RegistryWorkingGroup

Work Package 3 (Rwp03): Metadata Specifications

Contents

Introduction

Scope

A Resource is any entity that can be described and identified in a machine readable manner. With this general statement, a resource can be most anything, including a service or a data collection or something more abstract, such as a standard interface. In this work package, we will:

1. Identify the pertinent information necessary for describing and locating a resource within a registry, satisifying the requirements set forth in RWP02.
2. Provide a basic, extensible data model for describing resources within a registry.
3. Develop an XML schema for rendering descriptions of resources in terms of the resource data model.

Although a resource could be anything, this WP should concentrate on describing high-level entities, such as organizations, data collections, and services; this is referred to as coarse-grain granularity. We should strive to keep the basic resource data model simple, reusing data model components (that might come out of the Data Models Working Group) where ever possible. At the same time, the data model needs to provide hooks to allow additional metadata to be included in order to describe more specific types of resources.

References and Background

From the Registry Kick-Off Meeting in London, 19-03-2003.

• Tony's notes defining the work packages: TL-IVOARegistry-Day2.ppt
• Elizabeth's presentation on the prototype Astrogrid registry: IVOA_Registry.ppt
• Anita's presentation on Registry Metadata: RegistryMetadata.ppt

See also the Registry WG Session Page for the IVOA Interoperability Workshop held May 12-16, 2003 in Cambridge, England.

Previous Modeling from the NVO:

• Resource Metadata Note: Deprecated by later versions listed in Specifications section below.
  • VOResource
    • based on RSM (V0.6) document by Hanisch et al.
    • Prototype version: VOResource.xsd
    • an example instantiation: adil.xml
    • Comments and illuminating figures

Note that the above Schema is under development and changes often. More stable versions should appear under the Specifications section below.

• Space-Time Metadata
  • Arnold's Space-Time Coordinates page describes the current model and includes a link to a DTD.
  • The current version of the regions schema can be seen as a DTD.

-- RayPlante - 14 Apr 2003

Previous Modeling by the AstroGrid Project:

• some baseline schemas broken down into 6 sets: Registry, Service, workspaceService, dataService, processingService, registryService, serviceLocation.
• some suggested amendments to the baseline proposal.

-- RayPlante - 30 Apr 2003

Notes on Future Revsisions

• VOResource version 0.10 notes

Specifications

This section is for specifications currently under discussion. A spec's inclusion here says nothing about its overall acceptance by the team or community, but rather provides a definitive location for documents under discussion. I recommend that such documents be uploaded (i.e. attached) and labeled with a version number, and all versions should be preserved and accessible. I recommend the following format:

Example:

• Specification for the Specification Section: latest version (1.1)
  Versions: 1.0, 1.1

-- RayPlante - 14 Apr 2003

IVOA Identifiers

• IVOA Identifiers: an IVOA Working Draft. latest version: 0.2 (HTML)
• A compliant XML Schema for the XML format for identifiers: latest version (0.1)
  Versions: 0.2, 0.1
  • Some strawman ideas for amending the Identifier framework for supporting persistance and location-independence.

VOResource: a Resource Metadata Schema

New as of 18 Nov. 2003. Developers have identified a few mistakes in the schemas; as a result, the following files have been updated:

• VOResourceRelType-v0.2.xsd
• VODataServiceCoverage.xsd
• VODataServiceCoverage-v0.2.xsd: this deprecates VODataServiceCoverage-v0.1.xsd.

New as of 5 Nov. 2003. Updated WD versions of the schema are now officially available. Developers should be sure to download the latest versions from the table below (or all of them together: tar-file, zip-file)--even the version number appears unchanged--as the namespace names have all been updated. These are the schemas to be used for January 2004 demos.

The schemas are:

The following two extensions are examples of extensions that define two standard tabular sky services. They include the elements necