeCommonTagsHandlerEditTablePlugin
PreferencesPlugin
TWikiSheetPlugin
TwistyPlugin
WysiwygPlugin
beforeEditHandlerTinyMCEPlugin
WysiwygPlugin
beforeMergeHandlerWysiwygPlugin
beforeSaveHandlerCommentPlugin
WatchlistPlugin
WysiwygPlugin
commonTagsHandlerSpreadSheetPlugin
BackupRestorePlugin
CommentPlugin
EditTablePlugin
JQueryPlugin
SlideShowPlugin
SmiliesPlugin
TWikiSheetPlugin
initPluginSpreadSheetPlugin
BackupRestorePlugin
ColorPickerPlugin
CommentPlugin
DatePickerPlugin
EditTablePlugin
HeadlinesPlugin
InterwikiPlugin
JQueryPlugin
PreferencesPlugin
SetGetPlugin
SlideShowPlugin
SmiliesPlugin
TWikiSheetPlugin
TablePlugin
TagMePlugin
TinyMCEPlugin
TwistyPlugin
WatchlistPlugin
WysiwygPlugin
modifyHeaderHandlerWysiwygPlugin
postRenderingHandlerPreferencesPlugin
WysiwygPlugin
preRenderingHandlerInterwikiPlugin
SmiliesPlugin
TablePlugin
20 plugins

 

The TWiki Plugin API

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The Application Programming Interface (API) for TWikiPlugins provides the specifications for hooking into the core TWiki code from your external Perl Plugin module. The Plugin API is new to the Production version of TWiki with the 01-Sep-2001 release.
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The Application Programming Interface (API) for TWiki Plugins provides the specifications for hooking into the core TWiki code from your external Perl Plugin module.
 

Available Core Functions

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The TWikiFuncModule (lib/TWiki/Func.pm) implements ALL official Plugin functions. Plugins should ONLY use functions published in this module.
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The TWikiFuncDotPm module (lib/TWiki/Func.pm) describes all the interfaces available to Plugins. Plugins should only use the interfaces described in this module.
 
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ALERT! If you use functions not in Func.pm, you run the risk of creating security holes. Also, your Plugin will likely break and require updating when you upgrade to a new version of TWiki.
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ALERT! Note: If you use other core functions not described in Func.pm, you run the risk of creating security holes. Also, your Plugin will likely break and require updating when you upgrade to a new version of TWiki.
 

Predefined Hooks

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In addition to TWiki core functions, Plugins can use predefined hooks, or call backs, listed in the lib/TWiki/Plugins/EmptyPlugin.pm module.
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In addition to TWiki core functions, Plugins can use predefined hooks, or callbacks, as described in the lib/TWiki/Plugins/EmptyPlugin.pm module.
 
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  • All but the initPlugin are disabled. To enable a call back, remove DISABLE_ from the function name.
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  • All but the initPlugin are disabled. To enable a callback, remove DISABLE_ from the function name.
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  • For best performance, enable only the functions you really need. NOTE: outsidePREHandler and insidePREHandler are particularly expensive.
 
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Most Plugins use either the commonTagsHandler or startRenderingHandler for rendering tasks:
  • commonTagsHandler: Use it to expand %XYZPLUGIN% and %XYZPLUGIN{...}% variables
  • startRenderingHandler: Use it for your own rendering rules or to overload TWiki's internal rendering like [[links]]
 TWiki:Codev/StepByStepRenderingOrder helps you decide which rendering handler to use.
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Hints on Writing Fast Plugins

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  • Delay the Plugin initialization to the actual function which is handling the tag. This way all the expensive initialization is done only when needed.
  • For example, use an eval block like:
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  • Delay initialization as late as possible. For example, if your Plugin is a simple syntax processor, you might delay loading extra Perl modules until you actually see the syntax in the text.
  • For example, use an eval block like this:
  eval { require IPC::Run }
return "<font color=\"red\">SamplePlugin: Can't load required modules ($@)</font>" if $@;
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  • You could return errors as strings to show what happened
 
  • You can use a flag to avoid running the initialization twice
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Plugin Version Detection

To eliminate the incompatibility problems bound to arise from active open Plugin development, a Plugin versioning system is provided for automatic compatibility checking.

  • All modules require a $VERSION='0.000' variable, beginning at 1.000.

  • The initPlugin handler should check all dependencies and return TRUE if the initialization is OK or FALSE if something went wrong.
    • The Plugin initialization code does not register a Plugin that returns FALSE (or that has no initPlugin handler).

  • $TWiki::Plugins::VERSION in the TWiki::Plugins module contains the TWiki Plugin API version, currently 6.10.
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    • You can also use the %PLUGINVERSION{}% variable to query the Plugin API version or the version of installed Plugins.
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    • You can also use the %PLUGINVERSION{}% variable to query the Plugin API version or the version of installed Plugins.
 
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Security

  • Badly written Plugins can open huge security holes in TWiki. This is especially true if care isn't taken to prevent execution of arbitrary commands on the server.
  • Don't allow sensitive configuration data to be edited by users. it is better to add sensitive configuration options to the %TWiki::cfg hash than adding it as preferences in the Plugin topic
  • Always use the TWiki::Sandbox to execute commands.
  • Always audit the Plugins you install, and make sure you are happy with the level of security provided. While every effort is made to monitor Plugin authors activities, at the end of the day they are uncontrolled user contributions.
 

Creating Plugins

With a reasonable knowledge of the Perl scripting language, you can create new Plugins or modify and extend existing ones. Basic plug-in architecture uses an Application Programming Interface (API), a set of software instructions that allow external code to interact with the main program. The TWiki Plugin API Plugins by providing a programming interface for TWiki.

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The DefaultPlugin Alternative

  • DefaultPlugin can handle some outdated TWiki variables, found, for example, in sites recently updated from an old version. Settings are in DefaultPlugin topic. You can also add your own simple custom processing rules here, though in all but very simple cases, writing a new Plugin is preferable.
 

Anatomy of a Plugin

A basic TWiki Plugin consists of two elements:

  • a Perl module, ex: MyFirstPlugin.pm
  • a documentation topic, ex: MyFirstPlugin.txt

The Perl module can be a block of code that connects with TWiki alone, or it can include other elements, like other Perl modules (including other Plugins), graphics, TWiki templates, external applications (ex: a Java applet), or just about anything else it can call. In particular, files that should be web-accessible (graphics, Java applets ...) are best placed as attachments of the MyFirstPlugin topic. Other needed Perl code is best placed in a lib/TWiki/Plugins/MyFirstPlugin/ directory.

The Plugin API handles the details of connecting your Perl module with main TWiki code. When you're familiar with the Plugin API, you're ready to develop Plugins.

Creating the Perl Module

Copy file lib/TWiki/Plugins/EmptyPlugin.pm to <name>Plugin.pm. The EmptyPlugin.pm module contains mostly empty functions, so it does nothing, but it's ready to be used. Customize it. Refer to the Plugin API specs for more information.

If your Plugin uses its own modules and objects, you must include the name of the Plugin in the package name. For example, write Package MyFirstPlugin::Attrs; instead of just Package Attrs;. Then call it using:


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use TWiki::Plugins::MyFirstPlugin::Attrs; $var = MyFirstPlugin::Attrs->new();
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use TWiki::Plugins::MyFirstPlugin::Attrs; $var = MyFirstPlugin::Attrs->new();
 
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Measuring and Improving the Plugin Performance

A high quality Plugin performs well. You can use the TWiki:Plugins.PluginBenchmarkAddOn to measure your TWiki:Plugins.PluginBenchmarks. The data is needed as part of the Documentation Topic.

See also Hints on Writing Fast Plugins.

 

Writing the Documentation Topic

The Plugin documentation topic contains usage instructions and version details. It serves the Plugin files as FileAttachments for downloading. (The doc topic is also included in the distribution package.) To create a documentation topic:

  1. Copy the Plugin topic template from TWiki.org. To copy the text, go to TWiki:Plugins/PluginPackage and:
    • enter the Plugin name in the "How to Create a Plugin" section
    • click Create
    • select all in the Edit box & copy
    • Cancel the edit
    • go back to your site to the TWiki web
    • In the GoBox enter your Plugin name, for example MyFirstPlugin, press enter and create the new topic
    • paste & save new Plugin topic on your site
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  1. Customize your Plugin topic.
    • In case you plan to publish your Plugin at TWiki.org, use Interwiki names for author names, like TWiki:Main/TWikiGuest.
  2. Save your topic, for use in packaging and publishing your Plugin.
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  1. Customize your Plugin topic.
    • Important: In case you plan to publish your Plugin on TWiki.org, use Interwiki names for author names and links to TWiki.org topics, such as TWiki:Main/TWikiGuest. This is important because links should work properly in a Plugin topic installed on any TWiki, not just on TWiki.org.
  2. Document the performance data you gathered while measuring the performance
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  1. Save your topic, for use in packaging and publishing your Plugin.
 
OUTLINE: Doc Topic Contents
Check the Plugins web on TWiki.org for the latest Plugin doc topic template. Here's a quick overview of what's covered:

Syntax Rules: <Describe any special text formatting that will be rendered.>"

Example: <Include an example of the Plugin in action. Possibly include a static HTML version of the example to compare if the installation was a success!>"

Plugin Settings: <Description and settings for custom Plugin %VARIABLES%, and those required by TWiki.>"

  • Plugins Preferences <If user settings are needed, explain... Entering values works exactly like TWikiPreferences and WebPreferences: six (6) spaces and then:>"
    • Set <EXAMPLE = value added>

Plugin Installation Instructions: <Step-by-step set-up guide, user help, whatever it takes to install and run, goes here.>"

Plugin Info: <Version, credits, history, requirements - entered in a form, displayed as a table. Both are automatically generated when you create or edit a page in the TWiki:Plugins web.>"

Packaging for Distribution

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A minimum Plugin release consists of a Perl module with a WikiName that ends in Plugin, ex: MyFirstPlugin.pm, and a documentation page with the same name(MyFirstPlugin.txt).
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The TWiki:Plugins.BuildContrib is a powerful build environment that is used by the TWiki project to build TWiki itself, as well as many of the Plugins. You don't have to use it, but it is highly recommended!
 
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  1. Distribute the Plugin files in a directory structure that mirrors TWiki. If your Plugin uses additional files, include them ALL:
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If you don't want (or can't) use the BuildContrib, then a minimum Plugin release consists of a Perl module with a WikiName that ends in Plugin, ex: MyFirstPlugin.pm, and a documentation page with the same name(MyFirstPlugin.txt).
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  1. Distribute the Plugin files in a directory structure that mirrors TWiki. If your Plugin uses additional files, include them all:
 
    • lib/TWiki/Plugins/MyFirstPlugin.pm
    • data/TWiki/MyFirstPlugin.txt
    • pub/TWiki/MyFirstPlugin/uparrow.gif [a required graphic]
  1. Create a zip archive with the Plugin name (MyFirstPlugin.zip) and add the entire directory structure from Step 1. The archive should look like this:
    • lib/TWiki/Plugins/MyFirstPlugin.pm
    • data/TWiki/MyFirstPlugin.txt
    • pub/TWiki/MyFirstPlugin/uparrow.gif

Publishing for Public Use

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You can release your tested, packaged Plugin to the TWiki community through the TWiki:Plugins web. All Plugins submitted to TWiki.org are available for download and further development in TWiki:Plugins/PluginPackage. Publish your Plugin in these steps:
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You can release your tested, packaged Plugin to the TWiki community through the TWiki:Plugins web. All Plugins submitted to TWiki.org are available for download and further development in TWiki:Plugins/PluginPackage.
 
Added:
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Publish your Plugin by following these steps:
 
  1. Post the Plugin documentation topic in the TWiki:Plugins/PluginPackage:
    • enter the Plugin name in the "How to Create a Plugin" section, for example MyFirstPlugin
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  1. Attach the distribution zip file to the topic, ex: MyFirstPlugin.zip
  2. Link from the doc page to a new, blank page named after the Plugin, and ending in Dev, ex: MyFirstPluginDev. This is the discussion page for future development. (User support for Plugins is handled in TWiki:Support.)
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  1. Put the Plugin into the CVS repository, see TWiki:Plugins/ReadmeFirst (optional)
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  1. Put the Plugin into the SVN repository, see TWiki:Plugins/ReadmeFirst (optional)
 
Added:
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NEW Once you have done the above steps once, you can use the BuildContrib to upload updates to your Plugin.
 Thank you very much for sharing your Plugin with the TWiki community smile

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Recommended Storage of Plugin Data

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Recommended Storage of Plugin Specific Data

 
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Plugins sometimes need to store data. This can be Plugin internal data like cache data, or generated data for the browser like images. The following is a recommendation where to store the data.
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Plugins sometimes need to store data. This can be Plugin internal data such as cache data, or data generated for browser consumption such as images. Plugins should store data using TWikiFuncDotPm functions that support saving and loading of topics and attachments.
 
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Where to store Plugin Internal Data

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Plugin Internal Data

 
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In case the Plugin generates data just for internal use, or data which is not specific to a topic, store it in the Plugin's attachment directory.
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You can create a Plugin "work area" using the TWiki::Func::getWorkArea() function, which gives you a persistant directory where you can store data files. By default they will not be web accessible. The directory is guaranteed to exist, and to be writable by the webserver user. For convenience, TWiki::Func::storeFile() and TWiki::Func::readFile() are provided to persistently store and retrieve simple data in this area.
 
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  • The Plugin's attachment directory is pubdir/Installweb/FooBarPlugin
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Web Accessible Data

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    • Installweb refers to the name of the web where the Plugin is installed
  • The Plugin's attachment URL is %PUBURL%/Installweb/FooBarPlugin
  • The filename should start with an underscore, followed by an identifier, e.g. _any_name.ext
    • The leading underscore avoids a nameclash with files attached to the Plugin topic
    • Use only alphanumeric characters, underscores and periods to avoid platform dependency issues and URL issues
    • Do not use subdirectories (rename and delete would fail)
  • Use Plugin API functions documented in TWikiFuncModule to ensure portability:
    • Use getPubDir() to get the attachment root directory
    • Use getUrlHost() and getPubUrlPath() to build the URL in case you create content for the browser
    • Use $installWeb to get the name of the web where the Plugin is installed
    • Create the web directory and topic attachment directory if needed
  • Hint: Package the Plugin at least with one file attachment. This ensures that the attachment directory already exists
 
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Where to Store Data for Topics using the Plugin

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Topic-specific data such as generated images can be stored in the topics attachment area, which is web accessible. Use the TWiki::Func::saveAttachment() function to store the data.
 
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In case the Plugin generates data which is specific to a topic, store it in the topic's attachment directory.
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Recommendation for file name:
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  • Prefix the filename with an underscore (the leading underscore avoids a nameclash with files attached to the same topic)
  • Identify where the attachment originated from, typically by including the Plugin name in the file name
  • Use only alphanumeric characters, underscores, dashes and periods to avoid platform dependency issues and URL issues
  • Example: _FooBarPlugin_img123.gif
 
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  • The topic's attachment directory is pubdir/Webname/TopicName
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Web specific data can be stored in the Plugin's attachment area, which is web accessible. Use the TWiki::Func::saveAttachment() function to store the data.
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  • The topic's attachment URL is %PUBURL%/Webname/TopicName
  • The filename should start with an underscore, followed by the Plugin name, an underscore and an identifier, e.g. _FooBarPlugin_any_name.ext
    • The leading underscore avoids a nameclash with files attached to the same topic
    • Use only alphanumeric characters, underscores and periods to avoid platform dependency issues and URL issues
    • Do not use subdirectories (rename and delete would fail)
  • Use Plugin API functions documented in TWikiFuncModule to ensure portability:
    • Use getPubDir() to get the attachment root directory
    • Use getUrlHost() and getPubUrlPath() to build the URL in case you create content for the browser
 
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Example code to build the file name:
sub _make_filename
{
    my ( $web, $topic, $name ) = @_;
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Recommendation for file names in Plugin attachment area:
  • Prefix the filename with an underscore
  • Include the name of the web in the filename
  • Use only alphanumeric characters, underscores, dashes and periods to avoid platform dependency issues and URL issues
  • Example: _Main_roundedge-ul.gif
 
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# Create web directory "pub/$web" if needed my $dir = TWiki::Func::getPubDir() . "/$web"; unless( -e "$dir" ) { umask( 002 ); mkdir( $dir, 0775 ); } # Create topic directory "pub/$web/$topic" if needed $dir .= "/$topic"; unless( -e "$dir" ) { umask( 002 ); mkdir( $dir, 0775 ); } return "$dir/_FooBarPlugin_$name"; }
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Maintaining Plugins

Discussions and Feedback on Plugins

Each published Plugin has a Plugin development topic on TWiki.org. Plugin development topics are named after your Plugin and end in Dev, such as MyFirstPluginDev. The Plugin development topic is a great resource to discuss feature enhancements and to get feedback from the TWiki community.

Maintaining Compatibility with Earlier TWiki Versions

The Plugin interface (TWikiFuncDotPm functions and handlers) evolve over time. TWiki 4.0 introduced new API functions to address the needs of Plugin authors. It also deprecated some functions. Some Plugins written for earlier TWiki releases using unofficial TWiki internal functions no longer work on the TWiki 4.0 codebase. All this means that some Plugins need to be updated to work on the TWiki 4.0 codebase.

Organizations typically do not upgrade to the latest TWiki for many months. However, many administrators still would like to install the latest versions of a Plugin on their older TWiki installation. This need is fullfilled if Plugins are maintained in a compatible manner.

TIP Tip: Plugins can be written to be compatible with older and newer TWiki releases. This can be done also for Plugins using unofficial TWiki internal functions of an earlier release that no longer work on the latest TWiki codebase. TWiki:TWiki.TWikiPluginsSupplement#MaintainPlugins has more.

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Handling deprecated functions

From time-to-time, the TWiki developers will add new functions to the interface (either to TWikiFuncDotPm, or new handlers). Sometimes these improvements mean that old functions have to be deprecated to keep the code manageable. When this happens, the deprecated functions will be supported in the interface for at least one more TWiki release, and probably longer, though this cannot be guaranteed.

When a plugin defines deprecated handlers, a warning will be shown in the list generated by %FAILEDPLUGINS%. Admins who see these warnings should check TWiki.org and if necessary, contact the plugin author, for an updated version of the plugin.

Updated plugins may still need to define deprecated handlers for compatibility with old TWiki versions. In this case, the plugin package that defines old handlers can suppress the warnings in %FAILEDPLUGINS%.

This is done by defining a map from the handler name to the TWiki::Plugins version in which the handler was first deprecated. For example, if we need to define the endRenderingHandler for compatibility with TWiki::Plugins versions before 1.1, we would add this to the plugin:

package TWiki::Plugins::SinkPlugin;
use vars qw( %TWikiCompatibility );
$TWikiCompatibility{endRenderingHandler} = 1.1;
 
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If the currently-running TWiki version is 1.1 or later, then the handler will not be called and the warning will not be issued. TWiki with versions of TWiki::Plugins before 1.1 will still call the handler as required.
 
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-- TWiki:Main/PeterThoeny - 14 Aug 2004
-- TWiki:Main/AndreaSterbini - 29 May 2001
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Related Topics: DeveloperDocumentationCategory, AdminDocumentationCategory, TWiki:TWiki.TWikiPluginsSupplement
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-- TWiki:Main/MikeMannix - 03 Dec 2001
 
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-- Contributors: TWiki:Main.PeterThoeny, TWiki:Main.AndreaSterbini, TWiki:MainMikeMannix, TWiki:CrawfordCurrie
 

Revision 292004-08-14 - PeterThoeny

 

TWiki Plugins

Plug-in enhanced feature add-ons, with a Plugin API for developers

Overview

You can add Plugins to extend TWiki's functionality, without altering the core program code. A plug-in approach lets you:

  • add virtually unlimited features while keeping the main TWiki code compact and efficient;
  • heavily customize an installation and still do clean updates to new versions of TWiki;
  • rapidly develop new TWiki functions in Perl using the Plugin API.

Everything to do with TWiki Plugins - demos, new releases, downloads, development, general discussion - is available at TWiki.org, in the TWiki:Plugins web.

Preinstalled Plugins

TWiki comes with a set of Plugins as part of the standard installation.

  • DefaultPlugin: Optionally handles some legacy variables from older versions of TWiki. You can control this option from TWikiPreferences. (Perl programmers can also add rules for simple custom processing.)
  • EmptyPlugin: Is a fully functional module, minus active code; it does nothing and serves as a template for new Plugin development
  • CommentPlugin: %COMMENTPLUGIN_SHORTDESCRIPTION%
  • InterwikiPlugin: Use it for shorthand linking to remote sites, ex: TWiki:Plugins expands to TWiki:Plugins on TWiki.org. You can edit the predefined set of of Wiki-related sites, and add your own
  • EditTablePlugin: Edit TWiki tables using edit fields, date pickers and drop down boxes
  • RenderListPlugin: %RENDERLISTPLUGIN_SHORTDESCRIPTION%
  • SlideShowPlugin: Create web based presentations based on topics with headings.
  • SmiliesPlugin: Render smilies as icons, like  :-) for smile or  :eek: for eek!
  • SpreadSheetPlugin: Add spreadsheet calculation like "$SUM( $ABOVE() )" to TWiki tables or anywhere in topic text
  • TablePlugin: Control attributes of tables and sorting of table columns

Installing Plugins

Each TWikiPlugin comes with full documentation: step-by-step installation instructions, a detailed description of any special requirements, version details, and a working example for testing.

Most Plugins can be installed in three easy steps, with no programming skills required:

  1. Download the zip file containing the Plugin, documentation, and any other required files, from TWiki:Plugins.
  2. Distribute the files to their proper locations - unzip the zip archive in your TWiki installation directory - if have a standard TWiki installation, this will distribute automatically. Otherwise, place the files according to the directory paths listed on the Plugin top in TWiki:Plugins.
  3. Check the demo example on the Plugin topic: if it's working, the installation was fine!

Special Requests: Some Plugins need certain Perl modules to be preinstalled on the host system. Plugins may also use other resources, like graphics, other modules, applications, templates. In these cases, detailed instructions are in the Plugin documentation.

Each Plugin has a standard release page, located in the TWiki:Plugins web at TWiki.org. In addition to the documentation topic (SomePlugin), there's a separate development page.

  • Doc page: Read all available info about the Plugin; download the attached distribution files.
  • Dev page: Post feature requests, bug reports and general dev comments; topic title ends in Dev (SomePluginDev).
  • User support: Post installation, how to use type questions (and answers, if you have them) in the TWiki:Support web.

On-Site Pretesting

To test new Plugins on your installation before making them public, you may want to use one of these two approaches:

  • Method 1: Safely test on-the-fly by creating separate Production and Test branches in your live TWiki installation.
    • Duplicate the twiki/bin and twiki/lib directories for the Test version, and adjust the paths in the new lib/TWiki.cfg. The following directories are shared: twiki/data, twiki/templates and twiki/pub.
    • Test Plugins and other new features in the Test installation until you're satisfied.
      • ALERT! If you modify topics using the new features, live users will likely see unfamiliar new META tags showing up on their pages - to avoid this, create and edit test-only topics to try out new features.
    • Copy the modified files to the Production installation. You can update a TWiki installation live and users won't even notice.

  • Method 2: List the Plugin being tested in the DISABLEDPLUGINS variable in TWikiPreferences. Redefine the DISABLEDPLUGINS variable in the Sandbox web and do the testing there.

Checking that Plugins are Working on a Live Server

InstalledPlugins shows which Plugins are: 1) installed, 2) loading properly and 3) what TWiki:Codev.PluginHandlers they invoke. Any failures are shown in the Errors section.

A Note on Plugin Performance

The performance of the system depends on the number of Plugins installed and on the Plugin implementation. Some Plugins impose no measurable performance decrease, some do. For example, outsidePREHandler is an expensive callback function, or a Plugin might use many Perl libraries that need to be initialized with each page view (unless you run mod_perl). It is recommended to measure the performance with and without a new Plugin. Example for Unix:
time wget -qO /dev/null https://wiki.ivoa.net/twiki/bin/view/TWiki/AbcPlugin

In case you need to install an "expensive" Plugin and you need its functionality only in one web you can place the Plugin topic into that web. TWiki will initialize the Plugin only if the Plugin topic is found (which won't be the case for other webs.)

Managing Plugins

When you finish installing a Plugin, you should be able to read the user instructions and go. In fact, some Plugins require additional settings or offer extra options that you have to select. Also, you may want to make a Plugin available only in certain webs, or temporarily disable it. And may want to list all available Plugins in certain topics. You can handle all of these management tasks with simple procedures.

Setting Preferences

Installed Plugins can be toggled on or off, site-wide or by web, through TWikiPreferences and individual WebPreferences:

  • All Plugin modules present in the lib/TWiki/Plugins directory are activated automatically unless disabled by the DISABLEDPLUGINS Preferences variable in TWikiPreferences. You can optionally list the installed Plugins in the INSTALLEDPLUGINS Preferences variable. This is useful to define the sequence of Plugin execution, or to specify other webs than the TWiki web for the Plugin topics. Settings in TWikiPreferences are:
    • Set INSTALLEDPLUGINS = DefaultPlugin, ...
    • Set DISABLEDPLUGINS = EmptyPlugin, ...

Plugin execution order in TWiki is determined by searching Plugin topics in a specific sequence: First, full web.topicname name, if specified in INSTALLEDPLUGINS; next, the TWiki web is searched; and finally, the current web.

Plugin-specific settings are done in individual Plugin topics. Two settings are standard for each Plugin:

  1. One line description, used to form the bullets describing the Plugins in the TextFormattingRules topic:
    • Set SHORTDESCRIPTION = Blah blah woof woof.
  2. Debug Plugin, output can be seen in data/debug.txt. Set to 0=off or 1=on:
    • Set DEBUG = 0
  • The settings can be retrieved as Preferences variables like %<pluginname>_<var>%, ex: %DEFAULTPLUGIN_SHORTDESCRIPTION% shows the description of the DefaultPlugin.

Listing Active Plugins

Plugin status variables let you list all active Plugins wherever needed. There are two list formats:

  • The %ACTIVATEDPLUGINS% variable lists activated Plugins by name. (This variable is displayed in TWikiPreferences for debugging use.)
  • The %PLUGINDESCRIPTIONS% variable displays a bullet list with a one-line description of each active Plugins. This variable is based on the %<plugin>_SHORTDESCRIPTION% Preferences variables of individual topics and is shown in TextFormattingRules.

DEMO: Automatically List Active Plugins Using Variables

Using %ACTIVATEDPLUGINS%:
On this TWiki site, the active Plugins are: SpreadSheetPlugin, BackupRestorePlugin, ColorPickerPlugin, CommentPlugin, DatePickerPlugin, EditTablePlugin, HeadlinesPlugin, InterwikiPlugin, JQueryPlugin, PreferencesPlugin, SetGetPlugin, SlideShowPlugin, SmiliesPlugin, TWikiSheetPlugin, TablePlugin, TagMePlugin, TinyMCEPlugin, TwistyPlugin, WatchlistPlugin, WysiwygPlugin.

Using %PLUGINDESCRIPTIONS%:
You can use any of these active TWiki Plugins:

  • SpreadSheetPlugin (2018-07-05, $Rev: 30478 (2018-07-16) $): Add spreadsheet calculation like "$SUM( $ABOVE() )" to TWiki tables or anywhere in topic text
  • BackupRestorePlugin (2021-03-19, $Rev: 30914 (2021-03-19) $): Administrator utility to backup, restore and upgrade a TWiki site
  • ColorPickerPlugin (2018-07-05, $Rev: 30442 (2018-07-16) $): Color picker, packaged for use in TWiki forms and TWiki applications
  • CommentPlugin (2018-07-05, $Rev: 30530 (2018-07-16) $): Quickly post comments to a page without an edit/preview/save cycle
  • DatePickerPlugin (2018-07-05, $Rev: 30446 (2018-07-16) $): Pop-up calendar with date picker, for use in TWiki forms, HTML forms and TWiki plugins
  • EditTablePlugin (2018-07-05, $Rev: 30448 (2018-07-16) $): Edit TWiki tables using edit fields, date pickers and drop down boxes
  • HeadlinesPlugin (2018-07-13, $Rev: 30560 (2018-07-16) $): Show headline news in TWiki pages based on RSS and ATOM news feeds from external sites
  • InterwikiPlugin (2018-07-05, $Rev: 30454 (2018-07-16) $): Write ExternalSite:Page to link to a page on an external site based on aliases defined in a rules topic
  • JQueryPlugin (2018-07-05, $Rev: 30456 (2018-07-16) $): jQuery JavaScript library for TWiki
  • PreferencesPlugin (2018-07-05, $Rev: 30528 (2018-07-16) $): Allows editing of preferences using fields predefined in a form
  • SetGetPlugin (2018-07-05, $Rev: 30472 (2018-07-16) $): Set and get variables and JSON objects in topics, optionally persistently across topic views
  • SlideShowPlugin (2018-07-05, $Rev: 30474 (2018-07-16) $): Create web based presentations based on topics with headings.
  • SmiliesPlugin (2018-07-05, $Rev: 30476 (2018-07-16) $): Render smilies as icons, like  :-) for smile or  :eek: for eek!
  • TWikiSheetPlugin (2018-07-15, $Rev: 30604 (2018-07-16) $): Add TWiki Sheet spreadsheet functionality to TWiki tables
  • TablePlugin (2018-07-05, $Rev: 30480 (2018-07-16) $): Control attributes of tables and sorting of table columns
  • TagMePlugin (2018-07-05, $Rev: 30482 (2018-07-16) $): Tag wiki content collectively or authoritatively to find content by keywords
  • TinyMCEPlugin (2021-06-09, $Rev: 31045 (2021-06-09) $): Integration of the Tiny MCE WYSIWYG Editor
  • TwistyPlugin (2018-07-06, $Rev: 30497 (2018-07-16) $): Twisty section JavaScript library to open/close content dynamically
  • WatchlistPlugin (2018-07-10, $Rev: 30536 (2018-07-16) $): Watch topics of interest and get notified of changes by e-mail
  • WysiwygPlugin (2018-07-06, $Rev: 30528 (2018-07-16) $): Translator framework for WYSIWYG editors

The TWiki Plugin API

The Application Programming Interface (API) for TWikiPlugins provides the specifications for hooking into the core TWiki code from your external Perl Plugin module. The Plugin API is new to the Production version of TWiki with the 01-Sep-2001 release.

Available Core Functions

The TWikiFuncModule (lib/TWiki/Func.pm) implements ALL official Plugin functions. Plugins should ONLY use functions published in this module.

ALERT! If you use functions not in Func.pm, you run the risk of creating security holes. Also, your Plugin will likely break and require updating when you upgrade to a new version of TWiki.

Predefined Hooks

In addition to TWiki core functions, Plugins can use predefined hooks, or call backs, listed in the lib/TWiki/Plugins/EmptyPlugin.pm module.

  • All but the initPlugin are disabled. To enable a call back, remove DISABLE_ from the function name.
  • For best performance, enable only the functions you really need. NOTE: outsidePREHandler and insidePREHandler are particularly expensive.

Most Plugins use either the commonTagsHandler or startRenderingHandler for rendering tasks:

  • commonTagsHandler: Use it to expand %XYZPLUGIN% and %XYZPLUGIN{...}% variables
  • startRenderingHandler: Use it for your own rendering rules or to overload TWiki's internal rendering like [[links]]

TWiki:Codev/StepByStepRenderingOrder helps you decide which rendering handler to use.

Hints on Writing Fast Plugins

  • Delay the Plugin initialization to the actual function which is handling the tag. This way all the expensive initialization is done only when needed.
  • For example, use an eval block like:
    eval { require IPC::Run }
    return "<font color=\"red\">SamplePlugin: Can't load required modules ($@)</font>" if $@;
  • You could return errors as strings to show what happened
  • You can use a flag to avoid running the initialization twice

Plugin Version Detection

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To eliminate the incompatibility problems bound to arise from active open Plugin development, a Plugin versioning system and an API GetVersion detection routine are provided for automatic compatibility checking.
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To eliminate the incompatibility problems bound to arise from active open Plugin development, a Plugin versioning system is provided for automatic compatibility checking.
 
  • All modules require a $VERSION='0.000' variable, beginning at 1.000.

  • The initPlugin handler should check all dependencies and return TRUE if the initialization is OK or FALSE if something went wrong.
    • The Plugin initialization code does not register a Plugin that returns FALSE (or that has no initPlugin handler).
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  • $TWiki::Plugins::VERSION in the TWiki::Plugins module contains the TWiki Plugin API version, currently 6.10.
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    • You can also use the %PLUGINVERSION{}% variable to query the Plugin API version or the version of installed Plugins.
 

Creating Plugins

With a reasonable knowledge of the Perl scripting language, you can create new Plugins or modify and extend existing ones. Basic plug-in architecture uses an Application Programming Interface (API), a set of software instructions that allow external code to interact with the main program. The TWiki Plugin API Plugins by providing a programming interface for TWiki.

The DefaultPlugin Alternative

  • DefaultPlugin can handle some outdated TWiki variables, found, for example, in sites recently updated from an old version. Settings are in DefaultPlugin topic. You can also add your own simple custom processing rules here, though in all but very simple cases, writing a new Plugin is preferable.

Anatomy of a Plugin

A basic TWiki Plugin consists of two elements:

  • a Perl module, ex: MyFirstPlugin.pm
  • a documentation topic, ex: MyFirstPlugin.txt

The Perl module can be a block of code that connects with TWiki alone, or it can include other elements, like other Perl modules (including other Plugins), graphics, TWiki templates, external applications (ex: a Java applet), or just about anything else it can call. In particular, files that should be web-accessible (graphics, Java applets ...) are best placed as attachments of the MyFirstPlugin topic. Other needed Perl code is best placed in a lib/TWiki/Plugins/MyFirstPlugin/ directory.

The Plugin API handles the details of connecting your Perl module with main TWiki code. When you're familiar with the Plugin API, you're ready to develop Plugins.

Creating the Perl Module

Copy file lib/TWiki/Plugins/EmptyPlugin.pm to <name>Plugin.pm. The EmptyPlugin.pm module contains mostly empty functions, so it does nothing, but it's ready to be used. Customize it. Refer to the Plugin API specs for more information.

If your Plugin uses its own modules and objects, you must include the name of the Plugin in the package name. For example, write Package MyFirstPlugin::Attrs; instead of just Package Attrs;. Then call it using:

  use TWiki::Plugins::MyFirstPlugin::Attrs;
  $var = MyFirstPlugin::Attrs->new();

Writing the Documentation Topic

The Plugin documentation topic contains usage instructions and version details. It serves the Plugin files as FileAttachments for downloading. (The doc topic is also included in the distribution package.) To create a documentation topic:

  1. Copy the Plugin topic template from TWiki.org. To copy the text, go to TWiki:Plugins/PluginPackage and:
    • enter the Plugin name in the "How to Create a Plugin" section
    • click Create
    • select all in the Edit box & copy
    • Cancel the edit
    • go back to your site to the TWiki web
    • In the GoBox enter your Plugin name, for example MyFirstPlugin, press enter and create the new topic
    • paste & save new Plugin topic on your site
  2. Customize your Plugin topic.
    • In case you plan to publish your Plugin at TWiki.org, use Interwiki names for author names, like TWiki:Main/TWikiGuest.
  3. Save your topic, for use in packaging and publishing your Plugin.

OUTLINE: Doc Topic Contents
Check the Plugins web on TWiki.org for the latest Plugin doc topic template. Here's a quick overview of what's covered:

Syntax Rules: <Describe any special text formatting that will be rendered.>"

Example: <Include an example of the Plugin in action. Possibly include a static HTML version of the example to compare if the installation was a success!>"

Plugin Settings: <Description and settings for custom Plugin %VARIABLES%, and those required by TWiki.>"

  • Plugins Preferences <If user settings are needed, explain... Entering values works exactly like TWikiPreferences and WebPreferences: six (6) spaces and then:>"
    • Set <EXAMPLE = value added>

Plugin Installation Instructions: <Step-by-step set-up guide, user help, whatever it takes to install and run, goes here.>"

Plugin Info: <Version, credits, history, requirements - entered in a form, displayed as a table. Both are automatically generated when you create or edit a page in the TWiki:Plugins web.>"

Packaging for Distribution

A minimum Plugin release consists of a Perl module with a WikiName that ends in Plugin, ex: MyFirstPlugin.pm, and a documentation page with the same name(MyFirstPlugin.txt).

  1. Distribute the Plugin files in a directory structure that mirrors TWiki. If your Plugin uses additional files, include them ALL:
    • lib/TWiki/Plugins/MyFirstPlugin.pm
    • data/TWiki/MyFirstPlugin.txt
    • pub/TWiki/MyFirstPlugin/uparrow.gif [a required graphic]
  2. Create a zip archive with the Plugin name (MyFirstPlugin.zip) and add the entire directory structure from Step 1. The archive should look like this:
    • lib/TWiki/Plugins/MyFirstPlugin.pm
    • data/TWiki/MyFirstPlugin.txt
    • pub/TWiki/MyFirstPlugin/uparrow.gif

Publishing for Public Use

You can release your tested, packaged Plugin to the TWiki community through the TWiki:Plugins web. All Plugins submitted to TWiki.org are available for download and further development in TWiki:Plugins/PluginPackage. Publish your Plugin in these steps:

  1. Post the Plugin documentation topic in the TWiki:Plugins/PluginPackage:
    • enter the Plugin name in the "How to Create a Plugin" section, for example MyFirstPlugin
    • paste in the topic text from Creating Plugin Documentation and save
  2. Attach the distribution zip file to the topic, ex: MyFirstPlugin.zip
  3. Link from the doc page to a new, blank page named after the Plugin, and ending in Dev, ex: MyFirstPluginDev. This is the discussion page for future development. (User support for Plugins is handled in TWiki:Support.)
  4. Put the Plugin into the CVS repository, see TWiki:Plugins/ReadmeFirst (optional)

Thank you very much for sharing your Plugin with the TWiki community smile

Recommended Storage of Plugin Data

Plugins sometimes need to store data. This can be Plugin internal data like cache data, or generated data for the browser like images. The following is a recommendation where to store the data.

Where to store Plugin Internal Data

In case the Plugin generates data just for internal use, or data which is not specific to a topic, store it in the Plugin's attachment directory.

  • The Plugin's attachment directory is pubdir/Installweb/FooBarPlugin
    • Installweb refers to the name of the web where the Plugin is installed
  • The Plugin's attachment URL is %PUBURL%/Installweb/FooBarPlugin
  • The filename should start with an underscore, followed by an identifier, e.g. _any_name.ext
    • The leading underscore avoids a nameclash with files attached to the Plugin topic
    • Use only alphanumeric characters, underscores and periods to avoid platform dependency issues and URL issues
    • Do not use subdirectories (rename and delete would fail)
  • Use Plugin API functions documented in TWikiFuncModule to ensure portability:
    • Use getPubDir() to get the attachment root directory
    • Use getUrlHost() and getPubUrlPath() to build the URL in case you create content for the browser
    • Use $installWeb to get the name of the web where the Plugin is installed
    • Create the web directory and topic attachment directory if needed
  • Hint: Package the Plugin at least with one file attachment. This ensures that the attachment directory already exists

Where to Store Data for Topics using the Plugin

In case the Plugin generates data which is specific to a topic, store it in the topic's attachment directory.

  • The topic's attachment directory is pubdir/Webname/TopicName
  • The topic's attachment URL is %PUBURL%/Webname/TopicName
  • The filename should start with an underscore, followed by the Plugin name, an underscore and an identifier, e.g. _FooBarPlugin_any_name.ext
    • The leading underscore avoids a nameclash with files attached to the same topic
    • Use only alphanumeric characters, underscores and periods to avoid platform dependency issues and URL issues
    • Do not use subdirectories (rename and delete would fail)
  • Use Plugin API functions documented in TWikiFuncModule to ensure portability:
    • Use getPubDir() to get the attachment root directory
    • Use getUrlHost() and getPubUrlPath() to build the URL in case you create content for the browser

Example code to build the file name:

sub _make_filename
{
    my ( $web, $topic, $name ) = @_;

    # Create web directory "pub/$web" if needed
    my $dir = TWiki::Func::getPubDir() . "/$web";
    unless( -e "$dir" ) {
        umask( 002 );
        mkdir( $dir, 0775 );
    }
    # Create topic directory "pub/$web/$topic" if needed
    $dir .= "/$topic";
    unless( -e "$dir" ) {
        umask( 002 );
        mkdir( $dir, 0775 );
    }
    return "$dir/_FooBarPlugin_$name";
}
Changed:
<
<
-- TWiki:Main/PeterThoeny - 18 May 2004
>
>
-- TWiki:Main/PeterThoeny - 14 Aug 2004
 -- TWiki:Main/AndreaSterbini - 29 May 2001
-- TWiki:Main/MikeMannix - 03 Dec 2001

Revision 282004-08-08 - PeterThoeny

 

TWiki Plugins

Plug-in enhanced feature add-ons, with a Plugin API for developers

Overview

You can add Plugins to extend TWiki's functionality, without altering the core program code. A plug-in approach lets you:

  • add virtually unlimited features while keeping the main TWiki code compact and efficient;
  • heavily customize an installation and still do clean updates to new versions of TWiki;
  • rapidly develop new TWiki functions in Perl using the Plugin API.

Everything to do with TWiki Plugins - demos, new releases, downloads, development, general discussion - is available at TWiki.org, in the TWiki:Plugins web.

Preinstalled Plugins

TWiki comes with a set of Plugins as part of the standard installation.

  • DefaultPlugin: Optionally handles some legacy variables from older versions of TWiki. You can control this option from TWikiPreferences. (Perl programmers can also add rules for simple custom processing.)
Changed:
<
<
  • EmptyPlugin: Is a fully functional module, minus active code; it does nothing and serves as a template for new Plugin development.
  • InterwikiPlugin: Use it for shorthand linking to remote sites, ex: TWiki:Plugins expands to TWiki:Plugins on TWiki.org. You can edit the predefined set of of Wiki-related sites, and add your own.
>
>
  • EmptyPlugin: Is a fully functional module, minus active code; it does nothing and serves as a template for new Plugin development
  • CommentPlugin: %COMMENTPLUGIN_SHORTDESCRIPTION%
Added:
>
>
  • InterwikiPlugin: Use it for shorthand linking to remote sites, ex: TWiki:Plugins expands to TWiki:Plugins on TWiki.org. You can edit the predefined set of of Wiki-related sites, and add your own
 
  • EditTablePlugin: Edit TWiki tables using edit fields, date pickers and drop down boxes
  • RenderListPlugin: %RENDERLISTPLUGIN_SHORTDESCRIPTION%
  • SlideShowPlugin: Create web based presentations based on topics with headings.
  • SmiliesPlugin: Render smilies as icons, like  :-) for smile or  :eek: for eek!
  • SpreadSheetPlugin: Add spreadsheet calculation like "$SUM( $ABOVE() )" to TWiki tables or anywhere in topic text
  • TablePlugin: Control attributes of tables and sorting of table columns

Installing Plugins

Each TWikiPlugin comes with full documentation: step-by-step installation instructions, a detailed description of any special requirements, version details, and a working example for testing.

Most Plugins can be installed in three easy steps, with no programming skills required:

  1. Download the zip file containing the Plugin, documentation, and any other required files, from TWiki:Plugins.
  2. Distribute the files to their proper locations - unzip the zip archive in your TWiki installation directory - if have a standard TWiki installation, this will distribute automatically. Otherwise, place the files according to the directory paths listed on the Plugin top in TWiki:Plugins.
  3. Check the demo example on the Plugin topic: if it's working, the installation was fine!

Special Requests: Some Plugins need certain Perl modules to be preinstalled on the host system. Plugins may also use other resources, like graphics, other modules, applications, templates. In these cases, detailed instructions are in the Plugin documentation.

Each Plugin has a standard release page, located in the TWiki:Plugins web at TWiki.org. In addition to the documentation topic (SomePlugin), there's a separate development page.

  • Doc page: Read all available info about the Plugin; download the attached distribution files.
  • Dev page: Post feature requests, bug reports and general dev comments; topic title ends in Dev (SomePluginDev).
  • User support: Post installation, how to use type questions (and answers, if you have them) in the TWiki:Support web.

On-Site Pretesting

To test new Plugins on your installation before making them public, you may want to use one of these two approaches:

  • Method 1: Safely test on-the-fly by creating separate Production and Test branches in your live TWiki installation.
    • Duplicate the twiki/bin and twiki/lib directories for the Test version, and adjust the paths in the new lib/TWiki.cfg. The following directories are shared: twiki/data, twiki/templates and twiki/pub.
    • Test Plugins and other new features in the Test installation until you're satisfied.
      • ALERT! If you modify topics using the new features, live users will likely see unfamiliar new META tags showing up on their pages - to avoid this, create and edit test-only topics to try out new features.
    • Copy the modified files to the Production installation. You can update a TWiki installation live and users won't even notice.

  • Method 2: List the Plugin being tested in the DISABLEDPLUGINS variable in TWikiPreferences. Redefine the DISABLEDPLUGINS variable in the Sandbox web and do the testing there.

Checking that Plugins are Working on a Live Server

InstalledPlugins shows which Plugins are: 1) installed, 2) loading properly and 3) what TWiki:Codev.PluginHandlers they invoke. Any failures are shown in the Errors section.

A Note on Plugin Performance

The performance of the system depends on the number of Plugins installed and on the Plugin implementation. Some Plugins impose no measurable performance decrease, some do. For example, outsidePREHandler is an expensive callback function, or a Plugin might use many Perl libraries that need to be initialized with each page view (unless you run mod_perl). It is recommended to measure the performance with and without a new Plugin. Example for Unix:
time wget -qO /dev/null https://wiki.ivoa.net/twiki/bin/view/TWiki/AbcPlugin

In case you need to install an "expensive" Plugin and you need its functionality only in one web you can place the Plugin topic into that web. TWiki will initialize the Plugin only if the Plugin topic is found (which won't be the case for other webs.)

Managing Plugins

When you finish installing a Plugin, you should be able to read the user instructions and go. In fact, some Plugins require additional settings or offer extra options that you have to select. Also, you may want to make a Plugin available only in certain webs, or temporarily disable it. And may want to list all available Plugins in certain topics. You can handle all of these management tasks with simple procedures.

Setting Preferences

Installed Plugins can be toggled on or off, site-wide or by web, through TWikiPreferences and individual WebPreferences:

  • All Plugin modules present in the lib/TWiki/Plugins directory are activated automatically unless disabled by the DISABLEDPLUGINS Preferences variable in TWikiPreferences. You can optionally list the installed Plugins in the INSTALLEDPLUGINS Preferences variable. This is useful to define the sequence of Plugin execution, or to specify other webs than the TWiki web for the Plugin topics. Settings in TWikiPreferences are:
    • Set INSTALLEDPLUGINS = DefaultPlugin, ...
    • Set DISABLEDPLUGINS = EmptyPlugin, ...

Plugin execution order in TWiki is determined by searching Plugin topics in a specific sequence: First, full web.topicname name, if specified in INSTALLEDPLUGINS; next, the TWiki web is searched; and finally, the current web.

Plugin-specific settings are done in individual Plugin topics. Two settings are standard for each Plugin:

  1. One line description, used to form the bullets describing the Plugins in the TextFormattingRules topic:
    • Set SHORTDESCRIPTION = Blah blah woof woof.
  2. Debug Plugin, output can be seen in data/debug.txt. Set to 0=off or 1=on:
    • Set DEBUG = 0
  • The settings can be retrieved as Preferences variables like %<pluginname>_<var>%, ex: %DEFAULTPLUGIN_SHORTDESCRIPTION% shows the description of the DefaultPlugin.

Listing Active Plugins

Plugin status variables let you list all active Plugins wherever needed. There are two list formats:

  • The %ACTIVATEDPLUGINS% variable lists activated Plugins by name. (This variable is displayed in TWikiPreferences for debugging use.)
  • The %PLUGINDESCRIPTIONS% variable displays a bullet list with a one-line description of each active Plugins. This variable is based on the %<plugin>_SHORTDESCRIPTION% Preferences variables of individual topics and is shown in TextFormattingRules.

DEMO: Automatically List Active Plugins Using Variables

Using %ACTIVATEDPLUGINS%:
On this TWiki site, the active Plugins are: SpreadSheetPlugin, BackupRestorePlugin, ColorPickerPlugin, CommentPlugin, DatePickerPlugin, EditTablePlugin, HeadlinesPlugin, InterwikiPlugin, JQueryPlugin, PreferencesPlugin, SetGetPlugin, SlideShowPlugin, SmiliesPlugin, TWikiSheetPlugin, TablePlugin, TagMePlugin, TinyMCEPlugin, TwistyPlugin, WatchlistPlugin, WysiwygPlugin.

Using %PLUGINDESCRIPTIONS%:
You can use any of these active TWiki Plugins:

  • SpreadSheetPlugin (2018-07-05, $Rev: 30478 (2018-07-16) $): Add spreadsheet calculation like "$SUM( $ABOVE() )" to TWiki tables or anywhere in topic text
  • BackupRestorePlugin (2021-03-19, $Rev: 30914 (2021-03-19) $): Administrator utility to backup, restore and upgrade a TWiki site
  • ColorPickerPlugin (2018-07-05, $Rev: 30442 (2018-07-16) $): Color picker, packaged for use in TWiki forms and TWiki applications
  • CommentPlugin (2018-07-05, $Rev: 30530 (2018-07-16) $): Quickly post comments to a page without an edit/preview/save cycle
  • DatePickerPlugin (2018-07-05, $Rev: 30446 (2018-07-16) $): Pop-up calendar with date picker, for use in TWiki forms, HTML forms and TWiki plugins
  • EditTablePlugin (2018-07-05, $Rev: 30448 (2018-07-16) $): Edit TWiki tables using edit fields, date pickers and drop down boxes
  • HeadlinesPlugin (2018-07-13, $Rev: 30560 (2018-07-16) $): Show headline news in TWiki pages based on RSS and ATOM news feeds from external sites
  • InterwikiPlugin (2018-07-05, $Rev: 30454 (2018-07-16) $): Write ExternalSite:Page to link to a page on an external site based on aliases defined in a rules topic
  • JQueryPlugin (2018-07-05, $Rev: 30456 (2018-07-16) $): jQuery JavaScript library for TWiki
  • PreferencesPlugin (2018-07-05, $Rev: 30528 (2018-07-16) $): Allows editing of preferences using fields predefined in a form
  • SetGetPlugin (2018-07-05, $Rev: 30472 (2018-07-16) $): Set and get variables and JSON objects in topics, optionally persistently across topic views
  • SlideShowPlugin (2018-07-05, $Rev: 30474 (2018-07-16) $): Create web based presentations based on topics with headings.
  • SmiliesPlugin (2018-07-05, $Rev: 30476 (2018-07-16) $): Render smilies as icons, like  :-) for smile or  :eek: for eek!
  • TWikiSheetPlugin (2018-07-15, $Rev: 30604 (2018-07-16) $): Add TWiki Sheet spreadsheet functionality to TWiki tables
  • TablePlugin (2018-07-05, $Rev: 30480 (2018-07-16) $): Control attributes of tables and sorting of table columns
  • TagMePlugin (2018-07-05, $Rev: 30482 (2018-07-16) $): Tag wiki content collectively or authoritatively to find content by keywords
  • TinyMCEPlugin (2021-06-09, $Rev: 31045 (2021-06-09) $): Integration of the Tiny MCE WYSIWYG Editor
  • TwistyPlugin (2018-07-06, $Rev: 30497 (2018-07-16) $): Twisty section JavaScript library to open/close content dynamically
  • WatchlistPlugin (2018-07-10, $Rev: 30536 (2018-07-16) $): Watch topics of interest and get notified of changes by e-mail
  • WysiwygPlugin (2018-07-06, $Rev: 30528 (2018-07-16) $): Translator framework for WYSIWYG editors

The TWiki Plugin API

The Application Programming Interface (API) for TWikiPlugins provides the specifications for hooking into the core TWiki code from your external Perl Plugin module. The Plugin API is new to the Production version of TWiki with the 01-Sep-2001 release.

Available Core Functions

The TWikiFuncModule (lib/TWiki/Func.pm) implements ALL official Plugin functions. Plugins should ONLY use functions published in this module.

ALERT! If you use functions not in Func.pm, you run the risk of creating security holes. Also, your Plugin will likely break and require updating when you upgrade to a new version of TWiki.

Predefined Hooks

In addition to TWiki core functions, Plugins can use predefined hooks, or call backs, listed in the lib/TWiki/Plugins/EmptyPlugin.pm module.

  • All but the initPlugin are disabled. To enable a call back, remove DISABLE_ from the function name.
  • For best performance, enable only the functions you really need. NOTE: outsidePREHandler and insidePREHandler are particularly expensive.

Most Plugins use either the commonTagsHandler or startRenderingHandler for rendering tasks:

  • commonTagsHandler: Use it to expand %XYZPLUGIN% and %XYZPLUGIN{...}% variables
  • startRenderingHandler: Use it for your own rendering rules or to overload TWiki's internal rendering like [[links]]

TWiki:Codev/StepByStepRenderingOrder helps you decide which rendering handler to use.

Hints on Writing Fast Plugins

  • Delay the Plugin initialization to the actual function which is handling the tag. This way all the expensive initialization is done only when needed.
  • For example, use an eval block like:
    eval { require IPC::Run }
    return "<font color=\"red\">SamplePlugin: Can't load required modules ($@)</font>" if $@;
  • You could return errors as strings to show what happened
  • You can use a flag to avoid running the initialization twice

Plugin Version Detection

To eliminate the incompatibility problems bound to arise from active open Plugin development, a Plugin versioning system and an API GetVersion detection routine are provided for automatic compatibility checking.

  • All modules require a $VERSION='0.000' variable, beginning at 1.000.

  • The initPlugin handler should check all dependencies and return TRUE if the initialization is OK or FALSE if something went wrong.
    • The Plugin initialization code does not register a Plugin that returns FALSE (or that has no initPlugin handler).

Creating Plugins

With a reasonable knowledge of the Perl scripting language, you can create new Plugins or modify and extend existing ones. Basic plug-in architecture uses an Application Programming Interface (API), a set of software instructions that allow external code to interact with the main program. The TWiki Plugin API Plugins by providing a programming interface for TWiki.

The DefaultPlugin Alternative

  • DefaultPlugin can handle some outdated TWiki variables, found, for example, in sites recently updated from an old version. Settings are in DefaultPlugin topic. You can also add your own simple custom processing rules here, though in all but very simple cases, writing a new Plugin is preferable.

Anatomy of a Plugin

A basic TWiki Plugin consists of two elements:

  • a Perl module, ex: MyFirstPlugin.pm
  • a documentation topic, ex: MyFirstPlugin.txt

The Perl module can be a block of code that connects with TWiki alone, or it can include other elements, like other Perl modules (including other Plugins), graphics, TWiki templates, external applications (ex: a Java applet), or just about anything else it can call. In particular, files that should be web-accessible (graphics, Java applets ...) are best placed as attachments of the MyFirstPlugin topic. Other needed Perl code is best placed in a lib/TWiki/Plugins/MyFirstPlugin/ directory.

The Plugin API handles the details of connecting your Perl module with main TWiki code. When you're familiar with the Plugin API, you're ready to develop Plugins.

Creating the Perl Module

Copy file lib/TWiki/Plugins/EmptyPlugin.pm to <name>Plugin.pm. The EmptyPlugin.pm module contains mostly empty functions, so it does nothing, but it's ready to be used. Customize it. Refer to the Plugin API specs for more information.

If your Plugin uses its own modules and objects, you must include the name of the Plugin in the package name. For example, write Package MyFirstPlugin::Attrs; instead of just Package Attrs;. Then call it using:

  use TWiki::Plugins::MyFirstPlugin::Attrs;
  $var = MyFirstPlugin::Attrs->new();

Writing the Documentation Topic

The Plugin documentation topic contains usage instructions and version details. It serves the Plugin files as FileAttachments for downloading. (The doc topic is also included in the distribution package.) To create a documentation topic:

  1. Copy the Plugin topic template from TWiki.org. To copy the text, go to TWiki:Plugins/PluginPackage and:
    • enter the Plugin name in the "How to Create a Plugin" section
    • click Create
    • select all in the Edit box & copy
    • Cancel the edit
    • go back to your site to the TWiki web
    • In the GoBox enter your Plugin name, for example MyFirstPlugin, press enter and create the new topic
    • paste & save new Plugin topic on your site
  2. Customize your Plugin topic.
    • In case you plan to publish your Plugin at TWiki.org, use Interwiki names for author names, like TWiki:Main/TWikiGuest.
  3. Save your topic, for use in packaging and publishing your Plugin.

OUTLINE: Doc Topic Contents
Check the Plugins web on TWiki.org for the latest Plugin doc topic template. Here's a quick overview of what's covered:

Syntax Rules: <Describe any special text formatting that will be rendered.>"

Example: <Include an example of the Plugin in action. Possibly include a static HTML version of the example to compare if the installation was a success!>"

Plugin Settings: <Description and settings for custom Plugin %VARIABLES%, and those required by TWiki.>"

  • Plugins Preferences <If user settings are needed, explain... Entering values works exactly like TWikiPreferences and WebPreferences: six (6) spaces and then:>"
    • Set <EXAMPLE = value added>

Plugin Installation Instructions: <Step-by-step set-up guide, user help, whatever it takes to install and run, goes here.>"

Plugin Info: <Version, credits, history, requirements - entered in a form, displayed as a table. Both are automatically generated when you create or edit a page in the TWiki:Plugins web.>"

Packaging for Distribution

A minimum Plugin release consists of a Perl module with a WikiName that ends in Plugin, ex: MyFirstPlugin.pm, and a documentation page with the same name(MyFirstPlugin.txt).

  1. Distribute the Plugin files in a directory structure that mirrors TWiki. If your Plugin uses additional files, include them ALL:
    • lib/TWiki/Plugins/MyFirstPlugin.pm
    • data/TWiki/MyFirstPlugin.txt
    • pub/TWiki/MyFirstPlugin/uparrow.gif [a required graphic]
  2. Create a zip archive with the Plugin name (MyFirstPlugin.zip) and add the entire directory structure from Step 1. The archive should look like this:
    • lib/TWiki/Plugins/MyFirstPlugin.pm
    • data/TWiki/MyFirstPlugin.txt
    • pub/TWiki/MyFirstPlugin/uparrow.gif

Publishing for Public Use

You can release your tested, packaged Plugin to the TWiki community through the TWiki:Plugins web. All Plugins submitted to TWiki.org are available for download and further development in TWiki:Plugins/PluginPackage. Publish your Plugin in these steps:

  1. Post the Plugin documentation topic in the TWiki:Plugins/PluginPackage:
    • enter the Plugin name in the "How to Create a Plugin" section, for example MyFirstPlugin
    • paste in the topic text from Creating Plugin Documentation and save
  2. Attach the distribution zip file to the topic, ex: MyFirstPlugin.zip
  3. Link from the doc page to a new, blank page named after the Plugin, and ending in Dev, ex: MyFirstPluginDev. This is the discussion page for future development. (User support for Plugins is handled in TWiki:Support.)
  4. Put the Plugin into the CVS repository, see TWiki:Plugins/ReadmeFirst (optional)

Thank you very much for sharing your Plugin with the TWiki community smile

Recommended Storage of Plugin Data

Plugins sometimes need to store data. This can be Plugin internal data like cache data, or generated data for the browser like images. The following is a recommendation where to store the data.

Where to store Plugin Internal Data

In case the Plugin generates data just for internal use, or data which is not specific to a topic, store it in the Plugin's attachment directory.

  • The Plugin's attachment directory is pubdir/Installweb/FooBarPlugin
    • Installweb refers to the name of the web where the Plugin is installed
  • The Plugin's attachment URL is %PUBURL%/Installweb/FooBarPlugin
  • The filename should start with an underscore, followed by an identifier, e.g. _any_name.ext
    • The leading underscore avoids a nameclash with files attached to the Plugin topic
    • Use only alphanumeric characters, underscores and periods to avoid platform dependency issues and URL issues
    • Do not use subdirectories (rename and delete would fail)
  • Use Plugin API functions documented in TWikiFuncModule to ensure portability:
    • Use getPubDir() to get the attachment root directory
    • Use getUrlHost() and getPubUrlPath() to build the URL in case you create content for the browser
    • Use $installWeb to get the name of the web where the Plugin is installed
    • Create the web directory and topic attachment directory if needed
  • Hint: Package the Plugin at least with one file attachment. This ensures that the attachment directory already exists

Where to Store Data for Topics using the Plugin

In case the Plugin generates data which is specific to a topic, store it in the topic's attachment directory.

  • The topic's attachment directory is pubdir/Webname/TopicName
  • The topic's attachment URL is %PUBURL%/Webname/TopicName
  • The filename should start with an underscore, followed by the Plugin name, an underscore and an identifier, e.g. _FooBarPlugin_any_name.ext
    • The leading underscore avoids a nameclash with files attached to the same topic
    • Use only alphanumeric characters, underscores and periods to avoid platform dependency issues and URL issues
    • Do not use subdirectories (rename and delete would fail)
  • Use Plugin API functions documented in TWikiFuncModule to ensure portability:
    • Use getPubDir() to get the attachment root directory
    • Use getUrlHost() and getPubUrlPath() to build the URL in case you create content for the browser

Example code to build the file name:

sub _make_filename
{
    my ( $web, $topic, $name ) = @_;

    # Create web directory "pub/$web" if needed
    my $dir = TWiki::Func::getPubDir() . "/$web";
    unless( -e "$dir" ) {
        umask( 002 );
        mkdir( $dir, 0775 );
    }
    # Create topic directory "pub/$web/$topic" if needed
    $dir .= "/$topic";
    unless( -e "$dir" ) {
        umask( 002 );
        mkdir( $dir, 0775 );
    }
    return "$dir/_FooBarPlugin_$name";
}

-- TWiki:Main/PeterThoeny - 18 May 2004
-- TWiki:Main/AndreaSterbini - 29 May 2001
-- TWiki:Main/MikeMannix - 03 Dec 2001

Revision 272004-05-18 - PeterThoeny

Changed:
<
<

TWiki Plugins

Plug-in enhanced feature add-ons, with a Plugin API for developers

Overview

You can add Plugins to extend TWiki's functionality, without altering the core program code. A plug-in approach lets you:

  • add virtually unlimited features while keeping the main TWiki code compact and efficient;
  • heavily customize an installation and still do clean updates to new versions of TWiki;
  • rapidly develop new TWiki functions in Perl using the Plugin API.

Everything to do with TWiki Plugins - demos, new releases, downloads, development, general discussion - is available at TWiki.org, in the TWiki:Plugins web.

Preinstalled Plugins

TWiki comes with a set of Plugins as part of the standard installation.

  • DefaultPlugin: Optionally handles some legacy variables from older versions of TWiki. You can control this option from TWikiPreferences. (Perl programmers can also add rules for simple custom processing.)
  • EmptyPlugin: Is a fully functional module, minus active code; it does nothing and serves as a template for new Plugin development.
  • InterwikiPlugin: Use it for shorthand linking to remote sites, ex: TWiki:Plugins expands to TWiki:Plugins on TWiki.org. You can edit the predefined set of of Wiki-related sites, and add your own.
  • EditTablePlugin: Edit TWiki tables using edit fields, date pickers and drop down boxes
  • RenderListPlugin: %RENDERLISTPLUGIN_SHORTDESCRIPTION%
  • SlideShowPlugin: Create web based presentations based on topics with headings.
  • SmiliesPlugin: Render smilies as icons, like  :-) for smile or  :eek: for eek!
  • SpreadSheetPlugin: Add spreadsheet calculation like "$SUM( $ABOVE() )" to TWiki tables or anywhere in topic text
  • TablePlugin: Control attributes of tables and sorting of table columns

Installing Plugins

Each TWikiPlugin comes with full documentation: step-by-step installation instructions, a detailed description of any special requirements, version details, and a working example for testing.

Most Plugins can be installed in three easy steps, with no programming skills required:

  1. Download the zip file containing the Plugin, documentation, and any other required files, from TWiki:Plugins.
  2. Distribute the files to their proper locations - unzip the zip archive in your TWiki installation directory - if have a standard TWiki installation, this will distribute automatically. Otherwise, place the files according to the directory paths listed on the Plugin top in TWiki:Plugins.
  3. Check the demo example on the Plugin topic: if it's working, the installation was fine!

Special Requests: Some Plugins need certain Perl modules to be preinstalled on the host system. Plugins may also use other resources, like graphics, other modules, applications, templates. In these cases, detailed instructions are in the Plugin documentation.

Each Plugin has a standard release page, located in the TWiki:Plugins web at TWiki.org. In addition to the documentation topic (SomePlugin), there's a separate development page.

  • Doc page: Read all available info about the Plugin; download the attached distribution files.
  • Dev page: Post feature requests, bug reports and general dev comments; topic title ends in Dev (SomePluginDev).
  • User support: Post installation, how to use type questions (and answers, if you have them) in the TWiki:Support web.

On-Site Pretesting

To test new Plugins on your installation before making them public, you may want to use one of these two approaches:

  • Method 1: Safely test on-the-fly by creating separate Production and Test branches in your live TWiki installation.
    • Duplicate the twiki/bin and twiki/lib directories for the Test version, and adjust the paths in the new lib/TWiki.cfg. The following directories are shared: twiki/data, twiki/templates and twiki/pub.
    • Test Plugins and other new features in the Test installation until you're satisfied.
      • ALERT! If you modify topics using the new features, live users will likely see unfamiliar new META tags showing up on their pages - to avoid this, create and edit test-only topics to try out new features.
    • Copy the modified files to the Production installation. You can update a TWiki installation live and users won't even notice.

  • Method 2: List the Plugin being tested in the DISABLEDPLUGINS variable in TWikiPreferences. Redefine the DISABLEDPLUGINS variable in the Sandbox web and do the testing there.

A Note on Plugin Performance

The performance of the system depends on the number of Plugins installed and on the Plugin implementation. Some Plugins impose no measurable performance decrease, some do. For example, outsidePREHandler is an expensive callback function, or a Plugin might use many Perl libraries that need to be initialized with each page view (unless you run mod_perl). It is recommended to measure the performance with and without a new Plugin. Example for Unix:
time wget -qO /dev/null https://wiki.ivoa.net/twiki/bin/view/TWiki/AbcPlugin

In case you need to install an "expensive" Plugin and you need its functionality only in one web you can place the Plugin topic into that web. TWiki will initialize the Plugin only if the Plugin topic is found (which won't be the case for other webs.)

Managing Plugins

When you finish installing a Plugin, you should be able to read the user instructions and go. In fact, some Plugins require additional settings or offer extra options that you have to select. Also, you may want to make a Plugin available only in certain webs, or temporarily disable it. And may want to list all available Plugins in certain topics. You can handle all of these management tasks with simple procedures.

Setting Preferences

Installed Plugins can be toggled on or off, site-wide or by web, through TWikiPreferences and individual WebPreferences:

  • All Plugin modules present in the lib/TWiki/Plugins directory are activated automatically unless disabled by the DISABLEDPLUGINS Preferences variable in TWikiPreferences. You can optionally list the installed Plugins in the INSTALLEDPLUGINS Preferences variable. This is useful to define the sequence of Plugin execution, or to specify other webs than the TWiki web for the Plugin topics. Settings in TWikiPreferences are:
    • Set INSTALLEDPLUGINS = DefaultPlugin, ...
    • Set DISABLEDPLUGINS = EmptyPlugin, ...

Plugin execution order in TWiki is determined by searching Plugin topics in a specific sequence: First, full web.topicname name, if specified in INSTALLEDPLUGINS; next, the TWiki web is searched; and finally, the current web.

Plugin-specific settings are done in individual Plugin topics. Two settings are standard for each Plugin:

  1. One line description, used to form the bullets describing the Plugins in the TextFormattingRules topic:
    • Set SHORTDESCRIPTION = Blah blah woof woof.
  2. Debug Plugin, output can be seen in data/debug.txt. Set to 0=off or 1=on:
    • Set DEBUG = 0
  • The settings can be retrieved as Preferences variables like %<pluginname>_<var>%, ex: %DEFAULTPLUGIN_SHORTDESCRIPTION% shows the description of the DefaultPlugin.

Listing Active Plugins

Plugin status variables let you list all active Plugins wherever needed. There are two list formats:

  • The %ACTIVATEDPLUGINS% variable lists activated Plugins by name. (This variable is displayed in TWikiPreferences for debugging use.)
  • The %PLUGINDESCRIPTIONS% variable displays a bullet list with a one-line description of each active Plugins. This variable is based on the %<plugin>_SHORTDESCRIPTION% Preferences variables of individual topics and is shown in TextFormattingRules.

DEMO: Automatically List Active Plugins Using Variables

Using %ACTIVATEDPLUGINS%:
On this TWiki site, the active Plugins are: SpreadSheetPlugin, BackupRestorePlugin, ColorPickerPlugin, CommentPlugin, DatePickerPlugin, EditTablePlugin, HeadlinesPlugin, InterwikiPlugin, JQueryPlugin, PreferencesPlugin, SetGetPlugin, SlideShowPlugin, SmiliesPlugin, TWikiSheetPlugin, TablePlugin, TagMePlugin, TinyMCEPlugin, TwistyPlugin, WatchlistPlugin, WysiwygPlugin.

Using %PLUGINDESCRIPTIONS%:
You can use any of these active TWiki Plugins:

  • SpreadSheetPlugin (2018-07-05, $Rev: 30478 (2018-07-16) $): Add spreadsheet calculation like "$SUM( $ABOVE() )" to TWiki tables or anywhere in topic text
  • BackupRestorePlugin (2021-03-19, $Rev: 30914 (2021-03-19) $): Administrator utility to backup, restore and upgrade a TWiki site
  • ColorPickerPlugin (2018-07-05, $Rev: 30442 (2018-07-16) $): Color picker, packaged for use in TWiki forms and TWiki applications
  • CommentPlugin (2018-07-05, $Rev: 30530 (2018-07-16) $): Quickly post comments to a page without an edit/preview/save cycle
  • DatePickerPlugin (2018-07-05, $Rev: 30446 (2018-07-16) $): Pop-up calendar with date picker, for use in TWiki forms, HTML forms and TWiki plugins
  • EditTablePlugin (2018-07-05, $Rev: 30448 (2018-07-16) $): Edit TWiki tables using edit fields, date pickers and drop down boxes
  • HeadlinesPlugin (2018-07-13, $Rev: 30560 (2018-07-16) $): Show headline news in TWiki pages based on RSS and ATOM news feeds from external sites
  • InterwikiPlugin (2018-07-05, $Rev: 30454 (2018-07-16) $): Write ExternalSite:Page to link to a page on an external site based on aliases defined in a rules topic
  • JQueryPlugin (2018-07-05, $Rev: 30456 (2018-07-16) $): jQuery JavaScript library for TWiki
  • PreferencesPlugin (2018-07-05, $Rev: 30528 (2018-07-16) $): Allows editing of preferences using fields predefined in a form
  • SetGetPlugin (2018-07-05, $Rev: 30472 (2018-07-16) $): Set and get variables and JSON objects in topics, optionally persistently across topic views
  • SlideShowPlugin (2018-07-05, $Rev: 30474 (2018-07-16) $): Create web based presentations based on topics with headings.
  • SmiliesPlugin (2018-07-05, $Rev: 30476 (2018-07-16) $): Render smilies as icons, like  :-) for smile or  :eek: for eek!
  • TWikiSheetPlugin (2018-07-15, $Rev: 30604 (2018-07-16) $): Add TWiki Sheet spreadsheet functionality to TWiki tables
  • TablePlugin (2018-07-05, $Rev: 30480 (2018-07-16) $): Control attributes of tables and sorting of table columns
  • TagMePlugin (2018-07-05, $Rev: 30482 (2018-07-16) $): Tag wiki content collectively or authoritatively to find content by keywords
  • TinyMCEPlugin (2021-06-09, $Rev: 31045 (2021-06-09) $): Integration of the Tiny MCE WYSIWYG Editor
  • TwistyPlugin (2018-07-06, $Rev: 30497 (2018-07-16) $): Twisty section JavaScript library to open/close content dynamically
  • WatchlistPlugin (2018-07-10, $Rev: 30536 (2018-07-16) $): Watch topics of interest and get notified of changes by e-mail
  • WysiwygPlugin (2018-07-06, $Rev: 30528 (2018-07-16) $): Translator framework for WYSIWYG editors

The TWiki Plugin API

The Application Programming Interface (API) for TWikiPlugins provides the specifications for hooking into the core TWiki code from your external Perl Plugin module. The Plugin API is new to the Production version of TWiki with the 01-Sep-2001 release.

Available Core Functions

The TWikiFuncModule (lib/TWiki/Func.pm) implements ALL official Plugin functions. Plugins should ONLY use functions published in this module.

ALERT! If you use functions not in Func.pm, you run the risk of creating security holes. Also, your Plugin will likely break and require updating when you upgrade to a new version of TWiki.

Predefined Hooks

In addition to TWiki core functions, Plugins can use predefined hooks, or call backs, listed in the lib/TWiki/Plugins/EmptyPlugin.pm module.

  • All but the initPlugin are disabled. To enable a call back, remove DISABLE_ from the function name.
  • For best performance, enable only the functions you really need. NOTE: outsidePREHandler and insidePREHandler are particularly expensive.

Most Plugins use either the commonTagsHandler or startRenderingHandler for rendering tasks:

  • commonTagsHandler: Use it to expand %XYZPLUGIN% and %XYZPLUGIN{...}% variables
  • startRenderingHandler: Use it for your own rendering rules or to overload TWiki's internal rendering like [[links]]

TWiki:Codev/StepByStepRenderingOrder helps you decide which rendering handler to use.

Hints on Writing Fast Plugins

  • Delay the Plugin initialization to the actual function which is handling the tag. This way all the expensive initialization is done only when needed.
  • For example, use an eval block like:
    eval { require IPC::Run }
    return "<font color=\"red\">SamplePlugin: Can't load required modules ($@)</font>" if $@;
  • You could return errors as strings to show what happened
  • You can use a flag to avoid running the initialization twice

Plugin Version Detection

To eliminate the incompatibility problems bound to arise from active open Plugin development, a Plugin versioning system and an API GetVersion detection routine are provided for automatic compatibility checking.

  • All modules require a $VERSION='0.000' variable, beginning at 1.000.

  • The initPlugin handler should check all dependencies and return TRUE if the initialization is OK or FALSE if something went wrong.
    • The Plugin initialization code does not register a Plugin that returns FALSE (or that has no initPlugin handler).

Creating Plugins

With a reasonable knowledge of the Perl scripting language, you can create new Plugins or modify and extend existing ones. Basic plug-in architecture uses an Application Programming Interface (API), a set of software instructions that allow external code to interact with the main program. The TWiki Plugin API Plugins by providing a programming interface for TWiki.

The DefaultPlugin Alternative

  • DefaultPlugin can handle some outdated TWiki variables, found, for example, in sites recently updated from an old version. Settings are in DefaultPlugin topic. You can also add your own simple custom processing rules here, though in all but very simple cases, writing a new Plugin is preferable.

Anatomy of a Plugin

A basic TWiki Plugin consists of two elements:

  • a Perl module, ex: MyFirstPlugin.pm
  • a documentation topic, ex: MyFirstPlugin.txt

The Perl module can be a block of code that connects with TWiki alone, or it can include other elements, like other Perl modules (including other Plugins), graphics, TWiki templates, external applications (ex: a Java applet), or just about anything else it can call. In particular, files that should be web-accessible (graphics, Java applets ...) are best placed as attachments of the MyFirstPlugin topic. Other needed Perl code is best placed in a lib/TWiki/Plugins/MyFirstPlugin/ directory.

The Plugin API handles the details of connecting your Perl module with main TWiki code. When you're familiar with the Plugin API, you're ready to develop Plugins.

Creating the Perl Module

Copy file lib/TWiki/Plugins/EmptyPlugin.pm to <name>Plugin.pm. The EmptyPlugin.pm module contains mostly empty functions, so it does nothing, but it's ready to be used. Customize it. Refer to the Plugin API specs for more information.

If your Plugin uses its own modules and objects, you must include the name of the Plugin in the package name. For example, write Package MyFirstPlugin::Attrs; instead of just Package Attrs;. Then call it using:

  use TWiki::Plugins::MyFirstPlugin::Attrs;
  $var = MyFirstPlugin::Attrs->new();

Writing the Documentation Topic

The Plugin documentation topic contains usage instructions and version details. It serves the Plugin files as FileAttachments for downloading. (The doc topic is also included in the distribution package.) To create a documentation topic:

  1. Copy the Plugin topic template from TWiki.org. To copy the text, go to TWiki:Plugins/PluginPackage and:
    • enter the Plugin name in the "How to Create a Plugin" section
    • click Create
    • select all in the Edit box & copy
    • Cancel the edit
    • go back to your site to the TWiki web
    • In the GoBox enter your Plugin name, for example MyFirstPlugin, press enter and create the new topic
    • paste & save new Plugin topic on your site
  2. Customize your Plugin topic.
    • In case you plan to publish your Plugin at TWiki.org, use Interwiki names for author names, like TWiki:Main/TWikiGuest.
  3. Save your topic, for use in packaging and publishing your Plugin.

OUTLINE: Doc Topic Contents
Check the Plugins web on TWiki.org for the latest Plugin doc topic template. Here's a quick overview of what's covered:

Syntax Rules: <Describe any special text formatting that will be rendered.>"

Example: <Include an example of the Plugin in action. Possibly include a static HTML version of the example to compare if the installation was a success!>"

Plugin Settings: <Description and settings for custom Plugin %VARIABLES%, and those required by TWiki.>"

  • Plugins Preferences <If user settings are needed, explain... Entering values works exactly like TWikiPreferences and WebPreferences: six (6) spaces and then:>"
    • Set <EXAMPLE = value added>

Plugin Installation Instructions: <Step-by-step set-up guide, user help, whatever it takes to install and run, goes here.>"

Plugin Info: <Version, credits, history, requirements - entered in a form, displayed as a table. Both are automatically generated when you create or edit a page in the TWiki:Plugins web.>"

Packaging for Distribution

A minimum Plugin release consists of a Perl module with a WikiName that ends in Plugin, ex: MyFirstPlugin.pm, and a documentation page with the same name(MyFirstPlugin.txt).

  1. Distribute the Plugin files in a directory structure that mirrors TWiki. If your Plugin uses additional files, include them ALL:
    • lib/TWiki/Plugins/MyFirstPlugin.pm
    • data/TWiki/MyFirstPlugin.txt
    • pub/TWiki/MyFirstPlugin/uparrow.gif [a required graphic]
  2. Create a zip archive with the Plugin name (MyFirstPlugin.zip) and add the entire directory structure from Step 1. The archive should look like this:
    • lib/TWiki/Plugins/MyFirstPlugin.pm
    • data/TWiki/MyFirstPlugin.txt
    • pub/TWiki/MyFirstPlugin/uparrow.gif

Publishing for Public Use

You can release your tested, packaged Plugin to the TWiki community through the TWiki:Plugins web. All Plugins submitted to TWiki.org are available for download and further development in TWiki:Plugins/PluginPackage. Publish your Plugin in these steps:

  1. Post the Plugin documentation topic in the TWiki:Plugins/PluginPackage:
    • enter the Plugin name in the "How to Create a Plugin" section, for example MyFirstPlugin
    • paste in the topic text from Creating Plugin Documentation and save
  2. Attach the distribution zip file to the topic, ex: MyFirstPlugin.zip
  3. Link from the doc page to a new, blank page named after the Plugin, and ending in Dev, ex: MyFirstPluginDev. This is the discussion page for future development. (User support for Plugins is handled in TWiki:Support.)
  4. Put the Plugin into the CVS repository, see TWiki:Plugins/ReadmeFirst (optional)

Thank you very much for sharing your Plugin with the TWiki community smile

Recommended Storage of Plugin Data

Plugins sometimes need to store data. This can be Plugin internal data like cache data, or generated data for the browser like images. The following is a recommendation where to store the data.

Where to store Plugin Internal Data

In case the Plugin generates data just for internal use, or data which is not specific to a topic, store it in the Plugin's attachment directory.

  • The Plugin's attachment directory is pubdir/Installweb/FooBarPlugin
    • Installweb refers to the name of the web where the Plugin is installed
  • The Plugin's attachment URL is %PUBURL%/Installweb/FooBarPlugin
  • The filename should start with an underscore, followed by an identifier, e.g. _any_name.ext
    • The leading underscore avoids a nameclash with files attached to the Plugin topic
    • Use only alphanumeric characters, underscores and periods to avoid platform dependency issues and URL issues
    • Do not use subdirectories (rename and delete would fail)
  • Use Plugin API functions documented in TWikiFuncModule to ensure portability:
    • Use getPubDir() to get the attachment root directory
    • Use getUrlHost() and getPubUrlPath() to build the URL in case you create content for the browser
    • Use $installWeb to get the name of the web where the Plugin is installed
    • Create the web directory and topic attachment directory if needed
  • Hint: Package the Plugin at least with one file attachment. This ensures that the attachment directory already exists

Where to Store Data for Topics using the Plugin

In case the Plugin generates data which is specific to a topic, store it in the topic's attachment directory.

  • The topic's attachment directory is pubdir/Webname/TopicName
  • The topic's attachment URL is %PUBURL%/Webname/TopicName
  • The filename should start with an underscore, followed by the Plugin name, an underscore and an identifier, e.g. _FooBarPlugin_any_name.ext
    • The leading underscore avoids a nameclash with files attached to the same topic
    • Use only alphanumeric characters, underscores and periods to avoid platform dependency issues and URL issues
    • Do not use subdirectories (rename and delete would fail)
  • Use Plugin API functions documented in TWikiFuncModule to ensure portability:
    • Use getPubDir() to get the attachment root directory
    • Use getUrlHost() and getPubUrlPath() to build the URL in case you create content for the browser

Example code to build the file name:

sub _make_filename
{
    my ( $web, $topic, $name ) = @_;

    # Create web directory "pub/$web" if needed
    my $dir = TWiki::Func::getPubDir() . "/$web";
    unless( -e "$dir" ) {
        umask( 002 );
        mkdir( $dir, 0775 );
    }
    # Create topic directory "pub/$web/$topic" if needed
    $dir .= "/$topic";
    unless( -e "$dir" ) {
        umask( 002 );
        mkdir( $dir, 0775 );
    }
    return "$dir/_FooBarPlugin_$name";
}

-- TWiki:Main/PeterThoeny - 11 Dec 2003
-- TWiki:Main/AndreaSterbini - 29 May 2001
-- TWiki:Main/MikeMannix - 03 Dec 2001

>
>

TWiki Plugins

Plug-in enhanced feature add-ons, with a Plugin API for developers

Overview

You can add Plugins to extend TWiki's functionality, without altering the core program code. A plug-in approach lets you:

  • add virtually unlimited features while keeping the main TWiki code compact and efficient;
  • heavily customize an installation and still do clean updates to new versions of TWiki;
  • rapidly develop new TWiki functions in Perl using the Plugin API.

Everything to do with TWiki Plugins - demos, new releases, downloads, development, general discussion - is available at TWiki.org, in the TWiki:Plugins web.

Preinstalled Plugins

TWiki comes with a set of Plugins as part of the standard installation.

  • DefaultPlugin: Optionally handles some legacy variables from older versions of TWiki. You can control this option from TWikiPreferences. (Perl programmers can also add rules for simple custom processing.)
  • EmptyPlugin: Is a fully functional module, minus active code; it does nothing and serves as a template for new Plugin development.
  • InterwikiPlugin: Use it for shorthand linking to remote sites, ex: TWiki:Plugins expands to TWiki:Plugins on TWiki.org. You can edit the predefined set of of Wiki-related sites, and add your own.
  • EditTablePlugin: Edit TWiki tables using edit fields, date pickers and drop down boxes
  • RenderListPlugin: %RENDERLISTPLUGIN_SHORTDESCRIPTION%
  • SlideShowPlugin: Create web based presentations based on topics with headings.
  • SmiliesPlugin: Render smilies as icons, like  :-) for smile or  :eek: for eek!
  • SpreadSheetPlugin: Add spreadsheet calculation like "$SUM( $ABOVE() )" to TWiki tables or anywhere in topic text
  • TablePlugin: Control attributes of tables and sorting of table columns

Installing Plugins

Each TWikiPlugin comes with full documentation: step-by-step installation instructions, a detailed description of any special requirements, version details, and a working example for testing.

Most Plugins can be installed in three easy steps, with no programming skills required:

  1. Download the zip file containing the Plugin, documentation, and any other required files, from TWiki:Plugins.
  2. Distribute the files to their proper locations - unzip the zip archive in your TWiki installation directory - if have a standard TWiki installation, this will distribute automatically. Otherwise, place the files according to the directory paths listed on the Plugin top in TWiki:Plugins.
  3. Check the demo example on the Plugin topic: if it's working, the installation was fine!

Special Requests: Some Plugins need certain Perl modules to be preinstalled on the host system. Plugins may also use other resources, like graphics, other modules, applications, templates. In these cases, detailed instructions are in the Plugin documentation.

Each Plugin has a standard release page, located in the TWiki:Plugins web at TWiki.org. In addition to the documentation topic (SomePlugin), there's a separate development page.

  • Doc page: Read all available info about the Plugin; download the attached distribution files.
  • Dev page: Post feature requests, bug reports and general dev comments; topic title ends in Dev (SomePluginDev).
  • User support: Post installation, how to use type questions (and answers, if you have them) in the TWiki:Support web.

On-Site Pretesting

To test new Plugins on your installation before making them public, you may want to use one of these two approaches:

  • Method 1: Safely test on-the-fly by creating separate Production and Test branches in your live TWiki installation.
    • Duplicate the twiki/bin and twiki/lib directories for the Test version, and adjust the paths in the new lib/TWiki.cfg. The following directories are shared: twiki/data, twiki/templates and twiki/pub.
    • Test Plugins and other new features in the Test installation until you're satisfied.
      • ALERT! If you modify topics using the new features, live users will likely see unfamiliar new META tags showing up on their pages - to avoid this, create and edit test-only topics to try out new features.
    • Copy the modified files to the Production installation. You can update a TWiki installation live and users won't even notice.

  • Method 2: List the Plugin being tested in the DISABLEDPLUGINS variable in TWikiPreferences. Redefine the DISABLEDPLUGINS variable in the Sandbox web and do the testing there.

Checking that Plugins are Working on a Live Server

InstalledPlugins shows which Plugins are: 1) installed, 2) loading properly and 3) what TWiki:Codev.PluginHandlers they invoke. Any failures are shown in the Errors section.

A Note on Plugin Performance

The performance of the system depends on the number of Plugins installed and on the Plugin implementation. Some Plugins impose no measurable performance decrease, some do. For example, outsidePREHandler is an expensive callback function, or a Plugin might use many Perl libraries that need to be initialized with each page view (unless you run mod_perl). It is recommended to measure the performance with and without a new Plugin. Example for Unix:
time wget -qO /dev/null https://wiki.ivoa.net/twiki/bin/view/TWiki/AbcPlugin

In case you need to install an "expensive" Plugin and you need its functionality only in one web you can place the Plugin topic into that web. TWiki will initialize the Plugin only if the Plugin topic is found (which won't be the case for other webs.)

Managing Plugins

When you finish installing a Plugin, you should be able to read the user instructions and go. In fact, some Plugins require additional settings or offer extra options that you have to select. Also, you may want to make a Plugin available only in certain webs, or temporarily disable it. And may want to list all available Plugins in certain topics. You can handle all of these management tasks with simple procedures.

Setting Preferences

Installed Plugins can be toggled on or off, site-wide or by web, through TWikiPreferences and individual WebPreferences:

  • All Plugin modules present in the lib/TWiki/Plugins directory are activated automatically unless disabled by the DISABLEDPLUGINS Preferences variable in TWikiPreferences. You can optionally list the installed Plugins in the INSTALLEDPLUGINS Preferences variable. This is useful to define the sequence of Plugin execution, or to specify other webs than the TWiki web for the Plugin topics. Settings in TWikiPreferences are:
    • Set INSTALLEDPLUGINS = DefaultPlugin, ...
    • Set DISABLEDPLUGINS = EmptyPlugin, ...

Plugin execution order in TWiki is determined by searching Plugin topics in a specific sequence: First, full web.topicname name, if specified in INSTALLEDPLUGINS; next, the TWiki web is searched; and finally, the current web.

Plugin-specific settings are done in individual Plugin topics. Two settings are standard for each Plugin:

  1. One line description, used to form the bullets describing the Plugins in the TextFormattingRules topic:
    • Set SHORTDESCRIPTION = Blah blah woof woof.
  2. Debug Plugin, output can be seen in data/debug.txt. Set to 0=off or 1=on:
    • Set DEBUG = 0
  • The settings can be retrieved as Preferences variables like %<pluginname>_<var>%, ex: %DEFAULTPLUGIN_SHORTDESCRIPTION% shows the description of the DefaultPlugin.

Listing Active Plugins

Plugin status variables let you list all active Plugins wherever needed. There are two list formats:

  • The %ACTIVATEDPLUGINS% variable lists activated Plugins by name. (This variable is displayed in TWikiPreferences for debugging use.)
  • The %PLUGINDESCRIPTIONS% variable displays a bullet list with a one-line description of each active Plugins. This variable is based on the %<plugin>_SHORTDESCRIPTION% Preferences variables of individual topics and is shown in TextFormattingRules.

DEMO: Automatically List Active Plugins Using Variables

Using %ACTIVATEDPLUGINS%:
On this TWiki site, the active Plugins are: SpreadSheetPlugin, BackupRestorePlugin, ColorPickerPlugin, CommentPlugin, DatePickerPlugin, EditTablePlugin, HeadlinesPlugin, InterwikiPlugin, JQueryPlugin, PreferencesPlugin, SetGetPlugin, SlideShowPlugin, SmiliesPlugin, TWikiSheetPlugin, TablePlugin, TagMePlugin, TinyMCEPlugin, TwistyPlugin, WatchlistPlugin, WysiwygPlugin.

Using %PLUGINDESCRIPTIONS%:
You can use any of these active TWiki Plugins:

  • SpreadSheetPlugin (2018-07-05, $Rev: 30478 (2018-07-16) $): Add spreadsheet calculation like "$SUM( $ABOVE() )" to TWiki tables or anywhere in topic text
  • BackupRestorePlugin (2021-03-19, $Rev: 30914 (2021-03-19) $): Administrator utility to backup, restore and upgrade a TWiki site
  • ColorPickerPlugin (2018-07-05, $Rev: 30442 (2018-07-16) $): Color picker, packaged for use in TWiki forms and TWiki applications
  • CommentPlugin (2018-07-05, $Rev: 30530 (2018-07-16) $): Quickly post comments to a page without an edit/preview/save cycle
  • DatePickerPlugin (2018-07-05, $Rev: 30446 (2018-07-16) $): Pop-up calendar with date picker, for use in TWiki forms, HTML forms and TWiki plugins
  • EditTablePlugin (2018-07-05, $Rev: 30448 (2018-07-16) $): Edit TWiki tables using edit fields, date pickers and drop down boxes
  • HeadlinesPlugin (2018-07-13, $Rev: 30560 (2018-07-16) $): Show headline news in TWiki pages based on RSS and ATOM news feeds from external sites
  • InterwikiPlugin (2018-07-05, $Rev: 30454 (2018-07-16) $): Write ExternalSite:Page to link to a page on an external site based on aliases defined in a rules topic
  • JQueryPlugin (2018-07-05, $Rev: 30456 (2018-07-16) $): jQuery JavaScript library for TWiki
  • PreferencesPlugin (2018-07-05, $Rev: 30528 (2018-07-16) $): Allows editing of preferences using fields predefined in a form
  • SetGetPlugin (2018-07-05, $Rev: 30472 (2018-07-16) $): Set and get variables and JSON objects in topics, optionally persistently across topic views
  • SlideShowPlugin (2018-07-05, $Rev: 30474 (2018-07-16) $): Create web based presentations based on topics with headings.
  • SmiliesPlugin (2018-07-05, $Rev: 30476 (2018-07-16) $): Render smilies as icons, like  :-) for smile or  :eek: for eek!
  • TWikiSheetPlugin (2018-07-15, $Rev: 30604 (2018-07-16) $): Add TWiki Sheet spreadsheet functionality to TWiki tables
  • TablePlugin (2018-07-05, $Rev: 30480 (2018-07-16) $): Control attributes of tables and sorting of table columns
  • TagMePlugin (2018-07-05, $Rev: 30482 (2018-07-16) $): Tag wiki content collectively or authoritatively to find content by keywords
  • TinyMCEPlugin (2021-06-09, $Rev: 31045 (2021-06-09) $): Integration of the Tiny MCE WYSIWYG Editor
  • TwistyPlugin (2018-07-06, $Rev: 30497 (2018-07-16) $): Twisty section JavaScript library to open/close content dynamically
  • WatchlistPlugin (2018-07-10, $Rev: 30536 (2018-07-16) $): Watch topics of interest and get notified of changes by e-mail
  • WysiwygPlugin (2018-07-06, $Rev: 30528 (2018-07-16) $): Translator framework for WYSIWYG editors

The TWiki Plugin API

The Application Programming Interface (API) for TWikiPlugins provides the specifications for hooking into the core TWiki code from your external Perl Plugin module. The Plugin API is new to the Production version of TWiki with the 01-Sep-2001 release.

Available Core Functions

The TWikiFuncModule (lib/TWiki/Func.pm) implements ALL official Plugin functions. Plugins should ONLY use functions published in this module.

ALERT! If you use functions not in Func.pm, you run the risk of creating security holes. Also, your Plugin will likely break and require updating when you upgrade to a new version of TWiki.

Predefined Hooks

In addition to TWiki core functions, Plugins can use predefined hooks, or call backs, listed in the lib/TWiki/Plugins/EmptyPlugin.pm module.

  • All but the initPlugin are disabled. To enable a call back, remove DISABLE_ from the function name.
  • For best performance, enable only the functions you really need. NOTE: outsidePREHandler and insidePREHandler are particularly expensive.

Most Plugins use either the commonTagsHandler or startRenderingHandler for rendering tasks:

  • commonTagsHandler: Use it to expand %XYZPLUGIN% and %XYZPLUGIN{...}% variables
  • startRenderingHandler: Use it for your own rendering rules or to overload TWiki's internal rendering like [[links]]

TWiki:Codev/StepByStepRenderingOrder helps you decide which rendering handler to use.

Hints on Writing Fast Plugins

  • Delay the Plugin initialization to the actual function which is handling the tag. This way all the expensive initialization is done only when needed.
  • For example, use an eval block like:
    eval { require IPC::Run }
    return "<font color=\"red\">SamplePlugin: Can't load required modules ($@)</font>" if $@;
  • You could return errors as strings to show what happened
  • You can use a flag to avoid running the initialization twice

Plugin Version Detection

To eliminate the incompatibility problems bound to arise from active open Plugin development, a Plugin versioning system and an API GetVersion detection routine are provided for automatic compatibility checking.

  • All modules require a $VERSION='0.000' variable, beginning at 1.000.

  • The initPlugin handler should check all dependencies and return TRUE if the initialization is OK or FALSE if something went wrong.
    • The Plugin initialization code does not register a Plugin that returns FALSE (or that has no initPlugin handler).

Creating Plugins

With a reasonable knowledge of the Perl scripting language, you can create new Plugins or modify and extend existing ones. Basic plug-in architecture uses an Application Programming Interface (API), a set of software instructions that allow external code to interact with the main program. The TWiki Plugin API Plugins by providing a programming interface for TWiki.

The DefaultPlugin Alternative

  • DefaultPlugin can handle some outdated TWiki variables, found, for example, in sites recently updated from an old version. Settings are in DefaultPlugin topic. You can also add your own simple custom processing rules here, though in all but very simple cases, writing a new Plugin is preferable.

Anatomy of a Plugin

A basic TWiki Plugin consists of two elements:

  • a Perl module, ex: MyFirstPlugin.pm
  • a documentation topic, ex: MyFirstPlugin.txt

The Perl module can be a block of code that connects with TWiki alone, or it can include other elements, like other Perl modules (including other Plugins), graphics, TWiki templates, external applications (ex: a Java applet), or just about anything else it can call. In particular, files that should be web-accessible (graphics, Java applets ...) are best placed as attachments of the MyFirstPlugin topic. Other needed Perl code is best placed in a lib/TWiki/Plugins/MyFirstPlugin/ directory.

The Plugin API handles the details of connecting your Perl module with main TWiki code. When you're familiar with the Plugin API, you're ready to develop Plugins.

Creating the Perl Module

Copy file lib/TWiki/Plugins/EmptyPlugin.pm to <name>Plugin.pm. The EmptyPlugin.pm module contains mostly empty functions, so it does nothing, but it's ready to be used. Customize it. Refer to the Plugin API specs for more information.

If your Plugin uses its own modules and objects, you must include the name of the Plugin in the package name. For example, write Package MyFirstPlugin::Attrs; instead of just Package Attrs;. Then call it using:

  use TWiki::Plugins::MyFirstPlugin::Attrs;
  $var = MyFirstPlugin::Attrs->new();

Writing the Documentation Topic

The Plugin documentation topic contains usage instructions and version details. It serves the Plugin files as FileAttachments for downloading. (The doc topic is also included in the distribution package.) To create a documentation topic:

  1. Copy the Plugin topic template from TWiki.org. To copy the text, go to TWiki:Plugins/PluginPackage and:
    • enter the Plugin name in the "How to Create a Plugin" section
    • click Create
    • select all in the Edit box & copy
    • Cancel the edit
    • go back to your site to the TWiki web
    • In the GoBox enter your Plugin name, for example MyFirstPlugin, press enter and create the new topic
    • paste & save new Plugin topic on your site
  2. Customize your Plugin topic.
    • In case you plan to publish your Plugin at TWiki.org, use Interwiki names for author names, like TWiki:Main/TWikiGuest.
  3. Save your topic, for use in packaging and publishing your Plugin.

OUTLINE: Doc Topic Contents
Check the Plugins web on TWiki.org for the latest Plugin doc topic template. Here's a quick overview of what's covered:

Syntax Rules: <Describe any special text formatting that will be rendered.>"

Example: <Include an example of the Plugin in action. Possibly include a static HTML version of the example to compare if the installation was a success!>"

Plugin Settings: <Description and settings for custom Plugin %VARIABLES%, and those required by TWiki.>"

  • Plugins Preferences <If user settings are needed, explain... Entering values works exactly like TWikiPreferences and WebPreferences: six (6) spaces and then:>"
    • Set <EXAMPLE = value added>

Plugin Installation Instructions: <Step-by-step set-up guide, user help, whatever it takes to install and run, goes here.>"

Plugin Info: <Version, credits, history, requirements - entered in a form, displayed as a table. Both are automatically generated when you create or edit a page in the TWiki:Plugins web.>"

Packaging for Distribution

A minimum Plugin release consists of a Perl module with a WikiName that ends in Plugin, ex: MyFirstPlugin.pm, and a documentation page with the same name(MyFirstPlugin.txt).

  1. Distribute the Plugin files in a directory structure that mirrors TWiki. If your Plugin uses additional files, include them ALL:
    • lib/TWiki/Plugins/MyFirstPlugin.pm
    • data/TWiki/MyFirstPlugin.txt
    • pub/TWiki/MyFirstPlugin/uparrow.gif [a required graphic]
  2. Create a zip archive with the Plugin name (MyFirstPlugin.zip) and add the entire directory structure from Step 1. The archive should look like this:
    • lib/TWiki/Plugins/MyFirstPlugin.pm
    • data/TWiki/MyFirstPlugin.txt
    • pub/TWiki/MyFirstPlugin/uparrow.gif

Publishing for Public Use

You can release your tested, packaged Plugin to the TWiki community through the TWiki:Plugins web. All Plugins submitted to TWiki.org are available for download and further development in TWiki:Plugins/PluginPackage. Publish your Plugin in these steps:

  1. Post the Plugin documentation topic in the TWiki:Plugins/PluginPackage:
    • enter the Plugin name in the "How to Create a Plugin" section, for example MyFirstPlugin
    • paste in the topic text from Creating Plugin Documentation and save
  2. Attach the distribution zip file to the topic, ex: MyFirstPlugin.zip
  3. Link from the doc page to a new, blank page named after the Plugin, and ending in Dev, ex: MyFirstPluginDev. This is the discussion page for future development. (User support for Plugins is handled in TWiki:Support.)
  4. Put the Plugin into the CVS repository, see TWiki:Plugins/ReadmeFirst (optional)

Thank you very much for sharing your Plugin with the TWiki community smile

Recommended Storage of Plugin Data

Plugins sometimes need to store data. This can be Plugin internal data like cache data, or generated data for the browser like images. The following is a recommendation where to store the data.

Where to store Plugin Internal Data

In case the Plugin generates data just for internal use, or data which is not specific to a topic, store it in the Plugin's attachment directory.

  • The Plugin's attachment directory is pubdir/Installweb/FooBarPlugin
    • Installweb refers to the name of the web where the Plugin is installed
  • The Plugin's attachment URL is %PUBURL%/Installweb/FooBarPlugin
  • The filename should start with an underscore, followed by an identifier, e.g. _any_name.ext
    • The leading underscore avoids a nameclash with files attached to the Plugin topic
    • Use only alphanumeric characters, underscores and periods to avoid platform dependency issues and URL issues
    • Do not use subdirectories (rename and delete would fail)
  • Use Plugin API functions documented in TWikiFuncModule to ensure portability:
    • Use getPubDir() to get the attachment root directory
    • Use getUrlHost() and getPubUrlPath() to build the URL in case you create content for the browser
    • Use $installWeb to get the name of the web where the Plugin is installed
    • Create the web directory and topic attachment directory if needed
  • Hint: Package the Plugin at least with one file attachment. This ensures that the attachment directory already exists

Where to Store Data for Topics using the Plugin

In case the Plugin generates data which is specific to a topic, store it in the topic's attachment directory.

  • The topic's attachment directory is pubdir/Webname/TopicName
  • The topic's attachment URL is %PUBURL%/Webname/TopicName
  • The filename should start with an underscore, followed by the Plugin name, an underscore and an identifier, e.g. _FooBarPlugin_any_name.ext
    • The leading underscore avoids a nameclash with files attached to the same topic
    • Use only alphanumeric characters, underscores and periods to avoid platform dependency issues and URL issues
    • Do not use subdirectories (rename and delete would fail)
  • Use Plugin API functions documented in TWikiFuncModule to ensure portability:
    • Use getPubDir() to get the attachment root directory
    • Use getUrlHost() and getPubUrlPath() to build the URL in case you create content for the browser

Example code to build the file name:

sub _make_filename
{
    my ( $web, $topic, $name ) = @_;

    # Create web directory "pub/$web" if needed
    my $dir = TWiki::Func::getPubDir() . "/$web";
    unless( -e "$dir" ) {
        umask( 002 );
        mkdir( $dir, 0775 );
    }
    # Create topic directory "pub/$web/$topic" if needed
    $dir .= "/$topic";
    unless( -e "$dir" ) {
        umask( 002 );
        mkdir( $dir, 0775 );
    }
    return "$dir/_FooBarPlugin_$name";
}
Added:
>
>
-- TWiki:Main/PeterThoeny - 18 May 2004
-- TWiki:Main/AndreaSterbini - 29 May 2001
-- TWiki:Main/MikeMannix - 03 Dec 2001
 

Revision 262003-12-15 - PeterThoeny

 

TWiki Plugins

Plug-in enhanced feature add-ons, with a Plugin API for developers

Overview

You can add Plugins to extend TWiki's functionality, without altering the core program code. A plug-in approach lets you:

  • add virtually unlimited features while keeping the main TWiki code compact and efficient;
  • heavily customize an installation and still do clean updates to new versions of TWiki;
  • rapidly develop new TWiki functions in Perl using the Plugin API.

Everything to do with TWiki Plugins - demos, new releases, downloads, development, general discussion - is available at TWiki.org, in the TWiki:Plugins web.

Preinstalled Plugins

TWiki comes with a set of Plugins as part of the standard installation.

  • DefaultPlugin: Optionally handles some legacy variables from older versions of TWiki. You can control this option from TWikiPreferences. (Perl programmers can also add rules for simple custom processing.)
  • EmptyPlugin: Is a fully functional module, minus active code; it does nothing and serves as a template for new Plugin development.
  • InterwikiPlugin: Use it for shorthand linking to remote sites, ex: TWiki:Plugins expands to TWiki:Plugins on TWiki.org. You can edit the predefined set of of Wiki-related sites, and add your own.
  • EditTablePlugin: Edit TWiki tables using edit fields, date pickers and drop down boxes
  • RenderListPlugin: %RENDERLISTPLUGIN_SHORTDESCRIPTION%
  • SlideShowPlugin: Create web based presentations based on topics with headings.
  • SmiliesPlugin: Render smilies as icons, like  :-) for smile or  :eek: for eek!
  • SpreadSheetPlugin: Add spreadsheet calculation like "$SUM( $ABOVE() )" to TWiki tables or anywhere in topic text
  • TablePlugin: Control attributes of tables and sorting of table columns

Installing Plugins

Each TWikiPlugin comes with full documentation: step-by-step installation instructions, a detailed description of any special requirements, version details, and a working example for testing.

Most Plugins can be installed in three easy steps, with no programming skills required:

  1. Download the zip file containing the Plugin, documentation, and any other required files, from TWiki:Plugins.
  2. Distribute the files to their proper locations - unzip the zip archive in your TWiki installation directory - if have a standard TWiki installation, this will distribute automatically. Otherwise, place the files according to the directory paths listed on the Plugin top in TWiki:Plugins.
  3. Check the demo example on the Plugin topic: if it's working, the installation was fine!

Special Requests: Some Plugins need certain Perl modules to be preinstalled on the host system. Plugins may also use other resources, like graphics, other modules, applications, templates. In these cases, detailed instructions are in the Plugin documentation.

Each Plugin has a standard release page, located in the TWiki:Plugins web at TWiki.org. In addition to the documentation topic (SomePlugin), there's a separate development page.

  • Doc page: Read all available info about the Plugin; download the attached distribution files.
  • Dev page: Post feature requests, bug reports and general dev comments; topic title ends in Dev (SomePluginDev).
  • User support: Post installation, how to use type questions (and answers, if you have them) in the TWiki:Support web.

On-Site Pretesting

To test new Plugins on your installation before making them public, you may want to use one of these two approaches:

  • Method 1: Safely test on-the-fly by creating separate Production and Test branches in your live TWiki installation.
    • Duplicate the twiki/bin and twiki/lib directories for the Test version, and adjust the paths in the new lib/TWiki.cfg. The following directories are shared: twiki/data, twiki/templates and twiki/pub.
    • Test Plugins and other new features in the Test installation until you're satisfied.
      • ALERT! If you modify topics using the new features, live users will likely see unfamiliar new META tags showing up on their pages - to avoid this, create and edit test-only topics to try out new features.
    • Copy the modified files to the Production installation. You can update a TWiki installation live and users won't even notice.

  • Method 2: List the Plugin being tested in the DISABLEDPLUGINS variable in TWikiPreferences. Redefine the DISABLEDPLUGINS variable in the Sandbox web and do the testing there.

A Note on Plugin Performance

The performance of the system depends on the number of Plugins installed and on the Plugin implementation. Some Plugins impose no measurable performance decrease, some do. For example, outsidePREHandler is an expensive callback function, or a Plugin might use many Perl libraries that need to be initialized with each page view (unless you run mod_perl). It is recommended to measure the performance with and without a new Plugin. Example for Unix:
time wget -qO /dev/null https://wiki.ivoa.net/twiki/bin/view/TWiki/AbcPlugin

In case you need to install an "expensive" Plugin and you need its functionality only in one web you can place the Plugin topic into that web. TWiki will initialize the Plugin only if the Plugin topic is found (which won't be the case for other webs.)

Managing Plugins

When you finish installing a Plugin, you should be able to read the user instructions and go. In fact, some Plugins require additional settings or offer extra options that you have to select. Also, you may want to make a Plugin available only in certain webs, or temporarily disable it. And may want to list all available Plugins in certain topics. You can handle all of these management tasks with simple procedures.

Setting Preferences

Installed Plugins can be toggled on or off, site-wide or by web, through TWikiPreferences and individual WebPreferences:

  • All Plugin modules present in the lib/TWiki/Plugins directory are activated automatically unless disabled by the DISABLEDPLUGINS Preferences variable in TWikiPreferences. You can optionally list the installed Plugins in the INSTALLEDPLUGINS Preferences variable. This is useful to define the sequence of Plugin execution, or to specify other webs than the TWiki web for the Plugin topics. Settings in TWikiPreferences are:
    • Set INSTALLEDPLUGINS = DefaultPlugin, ...
    • Set DISABLEDPLUGINS = EmptyPlugin, ...

Plugin execution order in TWiki is determined by searching Plugin topics in a specific sequence: First, full web.topicname name, if specified in INSTALLEDPLUGINS; next, the TWiki web is searched; and finally, the current web.

Plugin-specific settings are done in individual Plugin topics. Two settings are standard for each Plugin:

  1. One line description, used to form the bullets describing the Plugins in the TextFormattingRules topic:
    • Set SHORTDESCRIPTION = Blah blah woof woof.
  2. Debug Plugin, output can be seen in data/debug.txt. Set to 0=off or 1=on:
    • Set DEBUG = 0
  • The settings can be retrieved as Preferences variables like %<pluginname>_<var>%, ex: %DEFAULTPLUGIN_SHORTDESCRIPTION% shows the description of the DefaultPlugin.

Listing Active Plugins

Plugin status variables let you list all active Plugins wherever needed. There are two list formats:

  • The %ACTIVATEDPLUGINS% variable lists activated Plugins by name. (This variable is displayed in TWikiPreferences for debugging use.)
  • The %PLUGINDESCRIPTIONS% variable displays a bullet list with a one-line description of each active Plugins. This variable is based on the %<plugin>_SHORTDESCRIPTION% Preferences variables of individual topics and is shown in TextFormattingRules.

DEMO: Automatically List Active Plugins Using Variables

Using %ACTIVATEDPLUGINS%:
On this TWiki site, the active Plugins are: SpreadSheetPlugin, BackupRestorePlugin, ColorPickerPlugin, CommentPlugin, DatePickerPlugin, EditTablePlugin, HeadlinesPlugin, InterwikiPlugin, JQueryPlugin, PreferencesPlugin, SetGetPlugin, SlideShowPlugin, SmiliesPlugin, TWikiSheetPlugin, TablePlugin, TagMePlugin, TinyMCEPlugin, TwistyPlugin, WatchlistPlugin, WysiwygPlugin.

Using %PLUGINDESCRIPTIONS%:
You can use any of these active TWiki Plugins:

  • SpreadSheetPlugin (2018-07-05, $Rev: 30478 (2018-07-16) $): Add spreadsheet calculation like "$SUM( $ABOVE() )" to TWiki tables or anywhere in topic text
  • BackupRestorePlugin (2021-03-19, $Rev: 30914 (2021-03-19) $): Administrator utility to backup, restore and upgrade a TWiki site
  • ColorPickerPlugin (2018-07-05, $Rev: 30442 (2018-07-16) $): Color picker, packaged for use in TWiki forms and TWiki applications
  • CommentPlugin (2018-07-05, $Rev: 30530 (2018-07-16) $): Quickly post comments to a page without an edit/preview/save cycle
  • DatePickerPlugin (2018-07-05, $Rev: 30446 (2018-07-16) $): Pop-up calendar with date picker, for use in TWiki forms, HTML forms and TWiki plugins
  • EditTablePlugin (2018-07-05, $Rev: 30448 (2018-07-16) $): Edit TWiki tables using edit fields, date pickers and drop down boxes
  • HeadlinesPlugin (2018-07-13, $Rev: 30560 (2018-07-16) $): Show headline news in TWiki pages based on RSS and ATOM news feeds from external sites
  • InterwikiPlugin (2018-07-05, $Rev: 30454 (2018-07-16) $): Write ExternalSite:Page to link to a page on an external site based on aliases defined in a rules topic
  • JQueryPlugin (2018-07-05, $Rev: 30456 (2018-07-16) $): jQuery JavaScript library for TWiki
  • PreferencesPlugin (2018-07-05, $Rev: 30528 (2018-07-16) $): Allows editing of preferences using fields predefined in a form
  • SetGetPlugin (2018-07-05, $Rev: 30472 (2018-07-16) $): Set and get variables and JSON objects in topics, optionally persistently across topic views
  • SlideShowPlugin (2018-07-05, $Rev: 30474 (2018-07-16) $): Create web based presentations based on topics with headings.
  • SmiliesPlugin (2018-07-05, $Rev: 30476 (2018-07-16) $): Render smilies as icons, like  :-) for smile or  :eek: for eek!
  • TWikiSheetPlugin (2018-07-15, $Rev: 30604 (2018-07-16) $): Add TWiki Sheet spreadsheet functionality to TWiki tables
  • TablePlugin (2018-07-05, $Rev: 30480 (2018-07-16) $): Control attributes of tables and sorting of table columns
  • TagMePlugin (2018-07-05, $Rev: 30482 (2018-07-16) $): Tag wiki content collectively or authoritatively to find content by keywords
  • TinyMCEPlugin (2021-06-09, $Rev: 31045 (2021-06-09) $): Integration of the Tiny MCE WYSIWYG Editor
  • TwistyPlugin (2018-07-06, $Rev: 30497 (2018-07-16) $): Twisty section JavaScript library to open/close content dynamically
  • WatchlistPlugin (2018-07-10, $Rev: 30536 (2018-07-16) $): Watch topics of interest and get notified of changes by e-mail
  • WysiwygPlugin (2018-07-06, $Rev: 30528 (2018-07-16) $): Translator framework for WYSIWYG editors

The TWiki Plugin API

The Application Programming Interface (API) for TWikiPlugins provides the specifications for hooking into the core TWiki code from your external Perl Plugin module. The Plugin API is new to the Production version of TWiki with the 01-Sep-2001 release.

Available Core Functions

The TWikiFuncModule (lib/TWiki/Func.pm) implements ALL official Plugin functions. Plugins should ONLY use functions published in this module.

ALERT! If you use functions not in Func.pm, you run the risk of creating security holes. Also, your Plugin will likely break and require updating when you upgrade to a new version of TWiki.

Predefined Hooks

In addition to TWiki core functions, Plugins can use predefined hooks, or call backs, listed in the lib/TWiki/Plugins/EmptyPlugin.pm module.

  • All but the initPlugin are disabled. To enable a call back, remove DISABLE_ from the function name.
  • For best performance, enable only the functions you really need. NOTE: outsidePREHandler and insidePREHandler are particularly expensive.

Most Plugins use either the commonTagsHandler or startRenderingHandler for rendering tasks:

  • commonTagsHandler: Use it to expand %XYZPLUGIN% and %XYZPLUGIN{...}% variables
  • startRenderingHandler: Use it for your own rendering rules or to overload TWiki's internal rendering like [[links]]

TWiki:Codev/StepByStepRenderingOrder helps you decide which rendering handler to use.

Hints on Writing Fast Plugins

  • Delay the Plugin initialization to the actual function which is handling the tag. This way all the expensive initialization is done only when needed.
  • For example, use an eval block like:
    eval { require IPC::Run }
    return "<font color=\"red\">SamplePlugin: Can't load required modules ($@)</font>" if $@;
  • You could return errors as strings to show what happened
  • You can use a flag to avoid running the initialization twice

Plugin Version Detection

To eliminate the incompatibility problems bound to arise from active open Plugin development, a Plugin versioning system and an API GetVersion detection routine are provided for automatic compatibility checking.

  • All modules require a $VERSION='0.000' variable, beginning at 1.000.

  • The initPlugin handler should check all dependencies and return TRUE if the initialization is OK or FALSE if something went wrong.
    • The Plugin initialization code does not register a Plugin that returns FALSE (or that has no initPlugin handler).

Creating Plugins

With a reasonable knowledge of the Perl scripting language, you can create new Plugins or modify and extend existing ones. Basic plug-in architecture uses an Application Programming Interface (API), a set of software instructions that allow external code to interact with the main program. The TWiki Plugin API Plugins by providing a programming interface for TWiki.

The DefaultPlugin Alternative

  • DefaultPlugin can handle some outdated TWiki variables, found, for example, in sites recently updated from an old version. Settings are in DefaultPlugin topic. You can also add your own simple custom processing rules here, though in all but very simple cases, writing a new Plugin is preferable.

Anatomy of a Plugin

A basic TWiki Plugin consists of two elements:

  • a Perl module, ex: MyFirstPlugin.pm
  • a documentation topic, ex: MyFirstPlugin.txt

The Perl module can be a block of code that connects with TWiki alone, or it can include other elements, like other Perl modules (including other Plugins), graphics, TWiki templates, external applications (ex: a Java applet), or just about anything else it can call. In particular, files that should be web-accessible (graphics, Java applets ...) are best placed as attachments of the MyFirstPlugin topic. Other needed Perl code is best placed in a lib/TWiki/Plugins/MyFirstPlugin/ directory.

The Plugin API handles the details of connecting your Perl module with main TWiki code. When you're familiar with the Plugin API, you're ready to develop Plugins.

Creating the Perl Module

Copy file lib/TWiki/Plugins/EmptyPlugin.pm to <name>Plugin.pm. The EmptyPlugin.pm module contains mostly empty functions, so it does nothing, but it's ready to be used. Customize it. Refer to the Plugin API specs for more information.

If your Plugin uses its own modules and objects, you must include the name of the Plugin in the package name. For example, write Package MyFirstPlugin::Attrs; instead of just Package Attrs;. Then call it using:

  use TWiki::Plugins::MyFirstPlugin::Attrs;
  $var = MyFirstPlugin::Attrs->new();

Writing the Documentation Topic

The Plugin documentation topic contains usage instructions and version details. It serves the Plugin files as FileAttachments for downloading. (The doc topic is also included in the distribution package.) To create a documentation topic:

  1. Copy the Plugin topic template from TWiki.org. To copy the text, go to TWiki:Plugins/PluginPackage and:
    • enter the Plugin name in the "How to Create a Plugin" section
    • click Create
    • select all in the Edit box & copy
    • Cancel the edit
    • go back to your site to the TWiki web
    • In the GoBox enter your Plugin name, for example MyFirstPlugin, press enter and create the new topic
    • paste & save new Plugin topic on your site
  2. Customize your Plugin topic.
    • In case you plan to publish your Plugin at TWiki.org, use Interwiki names for author names, like TWiki:Main/TWikiGuest.
  3. Save your topic, for use in packaging and publishing your Plugin.

OUTLINE: Doc Topic Contents
Check the Plugins web on TWiki.org for the latest Plugin doc topic template. Here's a quick overview of what's covered:

Syntax Rules: <Describe any special text formatting that will be rendered.>"

Example: <Include an example of the Plugin in action. Possibly include a static HTML version of the example to compare if the installation was a success!>"

Changed:
<
<
Plugin Global Settings: <Description and settings for custom Plugin %VARIABLES%, and those required by TWiki.>"
>
>
Plugin Settings: <Description and settings for custom Plugin %VARIABLES%, and those required by TWiki.>"
 
  • Plugins Preferences <If user settings are needed, explain... Entering values works exactly like TWikiPreferences and WebPreferences: six (6) spaces and then:>"
    • Set <EXAMPLE = value added>

Plugin Installation Instructions: <Step-by-step set-up guide, user help, whatever it takes to install and run, goes here.>"

Plugin Info: <Version, credits, history, requirements - entered in a form, displayed as a table. Both are automatically generated when you create or edit a page in the TWiki:Plugins web.>"

Packaging for Distribution

A minimum Plugin release consists of a Perl module with a WikiName that ends in Plugin, ex: MyFirstPlugin.pm, and a documentation page with the same name(MyFirstPlugin.txt).

  1. Distribute the Plugin files in a directory structure that mirrors TWiki. If your Plugin uses additional files, include them ALL:
    • lib/TWiki/Plugins/MyFirstPlugin.pm
    • data/TWiki/MyFirstPlugin.txt
    • pub/TWiki/MyFirstPlugin/uparrow.gif [a required graphic]
  2. Create a zip archive with the Plugin name (MyFirstPlugin.zip) and add the entire directory structure from Step 1. The archive should look like this:
    • lib/TWiki/Plugins/MyFirstPlugin.pm
    • data/TWiki/MyFirstPlugin.txt
    • pub/TWiki/MyFirstPlugin/uparrow.gif

Publishing for Public Use

Changed:
<
<
You can release your tested, packaged Plugin to the TWiki community through the TWiki:Plugins web. All Plugins submitted to TWiki.org are available for download and further development in TWiki:Plugins. Publish your Plugin in three steps:
>
>
You can release your tested, packaged Plugin to the TWiki community through the TWiki:Plugins web. All Plugins submitted to TWiki.org are available for download and further development in TWiki:Plugins/PluginPackage. Publish your Plugin in these steps:
 
Changed:
<
<
  1. Post the Plugin documentation topic in the TWiki:Plugins web:
    • create a new topic using the Plugin name, ex: MyFirstPlugin.txt
>
>
  1. Post the Plugin documentation topic in the TWiki:Plugins/PluginPackage:
    • enter the Plugin name in the "How to Create a Plugin" section, for example MyFirstPlugin
 
  1. Attach the distribution zip file to the topic, ex: MyFirstPlugin.zip
  2. Link from the doc page to a new, blank page named after the Plugin, and ending in Dev, ex: MyFirstPluginDev. This is the discussion page for future development. (User support for Plugins is handled in TWiki:Support.)
Added:
>
>
  1. Put the Plugin into the CVS repository, see TWiki:Plugins/ReadmeFirst (optional)
 
Changed:
<
<
-- AndreaSterbini - 29 May 2001
-- PeterThoeny - 11 Dec 2003
-- MikeMannix - 03 Dec 2001
>
>
Thank you very much for sharing your Plugin with the TWiki community smile

Added:
>
>

Recommended Storage of Plugin Data

Plugins sometimes need to store data. This can be Plugin internal data like cache data, or generated data for the browser like images. The following is a recommendation where to store the data.

Where to store Plugin Internal Data

In case the Plugin generates data just for internal use, or data which is not specific to a topic, store it in the Plugin's attachment directory.

  • The Plugin's attachment directory is pubdir/Installweb/FooBarPlugin
    • Installweb refers to the name of the web where the Plugin is installed
  • The Plugin's attachment URL is %PUBURL%/Installweb/FooBarPlugin
  • The filename should start with an underscore, followed by an identifier, e.g. _any_name.ext
    • The leading underscore avoids a nameclash with files attached to the Plugin topic
    • Use only alphanumeric characters, underscores and periods to avoid platform dependency issues and URL issues
    • Do not use subdirectories (rename and delete would fail)
  • Use Plugin API functions documented in TWikiFuncModule to ensure portability:
    • Use getPubDir() to get the attachment root directory
    • Use getUrlHost() and getPubUrlPath() to build the URL in case you create content for the browser
    • Use $installWeb to get the name of the web where the Plugin is installed
    • Create the web directory and topic attachment directory if needed
  • Hint: Package the Plugin at least with one file attachment. This ensures that the attachment directory already exists

Where to Store Data for Topics using the Plugin

In case the Plugin generates data which is specific to a topic, store it in the topic's attachment directory.

  • The topic's attachment directory is pubdir/Webname/TopicName
  • The topic's attachment URL is %PUBURL%/Webname/TopicName
  • The filename should start with an underscore, followed by the Plugin name, an underscore and an identifier, e.g. _FooBarPlugin_any_name.ext
    • The leading underscore avoids a nameclash with files attached to the same topic
    • Use only alphanumeric characters, underscores and periods to avoid platform dependency issues and URL issues
    • Do not use subdirectories (rename and delete would fail)
  • Use Plugin API functions documented in TWikiFuncModule to ensure portability:
    • Use getPubDir() to get the attachment root directory
    • Use getUrlHost() and getPubUrlPath() to build the URL in case you create content for the browser

Example code to build the file name:

sub _make_filename
{
    my ( $web, $topic, $name ) = @_;

    # Create web directory "pub/$web" if needed
    my $dir = TWiki::Func::getPubDir() . "/$web";
    unless( -e "$dir" ) {
        umask( 002 );
        mkdir( $dir, 0775 );
    }
    # Create topic directory "pub/$web/$topic" if needed
    $dir .= "/$topic";
    unless( -e "$dir" ) {
        umask( 002 );
        mkdir( $dir, 0775 );
    }
    return "$dir/_FooBarPlugin_$name";
}

-- TWiki:Main/PeterThoeny - 11 Dec 2003
-- TWiki:Main/AndreaSterbini - 29 May 2001
-- TWiki:Main/MikeMannix - 03 Dec 2001

 

Revision 252003-12-12 - PeterThoeny

 

TWiki Plugins

Plug-in enhanced feature add-ons, with a Plugin API for developers

Overview

You can add Plugins to extend TWiki's functionality, without altering the core program code. A plug-in approach lets you:

  • add virtually unlimited features while keeping the main TWiki code compact and efficient;
  • heavily customize an installation and still do clean updates to new versions of TWiki;
  • rapidly develop new TWiki functions in Perl using the Plugin API.

Everything to do with TWiki Plugins - demos, new releases, downloads, development, general discussion - is available at TWiki.org, in the TWiki:Plugins web.

Preinstalled Plugins

Changed:
<
<
TWiki comes with three Plugins as part of the standard installation.
>
>
TWiki comes with a set of Plugins as part of the standard installation.
 
Changed:
<
<
  • DefaultPlugin optionally handles some legacy variables from older versions of TWiki. You can control this option from TWikiPreferences. (Perl programmers can also add rules for simple custom processing.)
>
>
  • DefaultPlugin: Optionally handles some legacy variables from older versions of TWiki. You can control this option from TWikiPreferences. (Perl programmers can also add rules for simple custom processing.)
Added:
>
>
  • EmptyPlugin: Is a fully functional module, minus active code; it does nothing and serves as a template for new Plugin development.
  • InterwikiPlugin: Use it for shorthand linking to remote sites, ex: TWiki:Plugins expands to TWiki:Plugins on TWiki.org. You can edit the predefined set of of Wiki-related sites, and add your own.
  • EditTablePlugin: Edit TWiki tables using edit fields, date pickers and drop down boxes
  • RenderListPlugin: %RENDERLISTPLUGIN_SHORTDESCRIPTION%
  • SlideShowPlugin: Create web based presentations based on topics with headings.
  • SmiliesPlugin: Render smilies as icons, like  :-) for smile or  :eek: for eek!
  • SpreadSheetPlugin: Add spreadsheet calculation like "$SUM( $ABOVE() )" to TWiki tables or anywhere in topic text
  • TablePlugin: Control attributes of tables and sorting of table columns
 
Deleted:
<
<
  • EmptyPlugin is a fully functional module, minus active code; it does nothing and serves as a template for new Plugin development.

  • InterwikiPlugin is preinstalled but can be disabled or removed. Use it for shorthand linking to remote sites, ex: TWiki:Plugins expands to TWiki:Plugins on TWiki.org. You can edit the predefined set of of Wiki-related sites, and add your own.
 

Installing Plugins

Each TWikiPlugin comes with full documentation: step-by-step installation instructions, a detailed description of any special requirements, version details, and a working example for testing.

Most Plugins can be installed in three easy steps, with no programming skills required:

  1. Download the zip file containing the Plugin, documentation, and any other required files, from TWiki:Plugins.
  2. Distribute the files to their proper locations - unzip the zip archive in your TWiki installation directory - if have a standard TWiki installation, this will distribute automatically. Otherwise, place the files according to the directory paths listed on the Plugin top in TWiki:Plugins.
  3. Check the demo example on the Plugin topic: if it's working, the installation was fine!

Special Requests: Some Plugins need certain Perl modules to be preinstalled on the host system. Plugins may also use other resources, like graphics, other modules, applications, templates. In these cases, detailed instructions are in the Plugin documentation.

Each Plugin has a standard release page, located in the TWiki:Plugins web at TWiki.org. In addition to the documentation topic (SomePlugin), there's a separate development page.

  • Doc page: Read all available info about the Plugin; download the attached distribution files.
  • Dev page: Post feature requests, bug reports and general dev comments; topic title ends in Dev (SomePluginDev).
  • User support: Post installation, how to use type questions (and answers, if you have them) in the TWiki:Support web.

On-Site Pretesting

To test new Plugins on your installation before making them public, you may want to use one of these two approaches:

  • Method 1: Safely test on-the-fly by creating separate Production and Test branches in your live TWiki installation.
    • Duplicate the twiki/bin and twiki/lib directories for the Test version, and adjust the paths in the new lib/TWiki.cfg. The following directories are shared: twiki/data, twiki/templates and twiki/pub.
    • Test Plugins and other new features in the Test installation until you're satisfied.
      • ALERT! If you modify topics using the new features, live users will likely see unfamiliar new META tags showing up on their pages - to avoid this, create and edit test-only topics to try out new features.
    • Copy the modified files to the Production installation. You can update a TWiki installation live and users won't even notice.

  • Method 2: List the Plugin being tested in the DISABLEDPLUGINS variable in TWikiPreferences. Redefine the DISABLEDPLUGINS variable in the Sandbox web and do the testing there.
Changed:
<
<

A Note on Performance

>
>

A Note on Plugin Performance

 
Changed:
<
<
The performance of the system depends on the number of Plugins installed and on the Plugin implementation. Some Plugins impose no measurable performance decrease, some do. For example, outsidePREHandler is an expensive callback function, or a Plugin might use many Perl libraries that needs to be initialized with each page view (unless you run mod_perl). It is recommended to measure the performance with and without a new Plugin. Example for Unix:
time wget -qO /dev/null https://wiki.ivoa.net/twiki/bin/view/TWiki/AbcPlugin
>
>
The performance of the system depends on the number of Plugins installed and on the Plugin implementation. Some Plugins impose no measurable performance decrease, some do. For example, outsidePREHandler is an expensive callback function, or a Plugin might use many Perl libraries that need to be initialized with each page view (unless you run mod_perl). It is recommended to measure the performance with and without a new Plugin. Example for Unix:
time wget -qO /dev/null https://wiki.ivoa.net/twiki/bin/view/TWiki/AbcPlugin
  In case you need to install an "expensive" Plugin and you need its functionality only in one web you can place the Plugin topic into that web. TWiki will initialize the Plugin only if the Plugin topic is found (which won't be the case for other webs.)

Managing Plugins

When you finish installing a Plugin, you should be able to read the user instructions and go. In fact, some Plugins require additional settings or offer extra options that you have to select. Also, you may want to make a Plugin available only in certain webs, or temporarily disable it. And may want to list all available Plugins in certain topics. You can handle all of these management tasks with simple procedures.

Setting Preferences

Installed Plugins can be toggled on or off, site-wide or by web, through TWikiPreferences and individual WebPreferences:

  • All Plugin modules present in the lib/TWiki/Plugins directory are activated automatically unless disabled by the DISABLEDPLUGINS Preferences variable in TWikiPreferences. You can optionally list the installed Plugins in the INSTALLEDPLUGINS Preferences variable. This is useful to define the sequence of Plugin execution, or to specify other webs than the TWiki web for the Plugin topics. Settings in TWikiPreferences are:
    • Set INSTALLEDPLUGINS = DefaultPlugin, ...
    • Set DISABLEDPLUGINS = EmptyPlugin, ...

Plugin execution order in TWiki is determined by searching Plugin topics in a specific sequence: First, full web.topicname name, if specified in INSTALLEDPLUGINS; next, the TWiki web is searched; and finally, the current web.

Plugin-specific settings are done in individual Plugin topics. Two settings are standard for each Plugin:

  1. One line description, used to form the bullets describing the Plugins in the TextFormattingRules topic:
    • Set SHORTDESCRIPTION = Blah blah woof woof.
  2. Debug Plugin, output can be seen in data/debug.txt. Set to 0=off or 1=on:
    • Set DEBUG = 0
  • The settings can be retrieved as Preferences variables like %<pluginname>_<var>%, ex: %DEFAULTPLUGIN_SHORTDESCRIPTION% shows the description of the DefaultPlugin.

Listing Active Plugins

Plugin status variables let you list all active Plugins wherever needed. There are two list formats:

  • The %ACTIVATEDPLUGINS% variable lists activated Plugins by name. (This variable is displayed in TWikiPreferences for debugging use.)
  • The %PLUGINDESCRIPTIONS% variable displays a bullet list with a one-line description of each active Plugins. This variable is based on the %<plugin>_SHORTDESCRIPTION% Preferences variables of individual topics and is shown in TextFormattingRules.

DEMO: Automatically List Active Plugins Using Variables

Using %ACTIVATEDPLUGINS%:
On this TWiki site, the active Plugins are: SpreadSheetPlugin, BackupRestorePlugin, ColorPickerPlugin, CommentPlugin, DatePickerPlugin, EditTablePlugin, HeadlinesPlugin, InterwikiPlugin, JQueryPlugin, PreferencesPlugin, SetGetPlugin, SlideShowPlugin, SmiliesPlugin, TWikiSheetPlugin, TablePlugin, TagMePlugin, TinyMCEPlugin, TwistyPlugin, WatchlistPlugin, WysiwygPlugin.

Using %PLUGINDESCRIPTIONS%:
You can use any of these active TWiki Plugins:

  • SpreadSheetPlugin (2018-07-05, $Rev: 30478 (2018-07-16) $): Add spreadsheet calculation like "$SUM( $ABOVE() )" to TWiki tables or anywhere in topic text
  • BackupRestorePlugin (2021-03-19, $Rev: 30914 (2021-03-19) $): Administrator utility to backup, restore and upgrade a TWiki site
  • ColorPickerPlugin (2018-07-05, $Rev: 30442 (2018-07-16) $): Color picker, packaged for use in TWiki forms and TWiki applications
  • CommentPlugin (2018-07-05, $Rev: 30530 (2018-07-16) $): Quickly post comments to a page without an edit/preview/save cycle
  • DatePickerPlugin (2018-07-05, $Rev: 30446 (2018-07-16) $): Pop-up calendar with date picker, for use in TWiki forms, HTML forms and TWiki plugins
  • EditTablePlugin (2018-07-05, $Rev: 30448 (2018-07-16) $): Edit TWiki tables using edit fields, date pickers and drop down boxes
  • HeadlinesPlugin (2018-07-13, $Rev: 30560 (2018-07-16) $): Show headline news in TWiki pages based on RSS and ATOM news feeds from external sites
  • InterwikiPlugin (2018-07-05, $Rev: 30454 (2018-07-16) $): Write ExternalSite:Page to link to a page on an external site based on aliases defined in a rules topic
  • JQueryPlugin (2018-07-05, $Rev: 30456 (2018-07-16) $): jQuery JavaScript library for TWiki
  • PreferencesPlugin (2018-07-05, $Rev: 30528 (2018-07-16) $): Allows editing of preferences using fields predefined in a form
  • SetGetPlugin (2018-07-05, $Rev: 30472 (2018-07-16) $): Set and get variables and JSON objects in topics, optionally persistently across topic views
  • SlideShowPlugin (2018-07-05, $Rev: 30474 (2018-07-16) $): Create web based presentations based on topics with headings.
  • SmiliesPlugin (2018-07-05, $Rev: 30476 (2018-07-16) $): Render smilies as icons, like  :-) for smile or  :eek: for eek!
  • TWikiSheetPlugin (2018-07-15, $Rev: 30604 (2018-07-16) $): Add TWiki Sheet spreadsheet functionality to TWiki tables
  • TablePlugin (2018-07-05, $Rev: 30480 (2018-07-16) $): Control attributes of tables and sorting of table columns
  • TagMePlugin (2018-07-05, $Rev: 30482 (2018-07-16) $): Tag wiki content collectively or authoritatively to find content by keywords
  • TinyMCEPlugin (2021-06-09, $Rev: 31045 (2021-06-09) $): Integration of the Tiny MCE WYSIWYG Editor
  • TwistyPlugin (2018-07-06, $Rev: 30497 (2018-07-16) $): Twisty section JavaScript library to open/close content dynamically
  • WatchlistPlugin (2018-07-10, $Rev: 30536 (2018-07-16) $): Watch topics of interest and get notified of changes by e-mail
  • WysiwygPlugin (2018-07-06, $Rev: 30528 (2018-07-16) $): Translator framework for WYSIWYG editors

The TWiki Plugin API

The Application Programming Interface (API) for TWikiPlugins provides the specifications for hooking into the core TWiki code from your external Perl Plugin module. The Plugin API is new to the Production version of TWiki with the 01-Sep-2001 release.

Available Core Functions

The TWikiFuncModule (lib/TWiki/Func.pm) implements ALL official Plugin functions. Plugins should ONLY use functions published in this module.

ALERT! If you use functions not in Func.pm, you run the risk of creating security holes. Also, your Plugin will likely break and require updating when you upgrade to a new version of TWiki.

Predefined Hooks

In addition to TWiki core functions, Plugins can use predefined hooks, or call backs, listed in the lib/TWiki/Plugins/EmptyPlugin.pm module.

  • All but the initPlugin are disabled. To enable a call back, remove DISABLE_ from the function name.
  • For best performance, enable only the functions you really need. NOTE: outsidePREHandler and insidePREHandler are particularly expensive.
Added:
>
>
Most Plugins use either the commonTagsHandler or startRenderingHandler for rendering tasks:
  • commonTagsHandler: Use it to expand %XYZPLUGIN% and %XYZPLUGIN{...}% variables
  • startRenderingHandler: Use it for your own rendering rules or to overload TWiki's internal rendering like [[links]]

TWiki:Codev/StepByStepRenderingOrder helps you decide which rendering handler to use.

Hints on Writing Fast Plugins

  • Delay the Plugin initialization to the actual function which is handling the tag. This way all the expensive initialization is done only when needed.
  • For example, use an eval block like:
    eval { require IPC::Run }
    return "<font color=\"red\">SamplePlugin: Can't load required modules ($@)</font>" if $@;
  • You could return errors as strings to show what happened
  • You can use a flag to avoid running the initialization twice
 

Plugin Version Detection

To eliminate the incompatibility problems bound to arise from active open Plugin development, a Plugin versioning system and an API GetVersion detection routine are provided for automatic compatibility checking.

  • All modules require a $VERSION='0.000' variable, beginning at 1.000.

  • The initPlugin handler should check all dependencies and return TRUE if the initialization is OK or FALSE if something went wrong.
    • The Plugin initialization code does not register a Plugin that returns FALSE (or that has no initPlugin handler).

Creating Plugins

With a reasonable knowledge of the Perl scripting language, you can create new Plugins or modify and extend existing ones. Basic plug-in architecture uses an Application Programming Interface (API), a set of software instructions that allow external code to interact with the main program. The TWiki Plugin API Plugins by providing a programming interface for TWiki.

The DefaultPlugin Alternative

  • DefaultPlugin can handle some outdated TWiki variables, found, for example, in sites recently updated from an old version. Settings are in DefaultPlugin topic. You can also add your own simple custom processing rules here, though in all but very simple cases, writing a new Plugin is preferable.

Anatomy of a Plugin

A basic TWiki Plugin consists of two elements:

  • a Perl module, ex: MyFirstPlugin.pm
  • a documentation topic, ex: MyFirstPlugin.txt

The Perl module can be a block of code that connects with TWiki alone, or it can include other elements, like other Perl modules (including other Plugins), graphics, TWiki templates, external applications (ex: a Java applet), or just about anything else it can call. In particular, files that should be web-accessible (graphics, Java applets ...) are best placed as attachments of the MyFirstPlugin topic. Other needed Perl code is best placed in a lib/TWiki/Plugins/MyFirstPlugin/ directory.

The Plugin API handles the details of connecting your Perl module with main TWiki code. When you're familiar with the Plugin API, you're ready to develop Plugins.

Creating the Perl Module

Copy file lib/TWiki/Plugins/EmptyPlugin.pm to <name>Plugin.pm. The EmptyPlugin.pm module contains mostly empty functions, so it does nothing, but it's ready to be used. Customize it. Refer to the Plugin API specs for more information.

If your Plugin uses its own modules and objects, you must include the name of the Plugin in the package name. For example, write Package MyFirstPlugin::Attrs; instead of just Package Attrs;. Then call it using:

  use TWiki::Plugins::MyFirstPlugin::Attrs;
  $var = MyFirstPlugin::Attrs->new();

Writing the Documentation Topic

The Plugin documentation topic contains usage instructions and version details. It serves the Plugin files as FileAttachments for downloading. (The doc topic is also included in the distribution package.) To create a documentation topic:

  1. Copy the Plugin topic template from TWiki.org. To copy the text, go to TWiki:Plugins/PluginPackage and:
    • enter the Plugin name in the "How to Create a Plugin" section
    • click Create
    • select all in the Edit box & copy
    • Cancel the edit
    • go back to your site to the TWiki web
    • In the GoBox enter your Plugin name, for example MyFirstPlugin, press enter and create the new topic
    • paste & save new Plugin topic on your site
  2. Customize your Plugin topic.
    • In case you plan to publish your Plugin at TWiki.org, use Interwiki names for author names, like TWiki:Main/TWikiGuest.
  3. Save your topic, for use in packaging and publishing your Plugin.

OUTLINE: Doc Topic Contents
Check the Plugins web on TWiki.org for the latest Plugin doc topic template. Here's a quick overview of what's covered:

Syntax Rules: <Describe any special text formatting that will be rendered.>"

Example: <Include an example of the Plugin in action. Possibly include a static HTML version of the example to compare if the installation was a success!>"

Plugin Global Settings: <Description and settings for custom Plugin %VARIABLES%, and those required by TWiki.>"

  • Plugins Preferences <If user settings are needed, explain... Entering values works exactly like TWikiPreferences and WebPreferences: six (6) spaces and then:>"
    • Set <EXAMPLE = value added>

Plugin Installation Instructions: <Step-by-step set-up guide, user help, whatever it takes to install and run, goes here.>"

Plugin Info: <Version, credits, history, requirements - entered in a form, displayed as a table. Both are automatically generated when you create or edit a page in the TWiki:Plugins web.>"

Packaging for Distribution

A minimum Plugin release consists of a Perl module with a WikiName that ends in Plugin, ex: MyFirstPlugin.pm, and a documentation page with the same name(MyFirstPlugin.txt).

  1. Distribute the Plugin files in a directory structure that mirrors TWiki. If your Plugin uses additional files, include them ALL:
    • lib/TWiki/Plugins/MyFirstPlugin.pm
    • data/TWiki/MyFirstPlugin.txt
    • pub/TWiki/MyFirstPlugin/uparrow.gif [a required graphic]
  2. Create a zip archive with the Plugin name (MyFirstPlugin.zip) and add the entire directory structure from Step 1. The archive should look like this:
    • lib/TWiki/Plugins/MyFirstPlugin.pm
    • data/TWiki/MyFirstPlugin.txt
    • pub/TWiki/MyFirstPlugin/uparrow.gif

Publishing for Public Use

You can release your tested, packaged Plugin to the TWiki community through the TWiki:Plugins web. All Plugins submitted to TWiki.org are available for download and further development in TWiki:Plugins. Publish your Plugin in three steps:

  1. Post the Plugin documentation topic in the TWiki:Plugins web:
  2. Attach the distribution zip file to the topic, ex: MyFirstPlugin.zip
  3. Link from the doc page to a new, blank page named after the Plugin, and ending in Dev, ex: MyFirstPluginDev. This is the discussion page for future development. (User support for Plugins is handled in TWiki:Support.)

-- AndreaSterbini - 29 May 2001

Changed:
<
<
-- PeterThoeny - 29 Jan 2003
>
>
-- PeterThoeny - 11 Dec 2003
 -- MikeMannix - 03 Dec 2001

Revision 242003-08-01 - PeterThoeny

 

TWiki Plugins

Plug-in enhanced feature add-ons, with a Plugin API for developers

Overview

You can add Plugins to extend TWiki's functionality, without altering the core program code. A plug-in approach lets you:

  • add virtually unlimited features while keeping the main TWiki code compact and efficient;
  • heavily customize an installation and still do clean updates to new versions of TWiki;
  • rapidly develop new TWiki functions in Perl using the Plugin API.

Everything to do with TWiki Plugins - demos, new releases, downloads, development, general discussion - is available at TWiki.org, in the TWiki:Plugins web.

Preinstalled Plugins

TWiki comes with three Plugins as part of the standard installation.

  • DefaultPlugin optionally handles some legacy variables from older versions of TWiki. You can control this option from TWikiPreferences. (Perl programmers can also add rules for simple custom processing.)

  • EmptyPlugin is a fully functional module, minus active code; it does nothing and serves as a template for new Plugin development.

  • InterwikiPlugin is preinstalled but can be disabled or removed. Use it for shorthand linking to remote sites, ex: TWiki:Plugins expands to TWiki:Plugins on TWiki.org. You can edit the predefined set of of Wiki-related sites, and add your own.

Installing Plugins

Each TWikiPlugin comes with full documentation: step-by-step installation instructions, a detailed description of any special requirements, version details, and a working example for testing.

Most Plugins can be installed in three easy steps, with no programming skills required:

  1. Download the zip file containing the Plugin, documentation, and any other required files, from TWiki:Plugins.
  2. Distribute the files to their proper locations - unzip the zip archive in your TWiki installation directory - if have a standard TWiki installation, this will distribute automatically. Otherwise, place the files according to the directory paths listed on the Plugin top in TWiki:Plugins.
  3. Check the demo example on the Plugin topic: if it's working, the installation was fine!

Special Requests: Some Plugins need certain Perl modules to be preinstalled on the host system. Plugins may also use other resources, like graphics, other modules, applications, templates. In these cases, detailed instructions are in the Plugin documentation.

Each Plugin has a standard release page, located in the TWiki:Plugins web at TWiki.org. In addition to the documentation topic (SomePlugin), there's a separate development page.

  • Doc page: Read all available info about the Plugin; download the attached distribution files.
  • Dev page: Post feature requests, bug reports and general dev comments; topic title ends in Dev (SomePluginDev).
  • User support: Post installation, how to use type questions (and answers, if you have them) in the TWiki:Support web.

On-Site Pretesting

To test new Plugins on your installation before making them public, you may want to use one of these two approaches:

  • Method 1: Safely test on-the-fly by creating separate Production and Test branches in your live TWiki installation.
    • Duplicate the twiki/bin and twiki/lib directories for the Test version, and adjust the paths in the new lib/TWiki.cfg. The following directories are shared: twiki/data, twiki/templates and twiki/pub.
    • Test Plugins and other new features in the Test installation until you're satisfied.
      • ALERT! If you modify topics using the new features, live users will likely see unfamiliar new META tags showing up on their pages - to avoid this, create and edit test-only topics to try out new features.
    • Copy the modified files to the Production installation. You can update a TWiki installation live and users won't even notice.

  • Method 2: List the Plugin being tested in the DISABLEDPLUGINS variable in TWikiPreferences. Redefine the DISABLEDPLUGINS variable in the Sandbox web and do the testing there.

A Note on Performance

Changed:
<
<
The performance of the system depends on the number of Plugins installed and on the Plugin implementation. Some Plugins impose no measurable performance decrease, some do. For example, outsidePREHandler is an expensive callback function, or a Plugin might use many Perl libraries that needs to be initialized with each page view (unless you run mod_perl). It is recommended to measure the performance with and without a new Plugin.
>
>
The performance of the system depends on the number of Plugins installed and on the Plugin implementation. Some Plugins impose no measurable performance decrease, some do. For example, outsidePREHandler is an expensive callback function, or a Plugin might use many Perl libraries that needs to be initialized with each page view (unless you run mod_perl). It is recommended to measure the performance with and without a new Plugin. Example for Unix:
time wget -qO /dev/null https://wiki.ivoa.net/twiki/bin/view/TWiki/AbcPlugin
  In case you need to install an "expensive" Plugin and you need its functionality only in one web you can place the Plugin topic into that web. TWiki will initialize the Plugin only if the Plugin topic is found (which won't be the case for other webs.)

Managing Plugins

When you finish installing a Plugin, you should be able to read the user instructions and go. In fact, some Plugins require additional settings or offer extra options that you have to select. Also, you may want to make a Plugin available only in certain webs, or temporarily disable it. And may want to list all available Plugins in certain topics. You can handle all of these management tasks with simple procedures.

Setting Preferences

Installed Plugins can be toggled on or off, site-wide or by web, through TWikiPreferences and individual WebPreferences:

  • All Plugin modules present in the lib/TWiki/Plugins directory are activated automatically unless disabled by the DISABLEDPLUGINS Preferences variable in TWikiPreferences. You can optionally list the installed Plugins in the INSTALLEDPLUGINS Preferences variable. This is useful to define the sequence of Plugin execution, or to specify other webs than the TWiki web for the Plugin topics. Settings in TWikiPreferences are:
    • Set INSTALLEDPLUGINS = DefaultPlugin, ...
    • Set DISABLEDPLUGINS = EmptyPlugin, ...

Plugin execution order in TWiki is determined by searching Plugin topics in a specific sequence: First, full web.topicname name, if specified in INSTALLEDPLUGINS; next, the TWiki web is searched; and finally, the current web.

Plugin-specific settings are done in individual Plugin topics. Two settings are standard for each Plugin:

  1. One line description, used to form the bullets describing the Plugins in the TextFormattingRules topic:
    • Set SHORTDESCRIPTION = Blah blah woof woof.
  2. Debug Plugin, output can be seen in data/debug.txt. Set to 0=off or 1=on:
    • Set DEBUG = 0
  • The settings can be retrieved as Preferences variables like %<pluginname>_<var>%, ex: %DEFAULTPLUGIN_SHORTDESCRIPTION% shows the description of the DefaultPlugin.

Listing Active Plugins

Plugin status variables let you list all active Plugins wherever needed. There are two list formats:

  • The %ACTIVATEDPLUGINS% variable lists activated Plugins by name. (This variable is displayed in TWikiPreferences for debugging use.)
  • The %PLUGINDESCRIPTIONS% variable displays a bullet list with a one-line description of each active Plugins. This variable is based on the %<plugin>_SHORTDESCRIPTION% Preferences variables of individual topics and is shown in TextFormattingRules.

DEMO: Automatically List Active Plugins Using Variables

Using %ACTIVATEDPLUGINS%:
On this TWiki site, the active Plugins are: SpreadSheetPlugin, BackupRestorePlugin, ColorPickerPlugin, CommentPlugin, DatePickerPlugin, EditTablePlugin, HeadlinesPlugin, InterwikiPlugin, JQueryPlugin, PreferencesPlugin, SetGetPlugin, SlideShowPlugin, SmiliesPlugin, TWikiSheetPlugin, TablePlugin, TagMePlugin, TinyMCEPlugin, TwistyPlugin, WatchlistPlugin, WysiwygPlugin.

Using %PLUGINDESCRIPTIONS%:
You can use any of these active TWiki Plugins:

  • SpreadSheetPlugin (2018-07-05, $Rev: 30478 (2018-07-16) $): Add spreadsheet calculation like "$SUM( $ABOVE() )" to TWiki tables or anywhere in topic text
  • BackupRestorePlugin (2021-03-19, $Rev: 30914 (2021-03-19) $): Administrator utility to backup, restore and upgrade a TWiki site
  • ColorPickerPlugin (2018-07-05, $Rev: 30442 (2018-07-16) $): Color picker, packaged for use in TWiki forms and TWiki applications
  • CommentPlugin (2018-07-05, $Rev: 30530 (2018-07-16) $): Quickly post comments to a page without an edit/preview/save cycle
  • DatePickerPlugin (2018-07-05, $Rev: 30446 (2018-07-16) $): Pop-up calendar with date picker, for use in TWiki forms, HTML forms and TWiki plugins
  • EditTablePlugin (2018-07-05, $Rev: 30448 (2018-07-16) $): Edit TWiki tables using edit fields, date pickers and drop down boxes
  • HeadlinesPlugin (2018-07-13, $Rev: 30560 (2018-07-16) $): Show headline news in TWiki pages based on RSS and ATOM news feeds from external sites
  • InterwikiPlugin (2018-07-05, $Rev: 30454 (2018-07-16) $): Write ExternalSite:Page to link to a page on an external site based on aliases defined in a rules topic
  • JQueryPlugin (2018-07-05, $Rev: 30456 (2018-07-16) $): jQuery JavaScript library for TWiki
  • PreferencesPlugin (2018-07-05, $Rev: 30528 (2018-07-16) $): Allows editing of preferences using fields predefined in a form
  • SetGetPlugin (2018-07-05, $Rev: 30472 (2018-07-16) $): Set and get variables and JSON objects in topics, optionally persistently across topic views
  • SlideShowPlugin (2018-07-05, $Rev: 30474 (2018-07-16) $): Create web based presentations based on topics with headings.
  • SmiliesPlugin (2018-07-05, $Rev: 30476 (2018-07-16) $): Render smilies as icons, like  :-) for smile or  :eek: for eek!
  • TWikiSheetPlugin (2018-07-15, $Rev: 30604 (2018-07-16) $): Add TWiki Sheet spreadsheet functionality to TWiki tables
  • TablePlugin (2018-07-05, $Rev: 30480 (2018-07-16) $): Control attributes of tables and sorting of table columns
  • TagMePlugin (2018-07-05, $Rev: 30482 (2018-07-16) $): Tag wiki content collectively or authoritatively to find content by keywords
  • TinyMCEPlugin (2021-06-09, $Rev: 31045 (2021-06-09) $): Integration of the Tiny MCE WYSIWYG Editor
  • TwistyPlugin (2018-07-06, $Rev: 30497 (2018-07-16) $): Twisty section JavaScript library to open/close content dynamically
  • WatchlistPlugin (2018-07-10, $Rev: 30536 (2018-07-16) $): Watch topics of interest and get notified of changes by e-mail
  • WysiwygPlugin (2018-07-06, $Rev: 30528 (2018-07-16) $): Translator framework for WYSIWYG editors

The TWiki Plugin API

The Application Programming Interface (API) for TWikiPlugins provides the specifications for hooking into the core TWiki code from your external Perl Plugin module. The Plugin API is new to the Production version of TWiki with the 01-Sep-2001 release.

Available Core Functions

The TWikiFuncModule (lib/TWiki/Func.pm) implements ALL official Plugin functions. Plugins should ONLY use functions published in this module.

ALERT! If you use functions not in Func.pm, you run the risk of creating security holes. Also, your Plugin will likely break and require updating when you upgrade to a new version of TWiki.

Predefined Hooks

In addition to TWiki core functions, Plugins can use predefined hooks, or call backs, listed in the lib/TWiki/Plugins/EmptyPlugin.pm module.

  • All but the initPlugin are disabled. To enable a call back, remove DISABLE_ from the function name.
  • For best performance, enable only the functions you really need. NOTE: outsidePREHandler and insidePREHandler are particularly expensive.

Plugin Version Detection

To eliminate the incompatibility problems bound to arise from active open Plugin development, a Plugin versioning system and an API GetVersion detection routine are provided for automatic compatibility checking.

  • All modules require a $VERSION='0.000' variable, beginning at 1.000.

  • The initPlugin handler should check all dependencies and return TRUE if the initialization is OK or FALSE if something went wrong.
    • The Plugin initialization code does not register a Plugin that returns FALSE (or that has no initPlugin handler).

Creating Plugins

With a reasonable knowledge of the Perl scripting language, you can create new Plugins or modify and extend existing ones. Basic plug-in architecture uses an Application Programming Interface (API), a set of software instructions that allow external code to interact with the main program. The TWiki Plugin API Plugins by providing a programming interface for TWiki.

The DefaultPlugin Alternative

  • DefaultPlugin can handle some outdated TWiki variables, found, for example, in sites recently updated from an old version. Settings are in DefaultPlugin topic. You can also add your own simple custom processing rules here, though in all but very simple cases, writing a new Plugin is preferable.

Anatomy of a Plugin

A basic TWiki Plugin consists of two elements:

  • a Perl module, ex: MyFirstPlugin.pm
  • a documentation topic, ex: MyFirstPlugin.txt

The Perl module can be a block of code that connects with TWiki alone, or it can include other elements, like other Perl modules (including other Plugins), graphics, TWiki templates, external applications (ex: a Java applet), or just about anything else it can call. In particular, files that should be web-accessible (graphics, Java applets ...) are best placed as attachments of the MyFirstPlugin topic. Other needed Perl code is best placed in a lib/TWiki/Plugins/MyFirstPlugin/ directory.

The Plugin API handles the details of connecting your Perl module with main TWiki code. When you're familiar with the Plugin API, you're ready to develop Plugins.

Creating the Perl Module

Copy file lib/TWiki/Plugins/EmptyPlugin.pm to <name>Plugin.pm. The EmptyPlugin.pm module contains mostly empty functions, so it does nothing, but it's ready to be used. Customize it. Refer to the Plugin API specs for more information.

If your Plugin uses its own modules and objects, you must include the name of the Plugin in the package name. For example, write Package MyFirstPlugin::Attrs; instead of just Package Attrs;. Then call it using:

  use TWiki::Plugins::MyFirstPlugin::Attrs;
  $var = MyFirstPlugin::Attrs->new();

Writing the Documentation Topic

The Plugin documentation topic contains usage instructions and version details. It serves the Plugin files as FileAttachments for downloading. (The doc topic is also included in the distribution package.) To create a documentation topic:

  1. Copy the Plugin topic template from TWiki.org. To copy the text, go to TWiki:Plugins/PluginPackage and:
    • enter the Plugin name in the "How to Create a Plugin" section
    • click Create
    • select all in the Edit box & copy
    • Cancel the edit
    • go back to your site to the TWiki web
    • In the GoBox enter your Plugin name, for example MyFirstPlugin, press enter and create the new topic
    • paste & save new Plugin topic on your site
  2. Customize your Plugin topic.
    • In case you plan to publish your Plugin at TWiki.org, use Interwiki names for author names, like TWiki:Main/TWikiGuest.
  3. Save your topic, for use in packaging and publishing your Plugin.

OUTLINE: Doc Topic Contents
Check the Plugins web on TWiki.org for the latest Plugin doc topic template. Here's a quick overview of what's covered:

Syntax Rules: <Describe any special text formatting that will be rendered.>"

Example: <Include an example of the Plugin in action. Possibly include a static HTML version of the example to compare if the installation was a success!>"

Plugin Global Settings: <Description and settings for custom Plugin %VARIABLES%, and those required by TWiki.>"

  • Plugins Preferences <If user settings are needed, explain... Entering values works exactly like TWikiPreferences and WebPreferences: six (6) spaces and then:>"
    • Set <EXAMPLE = value added>

Plugin Installation Instructions: <Step-by-step set-up guide, user help, whatever it takes to install and run, goes here.>"

Plugin Info: <Version, credits, history, requirements - entered in a form, displayed as a table. Both are automatically generated when you create or edit a page in the TWiki:Plugins web.>"

Packaging for Distribution

A minimum Plugin release consists of a Perl module with a WikiName that ends in Plugin, ex: MyFirstPlugin.pm, and a documentation page with the same name(MyFirstPlugin.txt).

  1. Distribute the Plugin files in a directory structure that mirrors TWiki. If your Plugin uses additional files, include them ALL:
    • lib/TWiki/Plugins/MyFirstPlugin.pm
    • data/TWiki/MyFirstPlugin.txt
    • pub/TWiki/MyFirstPlugin/uparrow.gif [a required graphic]
  2. Create a zip archive with the Plugin name (MyFirstPlugin.zip) and add the entire directory structure from Step 1. The archive should look like this:
    • lib/TWiki/Plugins/MyFirstPlugin.pm
    • data/TWiki/MyFirstPlugin.txt
    • pub/TWiki/MyFirstPlugin/uparrow.gif

Publishing for Public Use

You can release your tested, packaged Plugin to the TWiki community through the TWiki:Plugins web. All Plugins submitted to TWiki.org are available for download and further development in TWiki:Plugins. Publish your Plugin in three steps:

  1. Post the Plugin documentation topic in the TWiki:Plugins web:
  2. Attach the distribution zip file to the topic, ex: MyFirstPlugin.zip
  3. Link from the doc page to a new, blank page named after the Plugin, and ending in Dev, ex: MyFirstPluginDev. This is the discussion page for future development. (User support for Plugins is handled in TWiki:Support.)

-- AndreaSterbini - 29 May 2001
-- PeterThoeny - 29 Jan 2003
-- MikeMannix - 03 Dec 2001

Revision 232003-08-01 - PeterThoeny

 

TWiki Plugins

Plug-in enhanced feature add-ons, with a Plugin API for developers

Overview

You can add Plugins to extend TWiki's functionality, without altering the core program code. A plug-in approach lets you:

  • add virtually unlimited features while keeping the main TWiki code compact and efficient;
  • heavily customize an installation and still do clean updates to new versions of TWiki;
  • rapidly develop new TWiki functions in Perl using the Plugin API.

Everything to do with TWiki Plugins - demos, new releases, downloads, development, general discussion - is available at TWiki.org, in the TWiki:Plugins web.

Preinstalled Plugins

TWiki comes with three Plugins as part of the standard installation.

  • DefaultPlugin optionally handles some legacy variables from older versions of TWiki. You can control this option from TWikiPreferences. (Perl programmers can also add rules for simple custom processing.)

  • EmptyPlugin is a fully functional module, minus active code; it does nothing and serves as a template for new Plugin development.

  • InterwikiPlugin is preinstalled but can be disabled or removed. Use it for shorthand linking to remote sites, ex: TWiki:Plugins expands to TWiki:Plugins on TWiki.org. You can edit the predefined set of of Wiki-related sites, and add your own.

Installing Plugins

Each TWikiPlugin comes with full documentation: step-by-step installation instructions, a detailed description of any special requirements, version details, and a working example for testing.

Most Plugins can be installed in three easy steps, with no programming skills required:

  1. Download the zip file containing the Plugin, documentation, and any other required files, from TWiki:Plugins.
  2. Distribute the files to their proper locations - unzip the zip archive in your TWiki installation directory - if have a standard TWiki installation, this will distribute automatically. Otherwise, place the files according to the directory paths listed on the Plugin top in TWiki:Plugins.
  3. Check the demo example on the Plugin topic: if it's working, the installation was fine!

Special Requests: Some Plugins need certain Perl modules to be preinstalled on the host system. Plugins may also use other resources, like graphics, other modules, applications, templates. In these cases, detailed instructions are in the Plugin documentation.

Each Plugin has a standard release page, located in the TWiki:Plugins web at TWiki.org. In addition to the documentation topic (SomePlugin), there's a separate development page.

  • Doc page: Read all available info about the Plugin; download the attached distribution files.
  • Dev page: Post feature requests, bug reports and general dev comments; topic title ends in Dev (SomePluginDev).
  • User support: Post installation, how to use type questions (and answers, if you have them) in the TWiki:Support web.

On-Site Pretesting

To test new Plugins on your installation before making them public, you may want to use one of these two approaches:

  • Method 1: Safely test on-the-fly by creating separate Production and Test branches in your live TWiki installation.
    • Duplicate the twiki/bin and twiki/lib directories for the Test version, and adjust the paths in the new lib/TWiki.cfg. The following directories are shared: twiki/data, twiki/templates and twiki/pub.
    • Test Plugins and other new features in the Test installation until you're satisfied.
      • ALERT! If you modify topics using the new features, live users will likely see unfamiliar new META tags showing up on their pages - to avoid this, create and edit test-only topics to try out new features.
    • Copy the modified files to the Production installation. You can update a TWiki installation live and users won't even notice.

  • Method 2: List the Plugin being tested in the DISABLEDPLUGINS variable in TWikiPreferences. Redefine the DISABLEDPLUGINS variable in the Sandbox web and do the testing there.
Added:
>
>

A Note on Performance

The performance of the system depends on the number of Plugins installed and on the Plugin implementation. Some Plugins impose no measurable performance decrease, some do. For example, outsidePREHandler is an expensive callback function, or a Plugin might use many Perl libraries that needs to be initialized with each page view (unless you run mod_perl). It is recommended to measure the performance with and without a new Plugin.

In case you need to install an "expensive" Plugin and you need its functionality only in one web you can place the Plugin topic into that web. TWiki will initialize the Plugin only if the Plugin topic is found (which won't be the case for other webs.)

 

Managing Plugins

When you finish installing a Plugin, you should be able to read the user instructions and go. In fact, some Plugins require additional settings or offer extra options that you have to select. Also, you may want to make a Plugin available only in certain webs, or temporarily disable it. And may want to list all available Plugins in certain topics. You can handle all of these management tasks with simple procedures.

Setting Preferences

Installed Plugins can be toggled on or off, site-wide or by web, through TWikiPreferences and individual WebPreferences:

  • All Plugin modules present in the lib/TWiki/Plugins directory are activated automatically unless disabled by the DISABLEDPLUGINS Preferences variable in TWikiPreferences. You can optionally list the installed Plugins in the INSTALLEDPLUGINS Preferences variable. This is useful to define the sequence of Plugin execution, or to specify other webs than the TWiki web for the Plugin topics. Settings in TWikiPreferences are:
    • Set INSTALLEDPLUGINS = DefaultPlugin, ...
    • Set DISABLEDPLUGINS = EmptyPlugin, ...

Plugin execution order in TWiki is determined by searching Plugin topics in a specific sequence: First, full web.topicname name, if specified in INSTALLEDPLUGINS; next, the TWiki web is searched; and finally, the current web.

Plugin-specific settings are done in individual Plugin topics. Two settings are standard for each Plugin:

  1. One line description, used to form the bullets describing the Plugins in the TextFormattingRules topic:
    • Set SHORTDESCRIPTION = Blah blah woof woof.
  2. Debug Plugin, output can be seen in data/debug.txt. Set to 0=off or 1=on:
    • Set DEBUG = 0
  • The settings can be retrieved as Preferences variables like %<pluginname>_<var>%, ex: %DEFAULTPLUGIN_SHORTDESCRIPTION% shows the description of the DefaultPlugin.

Listing Active Plugins

Plugin status variables let you list all active Plugins wherever needed. There are two list formats:

  • The %ACTIVATEDPLUGINS% variable lists activated Plugins by name. (This variable is displayed in TWikiPreferences for debugging use.)
  • The %PLUGINDESCRIPTIONS% variable displays a bullet list with a one-line description of each active Plugins. This variable is based on the %<plugin>_SHORTDESCRIPTION% Preferences variables of individual topics and is shown in TextFormattingRules.

DEMO: Automatically List Active Plugins Using Variables

Using %ACTIVATEDPLUGINS%:
On this TWiki site, the active Plugins are: SpreadSheetPlugin, BackupRestorePlugin, ColorPickerPlugin, CommentPlugin, DatePickerPlugin, EditTablePlugin, HeadlinesPlugin, InterwikiPlugin, JQueryPlugin, PreferencesPlugin, SetGetPlugin, SlideShowPlugin, SmiliesPlugin, TWikiSheetPlugin, TablePlugin, TagMePlugin, TinyMCEPlugin, TwistyPlugin, WatchlistPlugin, WysiwygPlugin.

Using %PLUGINDESCRIPTIONS%:
You can use any of these active TWiki Plugins:

  • SpreadSheetPlugin (2018-07-05, $Rev: 30478 (2018-07-16) $): Add spreadsheet calculation like "$SUM( $ABOVE() )" to TWiki tables or anywhere in topic text
  • BackupRestorePlugin (2021-03-19, $Rev: 30914 (2021-03-19) $): Administrator utility to backup, restore and upgrade a TWiki site
  • ColorPickerPlugin (2018-07-05, $Rev: 30442 (2018-07-16) $): Color picker, packaged for use in TWiki forms and TWiki applications
  • CommentPlugin (2018-07-05, $Rev: 30530 (2018-07-16) $): Quickly post comments to a page without an edit/preview/save cycle
  • DatePickerPlugin (2018-07-05, $Rev: 30446 (2018-07-16) $): Pop-up calendar with date picker, for use in TWiki forms, HTML forms and TWiki plugins
  • EditTablePlugin (2018-07-05, $Rev: 30448 (2018-07-16) $): Edit TWiki tables using edit fields, date pickers and drop down boxes
  • HeadlinesPlugin (2018-07-13, $Rev: 30560 (2018-07-16) $): Show headline news in TWiki pages based on RSS and ATOM news feeds from external sites
  • InterwikiPlugin (2018-07-05, $Rev: 30454 (2018-07-16) $): Write ExternalSite:Page to link to a page on an external site based on aliases defined in a rules topic
  • JQueryPlugin (2018-07-05, $Rev: 30456 (2018-07-16) $): jQuery JavaScript library for TWiki
  • PreferencesPlugin (2018-07-05, $Rev: 30528 (2018-07-16) $): Allows editing of preferences using fields predefined in a form
  • SetGetPlugin (2018-07-05, $Rev: 30472 (2018-07-16) $): Set and get variables and JSON objects in topics, optionally persistently across topic views
  • SlideShowPlugin (2018-07-05, $Rev: 30474 (2018-07-16) $): Create web based presentations based on topics with headings.
  • SmiliesPlugin (2018-07-05, $Rev: 30476 (2018-07-16) $): Render smilies as icons, like  :-) for smile or  :eek: for eek!
  • TWikiSheetPlugin (2018-07-15, $Rev: 30604 (2018-07-16) $): Add TWiki Sheet spreadsheet functionality to TWiki tables
  • TablePlugin (2018-07-05, $Rev: 30480 (2018-07-16) $): Control attributes of tables and sorting of table columns
  • TagMePlugin (2018-07-05, $Rev: 30482 (2018-07-16) $): Tag wiki content collectively or authoritatively to find content by keywords
  • TinyMCEPlugin (2021-06-09, $Rev: 31045 (2021-06-09) $): Integration of the Tiny MCE WYSIWYG Editor
  • TwistyPlugin (2018-07-06, $Rev: 30497 (2018-07-16) $): Twisty section JavaScript library to open/close content dynamically
  • WatchlistPlugin (2018-07-10, $Rev: 30536 (2018-07-16) $): Watch topics of interest and get notified of changes by e-mail
  • WysiwygPlugin (2018-07-06, $Rev: 30528 (2018-07-16) $): Translator framework for WYSIWYG editors

The TWiki Plugin API

The Application Programming Interface (API) for TWikiPlugins provides the specifications for hooking into the core TWiki code from your external Perl Plugin module. The Plugin API is new to the Production version of TWiki with the 01-Sep-2001 release.

Available Core Functions

The TWikiFuncModule (lib/TWiki/Func.pm) implements ALL official Plugin functions. Plugins should ONLY use functions published in this module.

ALERT! If you use functions not in Func.pm, you run the risk of creating security holes. Also, your Plugin will likely break and require updating when you upgrade to a new version of TWiki.

Predefined Hooks

In addition to TWiki core functions, Plugins can use predefined hooks, or call backs, listed in the lib/TWiki/Plugins/EmptyPlugin.pm module.

  • All but the initPlugin are disabled. To enable a call back, remove DISABLE_ from the function name.
  • For best performance, enable only the functions you really need. NOTE: outsidePREHandler and insidePREHandler are particularly expensive.

Plugin Version Detection

To eliminate the incompatibility problems bound to arise from active open Plugin development, a Plugin versioning system and an API GetVersion detection routine are provided for automatic compatibility checking.

  • All modules require a $VERSION='0.000' variable, beginning at 1.000.

  • The initPlugin handler should check all dependencies and return TRUE if the initialization is OK or FALSE if something went wrong.
    • The Plugin initialization code does not register a Plugin that returns FALSE (or that has no initPlugin handler).

Creating Plugins

With a reasonable knowledge of the Perl scripting language, you can create new Plugins or modify and extend existing ones. Basic plug-in architecture uses an Application Programming Interface (API), a set of software instructions that allow external code to interact with the main program. The TWiki Plugin API Plugins by providing a programming interface for TWiki.

The DefaultPlugin Alternative

  • DefaultPlugin can handle some outdated TWiki variables, found, for example, in sites recently updated from an old version. Settings are in DefaultPlugin topic. You can also add your own simple custom processing rules here, though in all but very simple cases, writing a new Plugin is preferable.

Anatomy of a Plugin

A basic TWiki Plugin consists of two elements:

  • a Perl module, ex: MyFirstPlugin.pm
  • a documentation topic, ex: MyFirstPlugin.txt

The Perl module can be a block of code that connects with TWiki alone, or it can include other elements, like other Perl modules (including other Plugins), graphics, TWiki templates, external applications (ex: a Java applet), or just about anything else it can call. In particular, files that should be web-accessible (graphics, Java applets ...) are best placed as attachments of the MyFirstPlugin topic. Other needed Perl code is best placed in a lib/TWiki/Plugins/MyFirstPlugin/ directory.

The Plugin API handles the details of connecting your Perl module with main TWiki code. When you're familiar with the Plugin API, you're ready to develop Plugins.

Creating the Perl Module

Copy file lib/TWiki/Plugins/EmptyPlugin.pm to <name>Plugin.pm. The EmptyPlugin.pm module contains mostly empty functions, so it does nothing, but it's ready to be used. Customize it. Refer to the Plugin API specs for more information.

If your Plugin uses its own modules and objects, you must include the name of the Plugin in the package name. For example, write Package MyFirstPlugin::Attrs; instead of just Package Attrs;. Then call it using:

  use TWiki::Plugins::MyFirstPlugin::Attrs;
  $var = MyFirstPlugin::Attrs->new();

Writing the Documentation Topic

The Plugin documentation topic contains usage instructions and version details. It serves the Plugin files as FileAttachments for downloading. (The doc topic is also included in the distribution package.) To create a documentation topic:

  1. Copy the Plugin topic template from TWiki.org. To copy the text, go to TWiki:Plugins/PluginPackage and:
    • enter the Plugin name in the "How to Create a Plugin" section
    • click Create
    • select all in the Edit box & copy
    • Cancel the edit
    • go back to your site to the TWiki web
    • In the GoBox enter your Plugin name, for example MyFirstPlugin, press enter and create the new topic
    • paste & save new Plugin topic on your site
  2. Customize your Plugin topic.
    • In case you plan to publish your Plugin at TWiki.org, use Interwiki names for author names, like TWiki:Main/TWikiGuest.
  3. Save your topic, for use in packaging and publishing your Plugin.

OUTLINE: Doc Topic Contents
Check the Plugins web on TWiki.org for the latest Plugin doc topic template. Here's a quick overview of what's covered:

Syntax Rules: <Describe any special text formatting that will be rendered.>"

Example: <Include an example of the Plugin in action. Possibly include a static HTML version of the example to compare if the installation was a success!>"

Plugin Global Settings: <Description and settings for custom Plugin %VARIABLES%, and those required by TWiki.>"

  • Plugins Preferences <If user settings are needed, explain... Entering values works exactly like TWikiPreferences and WebPreferences: six (6) spaces and then:>"
    • Set <EXAMPLE = value added>

Plugin Installation Instructions: <Step-by-step set-up guide, user help, whatever it takes to install and run, goes here.>"

Plugin Info: <Version, credits, history, requirements - entered in a form, displayed as a table. Both are automatically generated when you create or edit a page in the TWiki:Plugins web.>"

Packaging for Distribution

A minimum Plugin release consists of a Perl module with a WikiName that ends in Plugin, ex: MyFirstPlugin.pm, and a documentation page with the same name(MyFirstPlugin.txt).

  1. Distribute the Plugin files in a directory structure that mirrors TWiki. If your Plugin uses additional files, include them ALL:
    • lib/TWiki/Plugins/MyFirstPlugin.pm
    • data/TWiki/MyFirstPlugin.txt
    • pub/TWiki/MyFirstPlugin/uparrow.gif [a required graphic]
  2. Create a zip archive with the Plugin name (MyFirstPlugin.zip) and add the entire directory structure from Step 1. The archive should look like this:
    • lib/TWiki/Plugins/MyFirstPlugin.pm
    • data/TWiki/MyFirstPlugin.txt
    • pub/TWiki/MyFirstPlugin/uparrow.gif

Publishing for Public Use

You can release your tested, packaged Plugin to the TWiki community through the TWiki:Plugins web. All Plugins submitted to TWiki.org are available for download and further development in TWiki:Plugins. Publish your Plugin in three steps:

  1. Post the Plugin documentation topic in the TWiki:Plugins web:
  2. Attach the distribution zip file to the topic, ex: MyFirstPlugin.zip
  3. Link from the doc page to a new, blank page named after the Plugin, and ending in Dev, ex: MyFirstPluginDev. This is the discussion page for future development. (User support for Plugins is handled in TWiki:Support.)

-- AndreaSterbini - 29 May 2001
-- PeterThoeny - 29 Jan 2003
-- MikeMannix - 03 Dec 2001

Revision 222003-02-28 - PeterThoeny

 

TWiki Plugins

Plug-in enhanced feature add-ons, with a Plugin API for developers

Overview

You can add Plugins to extend TWiki's functionality, without altering the core program code. A plug-in approach lets you:

  • add virtually unlimited features while keeping the main TWiki code compact and efficient;
  • heavily customize an installation and still do clean updates to new versions of TWiki;
  • rapidly develop new TWiki functions in Perl using the Plugin API.

Everything to do with TWiki Plugins - demos, new releases, downloads, development, general discussion - is available at TWiki.org, in the TWiki:Plugins web.

Preinstalled Plugins

TWiki comes with three Plugins as part of the standard installation.

  • DefaultPlugin optionally handles some legacy variables from older versions of TWiki. You can control this option from TWikiPreferences. (Perl programmers can also add rules for simple custom processing.)

  • EmptyPlugin is a fully functional module, minus active code; it does nothing and serves as a template for new Plugin development.

  • InterwikiPlugin is preinstalled but can be disabled or removed. Use it for shorthand linking to remote sites, ex: TWiki:Plugins expands to TWiki:Plugins on TWiki.org. You can edit the predefined set of of Wiki-related sites, and add your own.

Installing Plugins

Each TWikiPlugin comes with full documentation: step-by-step installation instructions, a detailed description of any special requirements, version details, and a working example for testing.

Most Plugins can be installed in three easy steps, with no programming skills required:

  1. Download the zip file containing the Plugin, documentation, and any other required files, from TWiki:Plugins.
  2. Distribute the files to their proper locations - unzip the zip archive in your TWiki installation directory - if have a standard TWiki installation, this will distribute automatically. Otherwise, place the files according to the directory paths listed on the Plugin top in TWiki:Plugins.
  3. Check the demo example on the Plugin topic: if it's working, the installation was fine!

Special Requests: Some Plugins need certain Perl modules to be preinstalled on the host system. Plugins may also use other resources, like graphics, other modules, applications, templates. In these cases, detailed instructions are in the Plugin documentation.

Each Plugin has a standard release page, located in the TWiki:Plugins web at TWiki.org. In addition to the documentation topic (SomePlugin), there's a separate development page.

  • Doc page: Read all available info about the Plugin; download the attached distribution files.
  • Dev page: Post feature requests, bug reports and general dev comments; topic title ends in Dev (SomePluginDev).
  • User support: Post installation, how to use type questions (and answers, if you have them) in the TWiki:Support web.

On-Site Pretesting

To test new Plugins on your installation before making them public, you may want to use one of these two approaches:

  • Method 1: Safely test on-the-fly by creating separate Production and Test branches in your live TWiki installation.
Changed:
<
<
    • Duplicate the twiki/bin and twiki/lib directories for the Test version, adjusting the paths in the new lib/TWiki.cfg, the twiki/data; the twiki/templates and twiki/pub directories are shared.
>
>
    • Duplicate the twiki/bin and twiki/lib directories for the Test version, and adjust the paths in the new lib/TWiki.cfg. The following directories are shared: twiki/data, twiki/templates and twiki/pub.
 
    • Test Plugins and other new features in the Test installation until you're satisfied.
      • ALERT! If you modify topics using the new features, live users will likely see unfamiliar new META tags showing up on their pages - to avoid this, create and edit test-only topics to try out new features.
    • Copy the modified files to the Production installation. You can update a TWiki installation live and users won't even notice.

  • Method 2: List the Plugin being tested in the DISABLEDPLUGINS variable in TWikiPreferences. Redefine the DISABLEDPLUGINS variable in the Sandbox web and do the testing there.

Managing Plugins

When you finish installing a Plugin, you should be able to read the user instructions and go. In fact, some Plugins require additional settings or offer extra options that you have to select. Also, you may want to make a Plugin available only in certain webs, or temporarily disable it. And may want to list all available Plugins in certain topics. You can handle all of these management tasks with simple procedures.

Setting Preferences

Installed Plugins can be toggled on or off, site-wide or by web, through TWikiPreferences and individual WebPreferences:

  • All Plugin modules present in the lib/TWiki/Plugins directory are activated automatically unless disabled by the DISABLEDPLUGINS Preferences variable in TWikiPreferences. You can optionally list the installed Plugins in the INSTALLEDPLUGINS Preferences variable. This is useful to define the sequence of Plugin execution, or to specify other webs than the TWiki web for the Plugin topics. Settings in TWikiPreferences are:
    • Set INSTALLEDPLUGINS = DefaultPlugin, ...
    • Set DISABLEDPLUGINS = EmptyPlugin, ...

Plugin execution order in TWiki is determined by searching Plugin topics in a specific sequence: First, full web.topicname name, if specified in INSTALLEDPLUGINS; next, the TWiki web is searched; and finally, the current web.

Plugin-specific settings are done in individual Plugin topics. Two settings are standard for each Plugin:

  1. One line description, used to form the bullets describing the Plugins in the TextFormattingRules topic:
    • Set SHORTDESCRIPTION = Blah blah woof woof.
  2. Debug Plugin, output can be seen in data/debug.txt. Set to 0=off or 1=on:
    • Set DEBUG = 0
  • The settings can be retrieved as Preferences variables like %<pluginname>_<var>%, ex: %DEFAULTPLUGIN_SHORTDESCRIPTION% shows the description of the DefaultPlugin.

Listing Active Plugins

Plugin status variables let you list all active Plugins wherever needed. There are two list formats:

  • The %ACTIVATEDPLUGINS% variable lists activated Plugins by name. (This variable is displayed in TWikiPreferences for debugging use.)
  • The %PLUGINDESCRIPTIONS% variable displays a bullet list with a one-line description of each active Plugins. This variable is based on the %<plugin>_SHORTDESCRIPTION% Preferences variables of individual topics and is shown in TextFormattingRules.

DEMO: Automatically List Active Plugins Using Variables

Using %ACTIVATEDPLUGINS%:
On this TWiki site, the active Plugins are: SpreadSheetPlugin, BackupRestorePlugin, ColorPickerPlugin, CommentPlugin, DatePickerPlugin, EditTablePlugin, HeadlinesPlugin, InterwikiPlugin, JQueryPlugin, PreferencesPlugin, SetGetPlugin, SlideShowPlugin, SmiliesPlugin, TWikiSheetPlugin, TablePlugin, TagMePlugin, TinyMCEPlugin, TwistyPlugin, WatchlistPlugin, WysiwygPlugin.

Using %PLUGINDESCRIPTIONS%:
You can use any of these active TWiki Plugins:

  • SpreadSheetPlugin (2018-07-05, $Rev: 30478 (2018-07-16) $): Add spreadsheet calculation like "$SUM( $ABOVE() )" to TWiki tables or anywhere in topic text
  • BackupRestorePlugin (2021-03-19, $Rev: 30914 (2021-03-19) $): Administrator utility to backup, restore and upgrade a TWiki site
  • ColorPickerPlugin (2018-07-05, $Rev: 30442 (2018-07-16) $): Color picker, packaged for use in TWiki forms and TWiki applications
  • CommentPlugin (2018-07-05, $Rev: 30530 (2018-07-16) $): Quickly post comments to a page without an edit/preview/save cycle
  • DatePickerPlugin (2018-07-05, $Rev: 30446 (2018-07-16) $): Pop-up calendar with date picker, for use in TWiki forms, HTML forms and TWiki plugins
  • EditTablePlugin (2018-07-05, $Rev: 30448 (2018-07-16) $): Edit TWiki tables using edit fields, date pickers and drop down boxes
  • HeadlinesPlugin (2018-07-13, $Rev: 30560 (2018-07-16) $): Show headline news in TWiki pages based on RSS and ATOM news feeds from external sites
  • InterwikiPlugin (2018-07-05, $Rev: 30454 (2018-07-16) $): Write ExternalSite:Page to link to a page on an external site based on aliases defined in a rules topic
  • JQueryPlugin (2018-07-05, $Rev: 30456 (2018-07-16) $): jQuery JavaScript library for TWiki
  • PreferencesPlugin (2018-07-05, $Rev: 30528 (2018-07-16) $): Allows editing of preferences using fields predefined in a form
  • SetGetPlugin (2018-07-05, $Rev: 30472 (2018-07-16) $): Set and get variables and JSON objects in topics, optionally persistently across topic views
  • SlideShowPlugin (2018-07-05, $Rev: 30474 (2018-07-16) $): Create web based presentations based on topics with headings.
  • SmiliesPlugin (2018-07-05, $Rev: 30476 (2018-07-16) $): Render smilies as icons, like  :-) for smile or  :eek: for eek!
  • TWikiSheetPlugin (2018-07-15, $Rev: 30604 (2018-07-16) $): Add TWiki Sheet spreadsheet functionality to TWiki tables
  • TablePlugin (2018-07-05, $Rev: 30480 (2018-07-16) $): Control attributes of tables and sorting of table columns
  • TagMePlugin (2018-07-05, $Rev: 30482 (2018-07-16) $): Tag wiki content collectively or authoritatively to find content by keywords
  • TinyMCEPlugin (2021-06-09, $Rev: 31045 (2021-06-09) $): Integration of the Tiny MCE WYSIWYG Editor
  • TwistyPlugin (2018-07-06, $Rev: 30497 (2018-07-16) $): Twisty section JavaScript library to open/close content dynamically
  • WatchlistPlugin (2018-07-10, $Rev: 30536 (2018-07-16) $): Watch topics of interest and get notified of changes by e-mail
  • WysiwygPlugin (2018-07-06, $Rev: 30528 (2018-07-16) $): Translator framework for WYSIWYG editors

The TWiki Plugin API

The Application Programming Interface (API) for TWikiPlugins provides the specifications for hooking into the core TWiki code from your external Perl Plugin module. The Plugin API is new to the Production version of TWiki with the 01-Sep-2001 release.

Available Core Functions

The TWikiFuncModule (lib/TWiki/Func.pm) implements ALL official Plugin functions. Plugins should ONLY use functions published in this module.

ALERT! If you use functions not in Func.pm, you run the risk of creating security holes. Also, your Plugin will likely break and require updating when you upgrade to a new version of TWiki.

Predefined Hooks

In addition to TWiki core functions, Plugins can use predefined hooks, or call backs, listed in the lib/TWiki/Plugins/EmptyPlugin.pm module.

  • All but the initPlugin are disabled. To enable a call back, remove DISABLE_ from the function name.
  • For best performance, enable only the functions you really need. NOTE: outsidePREHandler and insidePREHandler are particularly expensive.

Plugin Version Detection

To eliminate the incompatibility problems bound to arise from active open Plugin development, a Plugin versioning system and an API GetVersion detection routine are provided for automatic compatibility checking.

  • All modules require a $VERSION='0.000' variable, beginning at 1.000.

  • The initPlugin handler should check all dependencies and return TRUE if the initialization is OK or FALSE if something went wrong.
    • The Plugin initialization code does not register a Plugin that returns FALSE (or that has no initPlugin handler).

Creating Plugins

With a reasonable knowledge of the Perl scripting language, you can create new Plugins or modify and extend existing ones. Basic plug-in architecture uses an Application Programming Interface (API), a set of software instructions that allow external code to interact with the main program. The TWiki Plugin API Plugins by providing a programming interface for TWiki.

The DefaultPlugin Alternative

  • DefaultPlugin can handle some outdated TWiki variables, found, for example, in sites recently updated from an old version. Settings are in DefaultPlugin topic. You can also add your own simple custom processing rules here, though in all but very simple cases, writing a new Plugin is preferable.

Anatomy of a Plugin

A basic TWiki Plugin consists of two elements:

  • a Perl module, ex: MyFirstPlugin.pm
  • a documentation topic, ex: MyFirstPlugin.txt

The Perl module can be a block of code that connects with TWiki alone, or it can include other elements, like other Perl modules (including other Plugins), graphics, TWiki templates, external applications (ex: a Java applet), or just about anything else it can call. In particular, files that should be web-accessible (graphics, Java applets ...) are best placed as attachments of the MyFirstPlugin topic. Other needed Perl code is best placed in a lib/TWiki/Plugins/MyFirstPlugin/ directory.

The Plugin API handles the details of connecting your Perl module with main TWiki code. When you're familiar with the Plugin API, you're ready to develop Plugins.

Creating the Perl Module

Copy file lib/TWiki/Plugins/EmptyPlugin.pm to <name>Plugin.pm. The EmptyPlugin.pm module contains mostly empty functions, so it does nothing, but it's ready to be used. Customize it. Refer to the Plugin API specs for more information.

If your Plugin uses its own modules and objects, you must include the name of the Plugin in the package name. For example, write Package MyFirstPlugin::Attrs; instead of just Package Attrs;. Then call it using:

  use TWiki::Plugins::MyFirstPlugin::Attrs;
  $var = MyFirstPlugin::Attrs->new();

Writing the Documentation Topic

The Plugin documentation topic contains usage instructions and version details. It serves the Plugin files as FileAttachments for downloading. (The doc topic is also included in the distribution package.) To create a documentation topic:

  1. Copy the Plugin topic template from TWiki.org. To copy the text, go to TWiki:Plugins/PluginPackage and:
    • enter the Plugin name in the "How to Create a Plugin" section
    • click Create
    • select all in the Edit box & copy
    • Cancel the edit
    • go back to your site to the TWiki web
    • In the GoBox enter your Plugin name, for example MyFirstPlugin, press enter and create the new topic
    • paste & save new Plugin topic on your site
  2. Customize your Plugin topic.
    • In case you plan to publish your Plugin at TWiki.org, use Interwiki names for author names, like TWiki:Main/TWikiGuest.
  3. Save your topic, for use in packaging and publishing your Plugin.

OUTLINE: Doc Topic Contents
Check the Plugins web on TWiki.org for the latest Plugin doc topic template. Here's a quick overview of what's covered:

Syntax Rules: <Describe any special text formatting that will be rendered.>"

Example: <Include an example of the Plugin in action. Possibly include a static HTML version of the example to compare if the installation was a success!>"

Plugin Global Settings: <Description and settings for custom Plugin %VARIABLES%, and those required by TWiki.>"

  • Plugins Preferences <If user settings are needed, explain... Entering values works exactly like TWikiPreferences and WebPreferences: six (6) spaces and then:>"
    • Set <EXAMPLE = value added>

Plugin Installation Instructions: <Step-by-step set-up guide, user help, whatever it takes to install and run, goes here.>"

Plugin Info: <Version, credits, history, requirements - entered in a form, displayed as a table. Both are automatically generated when you create or edit a page in the TWiki:Plugins web.>"

Packaging for Distribution

A minimum Plugin release consists of a Perl module with a WikiName that ends in Plugin, ex: MyFirstPlugin.pm, and a documentation page with the same name(MyFirstPlugin.txt).

  1. Distribute the Plugin files in a directory structure that mirrors TWiki. If your Plugin uses additional files, include them ALL:
    • lib/TWiki/Plugins/MyFirstPlugin.pm
    • data/TWiki/MyFirstPlugin.txt
    • pub/TWiki/MyFirstPlugin/uparrow.gif [a required graphic]
  2. Create a zip archive with the Plugin name (MyFirstPlugin.zip) and add the entire directory structure from Step 1. The archive should look like this:
    • lib/TWiki/Plugins/MyFirstPlugin.pm
    • data/TWiki/MyFirstPlugin.txt
    • pub/TWiki/MyFirstPlugin/uparrow.gif

Publishing for Public Use

You can release your tested, packaged Plugin to the TWiki community through the TWiki:Plugins web. All Plugins submitted to TWiki.org are available for download and further development in TWiki:Plugins. Publish your Plugin in three steps:

  1. Post the Plugin documentation topic in the TWiki:Plugins web:
  2. Attach the distribution zip file to the topic, ex: MyFirstPlugin.zip
  3. Link from the doc page to a new, blank page named after the Plugin, and ending in Dev, ex: MyFirstPluginDev. This is the discussion page for future development. (User support for Plugins is handled in TWiki:Support.)

-- AndreaSterbini - 29 May 2001
-- PeterThoeny - 29 Jan 2003
-- MikeMannix - 03 Dec 2001

Revision 212003-01-29 - PeterThoeny

 

TWiki Plugins

Plug-in enhanced feature add-ons, with a Plugin API for developers

Overview

You can add Plugins to extend TWiki's functionality, without altering the core program code. A plug-in approach lets you:

  • add virtually unlimited features while keeping the main TWiki code compact and efficient;
  • heavily customize an installation and still do clean updates to new versions of TWiki;
  • rapidly develop new TWiki functions in Perl using the Plugin API.

Everything to do with TWiki Plugins - demos, new releases, downloads, development, general discussion - is available at TWiki.org, in the TWiki:Plugins web.

Preinstalled Plugins

TWiki comes with three Plugins as part of the standard installation.

  • DefaultPlugin optionally handles some legacy variables from older versions of TWiki. You can control this option from TWikiPreferences. (Perl programmers can also add rules for simple custom processing.)

  • EmptyPlugin is a fully functional module, minus active code; it does nothing and serves as a template for new Plugin development.

  • InterwikiPlugin is preinstalled but can be disabled or removed. Use it for shorthand linking to remote sites, ex: TWiki:Plugins expands to TWiki:Plugins on TWiki.org. You can edit the predefined set of of Wiki-related sites, and add your own.

Installing Plugins

Each TWikiPlugin comes with full documentation: step-by-step installation instructions, a detailed description of any special requirements, version details, and a working example for testing.

Most Plugins can be installed in three easy steps, with no programming skills required:

  1. Download the zip file containing the Plugin, documentation, and any other required files, from TWiki:Plugins.
  2. Distribute the files to their proper locations - unzip the zip archive in your TWiki installation directory - if have a standard TWiki installation, this will distribute automatically. Otherwise, place the files according to the directory paths listed on the Plugin top in TWiki:Plugins.
  3. Check the demo example on the Plugin topic: if it's working, the installation was fine!

Special Requests: Some Plugins need certain Perl modules to be preinstalled on the host system. Plugins may also use other resources, like graphics, other modules, applications, templates. In these cases, detailed instructions are in the Plugin documentation.

Each Plugin has a standard release page, located in the TWiki:Plugins web at TWiki.org. In addition to the documentation topic (SomePlugin), there's a separate development page.

  • Doc page: Read all available info about the Plugin; download the attached distribution files.
  • Dev page: Post feature requests, bug reports and general dev comments; topic title ends in Dev (SomePluginDev).
  • User support: Post installation, how to use type questions (and answers, if you have them) in the TWiki:Support web.

On-Site Pretesting

To test new Plugins on your installation before making them public, you may want to use one of these two approaches:

  • Method 1: Safely test on-the-fly by creating separate Production and Test branches in your live TWiki installation.
    • Duplicate the twiki/bin and twiki/lib directories for the Test version, adjusting the paths in the new lib/TWiki.cfg, the twiki/data; the twiki/templates and twiki/pub directories are shared.
    • Test Plugins and other new features in the Test installation until you're satisfied.
      • ALERT! If you modify topics using the new features, live users will likely see unfamiliar new META tags showing up on their pages - to avoid this, create and edit test-only topics to try out new features.
    • Copy the modified files to the Production installation. You can update a TWiki installation live and users won't even notice.

  • Method 2: List the Plugin being tested in the DISABLEDPLUGINS variable in TWikiPreferences. Redefine the DISABLEDPLUGINS variable in the Sandbox web and do the testing there.

Managing Plugins

When you finish installing a Plugin, you should be able to read the user instructions and go. In fact, some Plugins require additional settings or offer extra options that you have to select. Also, you may want to make a Plugin available only in certain webs, or temporarily disable it. And may want to list all available Plugins in certain topics. You can handle all of these management tasks with simple procedures.

Setting Preferences

Installed Plugins can be toggled on or off, site-wide or by web, through TWikiPreferences and individual WebPreferences:

  • All Plugin modules present in the lib/TWiki/Plugins directory are activated automatically unless disabled by the DISABLEDPLUGINS Preferences variable in TWikiPreferences. You can optionally list the installed Plugins in the INSTALLEDPLUGINS Preferences variable. This is useful to define the sequence of Plugin execution, or to specify other webs than the TWiki web for the Plugin topics. Settings in TWikiPreferences are:
    • Set INSTALLEDPLUGINS = DefaultPlugin, ...
    • Set DISABLEDPLUGINS = EmptyPlugin, ...

Plugin execution order in TWiki is determined by searching Plugin topics in a specific sequence: First, full web.topicname name, if specified in INSTALLEDPLUGINS; next, the TWiki web is searched; and finally, the current web.

Plugin-specific settings are done in individual Plugin topics. Two settings are standard for each Plugin:

  1. One line description, used to form the bullets describing the Plugins in the TextFormattingRules topic:
    • Set SHORTDESCRIPTION = Blah blah woof woof.
  2. Debug Plugin, output can be seen in data/debug.txt. Set to 0=off or 1=on:
    • Set DEBUG = 0
  • The settings can be retrieved as Preferences variables like %<pluginname>_<var>%, ex: %DEFAULTPLUGIN_SHORTDESCRIPTION% shows the description of the DefaultPlugin.

Listing Active Plugins

Plugin status variables let you list all active Plugins wherever needed. There are two list formats:

  • The %ACTIVATEDPLUGINS% variable lists activated Plugins by name. (This variable is displayed in TWikiPreferences for debugging use.)
  • The %PLUGINDESCRIPTIONS% variable displays a bullet list with a one-line description of each active Plugins. This variable is based on the %<plugin>_SHORTDESCRIPTION% Preferences variables of individual topics and is shown in TextFormattingRules.

DEMO: Automatically List Active Plugins Using Variables

Using %ACTIVATEDPLUGINS%:
On this TWiki site, the active Plugins are: SpreadSheetPlugin, BackupRestorePlugin, ColorPickerPlugin, CommentPlugin, DatePickerPlugin, EditTablePlugin, HeadlinesPlugin, InterwikiPlugin, JQueryPlugin, PreferencesPlugin, SetGetPlugin, SlideShowPlugin, SmiliesPlugin, TWikiSheetPlugin, TablePlugin, TagMePlugin, TinyMCEPlugin, TwistyPlugin, WatchlistPlugin, WysiwygPlugin.

Using %PLUGINDESCRIPTIONS%:
You can use any of these active TWiki Plugins:

  • SpreadSheetPlugin (2018-07-05, $Rev: 30478 (2018-07-16) $): Add spreadsheet calculation like "$SUM( $ABOVE() )" to TWiki tables or anywhere in topic text
  • BackupRestorePlugin (2021-03-19, $Rev: 30914 (2021-03-19) $): Administrator utility to backup, restore and upgrade a TWiki site
  • ColorPickerPlugin (2018-07-05, $Rev: 30442 (2018-07-16) $): Color picker, packaged for use in TWiki forms and TWiki applications
  • CommentPlugin (2018-07-05, $Rev: 30530 (2018-07-16) $): Quickly post comments to a page without an edit/preview/save cycle
  • DatePickerPlugin (2018-07-05, $Rev: 30446 (2018-07-16) $): Pop-up calendar with date picker, for use in TWiki forms, HTML forms and TWiki plugins
  • EditTablePlugin (2018-07-05, $Rev: 30448 (2018-07-16) $): Edit TWiki tables using edit fields, date pickers and drop down boxes
  • HeadlinesPlugin (2018-07-13, $Rev: 30560 (2018-07-16) $): Show headline news in TWiki pages based on RSS and ATOM news feeds from external sites
  • InterwikiPlugin (2018-07-05, $Rev: 30454 (2018-07-16) $): Write ExternalSite:Page to link to a page on an external site based on aliases defined in a rules topic
  • JQueryPlugin (2018-07-05, $Rev: 30456 (2018-07-16) $): jQuery JavaScript library for TWiki
  • PreferencesPlugin (2018-07-05, $Rev: 30528 (2018-07-16) $): Allows editing of preferences using fields predefined in a form
  • SetGetPlugin (2018-07-05, $Rev: 30472 (2018-07-16) $): Set and get variables and JSON objects in topics, optionally persistently across topic views
  • SlideShowPlugin (2018-07-05, $Rev: 30474 (2018-07-16) $): Create web based presentations based on topics with headings.
  • SmiliesPlugin (2018-07-05, $Rev: 30476 (2018-07-16) $): Render smilies as icons, like  :-) for smile or  :eek: for eek!
  • TWikiSheetPlugin (2018-07-15, $Rev: 30604 (2018-07-16) $): Add TWiki Sheet spreadsheet functionality to TWiki tables
  • TablePlugin (2018-07-05, $Rev: 30480 (2018-07-16) $): Control attributes of tables and sorting of table columns
  • TagMePlugin (2018-07-05, $Rev: 30482 (2018-07-16) $): Tag wiki content collectively or authoritatively to find content by keywords
  • TinyMCEPlugin (2021-06-09, $Rev: 31045 (2021-06-09) $): Integration of the Tiny MCE WYSIWYG Editor
  • TwistyPlugin (2018-07-06, $Rev: 30497 (2018-07-16) $): Twisty section JavaScript library to open/close content dynamically
  • WatchlistPlugin (2018-07-10, $Rev: 30536 (2018-07-16) $): Watch topics of interest and get notified of changes by e-mail
  • WysiwygPlugin (2018-07-06, $Rev: 30528 (2018-07-16) $): Translator framework for WYSIWYG editors

The TWiki Plugin API

The Application Programming Interface (API) for TWikiPlugins provides the specifications for hooking into the core TWiki code from your external Perl Plugin module. The Plugin API is new to the Production version of TWiki with the 01-Sep-2001 release.

Available Core Functions

The TWikiFuncModule (lib/TWiki/Func.pm) implements ALL official Plugin functions. Plugins should ONLY use functions published in this module.

ALERT! If you use functions not in Func.pm, you run the risk of creating security holes. Also, your Plugin will likely break and require updating when you upgrade to a new version of TWiki.

Predefined Hooks

In addition to TWiki core functions, Plugins can use predefined hooks, or call backs, listed in the lib/TWiki/Plugins/EmptyPlugin.pm module.

Deleted:
<
<
  • For best performance, enable only the functions you really need. NOTE: outsidePREHandler and insidePREHandler are particularly expensive.
 
  • All but the initPlugin are disabled. To enable a call back, remove DISABLE_ from the function name.
Added:
>
>
  • For best performance, enable only the functions you really need. NOTE: outsidePREHandler and insidePREHandler are particularly expensive.
 

Plugin Version Detection

To eliminate the incompatibility problems bound to arise from active open Plugin development, a Plugin versioning system and an API GetVersion detection routine are provided for automatic compatibility checking.

  • All modules require a $VERSION='0.000' variable, beginning at 1.000.

  • The initPlugin handler should check all dependencies and return TRUE if the initialization is OK or FALSE if something went wrong.
    • The Plugin initialization code does not register a Plugin that returns FALSE (or that has no initPlugin handler).

Creating Plugins

With a reasonable knowledge of the Perl scripting language, you can create new Plugins or modify and extend existing ones. Basic plug-in architecture uses an Application Programming Interface (API), a set of software instructions that allow external code to interact with the main program. The TWiki Plugin API Plugins by providing a programming interface for TWiki.

The DefaultPlugin Alternative

  • DefaultPlugin can handle some outdated TWiki variables, found, for example, in sites recently updated from an old version. Settings are in DefaultPlugin topic. You can also add your own simple custom processing rules here, though in all but very simple cases, writing a new Plugin is preferable.

Anatomy of a Plugin

A basic TWiki Plugin consists of two elements:

  • a Perl module, ex: MyFirstPlugin.pm
  • a documentation topic, ex: MyFirstPlugin.txt

The Perl module can be a block of code that connects with TWiki alone, or it can include other elements, like other Perl modules (including other Plugins), graphics, TWiki templates, external applications (ex: a Java applet), or just about anything else it can call. In particular, files that should be web-accessible (graphics, Java applets ...) are best placed as attachments of the MyFirstPlugin topic. Other needed Perl code is best placed in a lib/TWiki/Plugins/MyFirstPlugin/ directory.

The Plugin API handles the details of connecting your Perl module with main TWiki code. When you're familiar with the Plugin API, you're ready to develop Plugins.

Creating the Perl Module

Changed:
<
<
Copy file lib/TWiki/Plugins/EmptyPlugin.pm to <name>Plugin.pm. EmptyPlugin.pm contains no executable code, so it does nothing, but it's ready to be used. Customize it. Refer to the Plugin API specs for more information.
>
>
Copy file lib/TWiki/Plugins/EmptyPlugin.pm to <name>Plugin.pm. The EmptyPlugin.pm module contains mostly empty functions, so it does nothing, but it's ready to be used. Customize it. Refer to the Plugin API specs for more information.
 
Added:
>
>
If your Plugin uses its own modules and objects, you must include the name of the Plugin in the package name. For example, write Package MyFirstPlugin::Attrs; instead of just Package Attrs;. Then call it using:
  use TWiki::Plugins::MyFirstPlugin::Attrs;
  $var = MyFirstPlugin::Attrs->new();
 

Writing the Documentation Topic

The Plugin documentation topic contains usage instructions and version details. It serves the Plugin files as FileAttachments for downloading. (The doc topic is also included in the distribution package.) To create a documentation topic:

Changed:
<
<
  1. Copy the Plugin topic template from EmptyPlugin. To copy the text, go to the page and:
    • click Edit
    • select all in the Edit box & copy
>
>
  1. Copy the Plugin topic template from TWiki.org. To copy the text, go to TWiki:Plugins/PluginPackage and:
    • enter the Plugin name in the "How to Create a Plugin" section
    • click Create
Added:
>
>
    • select all in the Edit box & copy
 
    • Cancel the edit
Changed:
<
<
    • paste & save as a text file or new topic on your site
  1. Customize the template for your Plugin; you'll probably want to post a working version on your local TWiki site.
  2. Save your topic as a text file, for use in packaging and publishing your Plugin.
>
>
    • go back to your site to the TWiki web
    • In the GoBox enter your Plugin name, for example MyFirstPlugin, press enter and create the new topic
    • paste & save new Plugin topic on your site
Added:
>
>
  1. Customize your Plugin topic.
    • In case you plan to publish your Plugin at TWiki.org, use Interwiki names for author names, like TWiki:Main/TWikiGuest.
  2. Save your topic, for use in packaging and publishing your Plugin.
 
OUTLINE: Doc Topic Contents
Changed:
<
<
Check EmptyPlugin on TWiki.org for the latest Plugin doc topic template. Here's a quick overview of what's covered:
>
>
Check the Plugins web on TWiki.org for the latest Plugin doc topic template. Here's a quick overview of what's covered:
  Syntax Rules: <Describe any special text formatting that will be rendered.>"
Changed:
<
<
MyFirstPlugin Settings: <Description and settings for custom Plugin %VARIABLES%, and those required by TWiki.>"
>
>
Example: <Include an example of the Plugin in action. Possibly include a static HTML version of the example to compare if the installation was a success!>"
 
Changed:
<
<
  • Plugins Preferences <If user settings are needed, explain... Entering valuse works exactly like TWikiPreferences and WebPreferences: six (6) spaces and then:>"
>
>
Plugin Global Settings: <Description and settings for custom Plugin %VARIABLES%, and those required by TWiki.>"
Added:
>
>
  • Plugins Preferences <If user settings are needed, explain... Entering values works exactly like TWikiPreferences and WebPreferences: six (6) spaces and then:>"
 
    • Set <EXAMPLE = value added>
Changed:
<
<
How-to Instructions: <Step-by-step set-up guide, user help, whatever it takes to install and run, goes here.>"
>
>
Plugin Installation Instructions: <Step-by-step set-up guide, user help, whatever it takes to install and run, goes here.>"
 
Deleted:
<
<
Test Example: <Include an example of the Plugin in action: if it works, the installation was a success!>"
 Plugin Info: <Version, credits, history, requirements - entered in a form, displayed as a table. Both are automatically generated when you create or edit a page in the TWiki:Plugins web.>"

Packaging for Distribution

A minimum Plugin release consists of a Perl module with a WikiName that ends in Plugin, ex: MyFirstPlugin.pm, and a documentation page with the same name(MyFirstPlugin.txt).

  1. Distribute the Plugin files in a directory structure that mirrors TWiki. If your Plugin uses additional files, include them ALL:
    • lib/TWiki/Plugins/MyFirstPlugin.pm
    • data/TWiki/MyFirstPlugin.txt
    • pub/TWiki/MyFirstPlugin/uparrow.gif [a required graphic]
  2. Create a zip archive with the Plugin name (MyFirstPlugin.zip) and add the entire directory structure from Step 1. The archive should look like this:
    • lib/TWiki/Plugins/MyFirstPlugin.pm
    • data/TWiki/MyFirstPlugin.txt
    • pub/TWiki/MyFirstPlugin/uparrow.gif

Publishing for Public Use

You can release your tested, packaged Plugin to the TWiki community through the TWiki:Plugins web. All Plugins submitted to TWiki.org are available for download and further development in TWiki:Plugins. Publish your Plugin in three steps:

  1. Post the Plugin documentation topic in the TWiki:Plugins web:
  2. Attach the distribution zip file to the topic, ex: MyFirstPlugin.zip
  3. Link from the doc page to a new, blank page named after the Plugin, and ending in Dev, ex: MyFirstPluginDev. This is the discussion page for future development. (User support for Plugins is handled in TWiki:Support.)

-- AndreaSterbini - 29 May 2001

Changed:
<
<
-- PeterThoeny - 14 Sep 2001
>
>
-- PeterThoeny - 29 Jan 2003
 -- MikeMannix - 03 Dec 2001

Revision 202002-12-08 - PeterThoeny

 

TWiki Plugins

Plug-in enhanced feature add-ons, with a Plugin API for developers

Overview

You can add Plugins to extend TWiki's functionality, without altering the core program code. A plug-in approach lets you:

  • add virtually unlimited features while keeping the main TWiki code compact and efficient;
  • heavily customize an installation and still do clean updates to new versions of TWiki;
  • rapidly develop new TWiki functions in Perl using the Plugin API.

Everything to do with TWiki Plugins - demos, new releases, downloads, development, general discussion - is available at TWiki.org, in the TWiki:Plugins web.

Preinstalled Plugins

TWiki comes with three Plugins as part of the standard installation.

  • DefaultPlugin optionally handles some legacy variables from older versions of TWiki. You can control this option from TWikiPreferences. (Perl programmers can also add rules for simple custom processing.)

  • EmptyPlugin is a fully functional module, minus active code; it does nothing and serves as a template for new Plugin development.

  • InterwikiPlugin is preinstalled but can be disabled or removed. Use it for shorthand linking to remote sites, ex: TWiki:Plugins expands to TWiki:Plugins on TWiki.org. You can edit the predefined set of of Wiki-related sites, and add your own.

Installing Plugins

Each TWikiPlugin comes with full documentation: step-by-step installation instructions, a detailed description of any special requirements, version details, and a working example for testing.

Most Plugins can be installed in three easy steps, with no programming skills required:

  1. Download the zip file containing the Plugin, documentation, and any other required files, from TWiki:Plugins.
  2. Distribute the files to their proper locations - unzip the zip archive in your TWiki installation directory - if have a standard TWiki installation, this will distribute automatically. Otherwise, place the files according to the directory paths listed on the Plugin top in TWiki:Plugins.
  3. Check the demo example on the Plugin topic: if it's working, the installation was fine!

Special Requests: Some Plugins need certain Perl modules to be preinstalled on the host system. Plugins may also use other resources, like graphics, other modules, applications, templates. In these cases, detailed instructions are in the Plugin documentation.

Each Plugin has a standard release page, located in the TWiki:Plugins web at TWiki.org. In addition to the documentation topic (SomePlugin), there's a separate development page.

  • Doc page: Read all available info about the Plugin; download the attached distribution files.
  • Dev page: Post feature requests, bug reports and general dev comments; topic title ends in Dev (SomePluginDev).
  • User support: Post installation, how to use type questions (and answers, if you have them) in the TWiki:Support web.

On-Site Pretesting

To test new Plugins on your installation before making them public, you may want to use one of these two approaches:

  • Method 1: Safely test on-the-fly by creating separate Production and Test branches in your live TWiki installation.
    • Duplicate the twiki/bin and twiki/lib directories for the Test version, adjusting the paths in the new lib/TWiki.cfg, the twiki/data; the twiki/templates and twiki/pub directories are shared.
    • Test Plugins and other new features in the Test installation until you're satisfied.
      • ALERT! If you modify topics using the new features, live users will likely see unfamiliar new META tags showing up on their pages - to avoid this, create and edit test-only topics to try out new features.
    • Copy the modified files to the Production installation. You can update a TWiki installation live and users won't even notice.

  • Method 2: List the Plugin being tested in the DISABLEDPLUGINS variable in TWikiPreferences. Redefine the DISABLEDPLUGINS variable in the Sandbox web and do the testing there.

Managing Plugins

When you finish installing a Plugin, you should be able to read the user instructions and go. In fact, some Plugins require additional settings or offer extra options that you have to select. Also, you may want to make a Plugin available only in certain webs, or temporarily disable it. And may want to list all available Plugins in certain topics. You can handle all of these management tasks with simple procedures.

Setting Preferences

Installed Plugins can be toggled on or off, site-wide or by web, through TWikiPreferences and individual WebPreferences:

  • All Plugin modules present in the lib/TWiki/Plugins directory are activated automatically unless disabled by the DISABLEDPLUGINS Preferences variable in TWikiPreferences. You can optionally list the installed Plugins in the INSTALLEDPLUGINS Preferences variable. This is useful to define the sequence of Plugin execution, or to specify other webs than the TWiki web for the Plugin topics. Settings in TWikiPreferences are:
    • Set INSTALLEDPLUGINS = DefaultPlugin, ...
    • Set DISABLEDPLUGINS = EmptyPlugin, ...

Plugin execution order in TWiki is determined by searching Plugin topics in a specific sequence: First, full web.topicname name, if specified in INSTALLEDPLUGINS; next, the TWiki web is searched; and finally, the current web.

Plugin-specific settings are done in individual Plugin topics. Two settings are standard for each Plugin:

  1. One line description, used to form the bullets describing the Plugins in the TextFormattingRules topic:
    • Set SHORTDESCRIPTION = Blah blah woof woof.
  2. Debug Plugin, output can be seen in data/debug.txt. Set to 0=off or 1=on:
    • Set DEBUG = 0
  • The settings can be retrieved as Preferences variables like %<pluginname>_<var>%, ex: %DEFAULTPLUGIN_SHORTDESCRIPTION% shows the description of the DefaultPlugin.

Listing Active Plugins

Plugin status variables let you list all active Plugins wherever needed. There are two list formats:

  • The %ACTIVATEDPLUGINS% variable lists activated Plugins by name. (This variable is displayed in TWikiPreferences for debugging use.)
  • The %PLUGINDESCRIPTIONS% variable displays a bullet list with a one-line description of each active Plugins. This variable is based on the %<plugin>_SHORTDESCRIPTION% Preferences variables of individual topics and is shown in TextFormattingRules.

DEMO: Automatically List Active Plugins Using Variables

Using %ACTIVATEDPLUGINS%:
On this TWiki site, the active Plugins are: SpreadSheetPlugin, BackupRestorePlugin, ColorPickerPlugin, CommentPlugin, DatePickerPlugin, EditTablePlugin, HeadlinesPlugin, InterwikiPlugin, JQueryPlugin, PreferencesPlugin, SetGetPlugin, SlideShowPlugin, SmiliesPlugin, TWikiSheetPlugin, TablePlugin, TagMePlugin, TinyMCEPlugin, TwistyPlugin, WatchlistPlugin, WysiwygPlugin.

Using %PLUGINDESCRIPTIONS%:
You can use any of these active TWiki Plugins:

  • SpreadSheetPlugin (2018-07-05, $Rev: 30478 (2018-07-16) $): Add spreadsheet calculation like "$SUM( $ABOVE() )" to TWiki tables or anywhere in topic text
  • BackupRestorePlugin (2021-03-19, $Rev: 30914 (2021-03-19) $): Administrator utility to backup, restore and upgrade a TWiki site
  • ColorPickerPlugin (2018-07-05, $Rev: 30442 (2018-07-16) $): Color picker, packaged for use in TWiki forms and TWiki applications
  • CommentPlugin (2018-07-05, $Rev: 30530 (2018-07-16) $): Quickly post comments to a page without an edit/preview/save cycle
  • DatePickerPlugin (2018-07-05, $Rev: 30446 (2018-07-16) $): Pop-up calendar with date picker, for use in TWiki forms, HTML forms and TWiki plugins
  • EditTablePlugin (2018-07-05, $Rev: 30448 (2018-07-16) $): Edit TWiki tables using edit fields, date pickers and drop down boxes
  • HeadlinesPlugin (2018-07-13, $Rev: 30560 (2018-07-16) $): Show headline news in TWiki pages based on RSS and ATOM news feeds from external sites
  • InterwikiPlugin (2018-07-05, $Rev: 30454 (2018-07-16) $): Write ExternalSite:Page to link to a page on an external site based on aliases defined in a rules topic
  • JQueryPlugin (2018-07-05, $Rev: 30456 (2018-07-16) $): jQuery JavaScript library for TWiki
  • PreferencesPlugin (2018-07-05, $Rev: 30528 (2018-07-16) $): Allows editing of preferences using fields predefined in a form
  • SetGetPlugin (2018-07-05, $Rev: 30472 (2018-07-16) $): Set and get variables and JSON objects in topics, optionally persistently across topic views
  • SlideShowPlugin (2018-07-05, $Rev: 30474 (2018-07-16) $): Create web based presentations based on topics with headings.
  • SmiliesPlugin (2018-07-05, $Rev: 30476 (2018-07-16) $): Render smilies as icons, like  :-) for smile or  :eek: for eek!
  • TWikiSheetPlugin (2018-07-15, $Rev: 30604 (2018-07-16) $): Add TWiki Sheet spreadsheet functionality to TWiki tables
  • TablePlugin (2018-07-05, $Rev: 30480 (2018-07-16) $): Control attributes of tables and sorting of table columns
  • TagMePlugin (2018-07-05, $Rev: 30482 (2018-07-16) $): Tag wiki content collectively or authoritatively to find content by keywords
  • TinyMCEPlugin (2021-06-09, $Rev: 31045 (2021-06-09) $): Integration of the Tiny MCE WYSIWYG Editor
  • TwistyPlugin (2018-07-06, $Rev: 30497 (2018-07-16) $): Twisty section JavaScript library to open/close content dynamically
  • WatchlistPlugin (2018-07-10, $Rev: 30536 (2018-07-16) $): Watch topics of interest and get notified of changes by e-mail
  • WysiwygPlugin (2018-07-06, $Rev: 30528 (2018-07-16) $): Translator framework for WYSIWYG editors

The TWiki Plugin API

The Application Programming Interface (API) for TWikiPlugins provides the specifications for hooking into the core TWiki code from your external Perl Plugin module. The Plugin API is new to the Production version of TWiki with the 01-Sep-2001 release.

Available Core Functions

Changed:
<
<
The lib/TWiki/Func.pm implements ALL official Plugin functions. Plugins should ONLY use functions published in this module.
>
>
The TWikiFuncModule (lib/TWiki/Func.pm) implements ALL official Plugin functions. Plugins should ONLY use functions published in this module.
  ALERT! If you use functions not in Func.pm, you run the risk of creating security holes. Also, your Plugin will likely break and require updating when you upgrade to a new version of TWiki.
Deleted:
<
<
  • For best performance, enable only the functions you really need. NOTE: outsidePREHandler and insidePREHandler are particularly expensive.
 

Predefined Hooks

In addition to TWiki core functions, Plugins can use predefined hooks, or call backs, listed in the lib/TWiki/Plugins/EmptyPlugin.pm module.

Added:
>
>
  • For best performance, enable only the functions you really need. NOTE: outsidePREHandler and insidePREHandler are particularly expensive.
 
  • All but the initPlugin are disabled. To enable a call back, remove DISABLE_ from the function name.

Plugin Version Detection

To eliminate the incompatibility problems bound to arise from active open Plugin development, a Plugin versioning system and an API GetVersion detection routine are provided for automatic compatibility checking.

  • All modules require a $VERSION='0.000' variable, beginning at 1.000.

  • The initPlugin handler should check all dependencies and return TRUE if the initialization is OK or FALSE if something went wrong.
    • The Plugin initialization code does not register a Plugin that returns FALSE (or that has no initPlugin handler).

Creating Plugins

With a reasonable knowledge of the Perl scripting language, you can create new Plugins or modify and extend existing ones. Basic plug-in architecture uses an Application Programming Interface (API), a set of software instructions that allow external code to interact with the main program. The TWiki Plugin API Plugins by providing a programming interface for TWiki.

The DefaultPlugin Alternative

  • DefaultPlugin can handle some outdated TWiki variables, found, for example, in sites recently updated from an old version. Settings are in DefaultPlugin topic. You can also add your own simple custom processing rules here, though in all but very simple cases, writing a new Plugin is preferable.

Anatomy of a Plugin

A basic TWiki Plugin consists of two elements:

  • a Perl module, ex: MyFirstPlugin.pm
  • a documentation topic, ex: MyFirstPlugin.txt

The Perl module can be a block of code that connects with TWiki alone, or it can include other elements, like other Perl modules (including other Plugins), graphics, TWiki templates, external applications (ex: a Java applet), or just about anything else it can call. In particular, files that should be web-accessible (graphics, Java applets ...) are best placed as attachments of the MyFirstPlugin topic. Other needed Perl code is best placed in a lib/TWiki/Plugins/MyFirstPlugin/ directory.

The Plugin API handles the details of connecting your Perl module with main TWiki code. When you're familiar with the Plugin API, you're ready to develop Plugins.

Creating the Perl Module

Copy file lib/TWiki/Plugins/EmptyPlugin.pm to <name>Plugin.pm. EmptyPlugin.pm contains no executable code, so it does nothing, but it's ready to be used. Customize it. Refer to the Plugin API specs for more information.

Writing the Documentation Topic

The Plugin documentation topic contains usage instructions and version details. It serves the Plugin files as FileAttachments for downloading. (The doc topic is also included in the distribution package.) To create a documentation topic:

  1. Copy the Plugin topic template from EmptyPlugin. To copy the text, go to the page and:
    • click Edit
    • select all in the Edit box & copy
    • Cancel the edit
    • paste & save as a text file or new topic on your site
  2. Customize the template for your Plugin; you'll probably want to post a working version on your local TWiki site.
  3. Save your topic as a text file, for use in packaging and publishing your Plugin.

OUTLINE: Doc Topic Contents
Check EmptyPlugin on TWiki.org for the latest Plugin doc topic template. Here's a quick overview of what's covered:

Syntax Rules: <Describe any special text formatting that will be rendered.>"

MyFirstPlugin Settings: <Description and settings for custom Plugin %VARIABLES%, and those required by TWiki.>"

  • Plugins Preferences <If user settings are needed, explain... Entering valuse works exactly like TWikiPreferences and WebPreferences: six (6) spaces and then:>"
    • Set <EXAMPLE = value added>

How-to Instructions: <Step-by-step set-up guide, user help, whatever it takes to install and run, goes here.>"

Test Example: <Include an example of the Plugin in action: if it works, the installation was a success!>"

Plugin Info: <Version, credits, history, requirements - entered in a form, displayed as a table. Both are automatically generated when you create or edit a page in the TWiki:Plugins web.>"

Packaging for Distribution

A minimum Plugin release consists of a Perl module with a WikiName that ends in Plugin, ex: MyFirstPlugin.pm, and a documentation page with the same name(MyFirstPlugin.txt).

  1. Distribute the Plugin files in a directory structure that mirrors TWiki. If your Plugin uses additional files, include them ALL:
    • lib/TWiki/Plugins/MyFirstPlugin.pm
    • data/TWiki/MyFirstPlugin.txt
    • pub/TWiki/MyFirstPlugin/uparrow.gif [a required graphic]
  2. Create a zip archive with the Plugin name (MyFirstPlugin.zip) and add the entire directory structure from Step 1. The archive should look like this:
    • lib/TWiki/Plugins/MyFirstPlugin.pm
    • data/TWiki/MyFirstPlugin.txt
    • pub/TWiki/MyFirstPlugin/uparrow.gif

Publishing for Public Use

You can release your tested, packaged Plugin to the TWiki community through the TWiki:Plugins web. All Plugins submitted to TWiki.org are available for download and further development in TWiki:Plugins. Publish your Plugin in three steps:

  1. Post the Plugin documentation topic in the TWiki:Plugins web:
  2. Attach the distribution zip file to the topic, ex: MyFirstPlugin.zip
  3. Link from the doc page to a new, blank page named after the Plugin, and ending in Dev, ex: MyFirstPluginDev. This is the discussion page for future development. (User support for Plugins is handled in TWiki:Support.)

-- AndreaSterbini - 29 May 2001
-- PeterThoeny - 14 Sep 2001
-- MikeMannix - 03 Dec 2001

Revision 192002-07-18 - PeterThoeny

 

TWiki Plugins

Plug-in enhanced feature add-ons, with a Plugin API for developers

Overview

You can add Plugins to extend TWiki's functionality, without altering the core program code. A plug-in approach lets you:

  • add virtually unlimited features while keeping the main TWiki code compact and efficient;
  • heavily customize an installation and still do clean updates to new versions of TWiki;
  • rapidly develop new TWiki functions in Perl using the Plugin API.

Everything to do with TWiki Plugins - demos, new releases, downloads, development, general discussion - is available at TWiki.org, in the TWiki:Plugins web.

Preinstalled Plugins

TWiki comes with three Plugins as part of the standard installation.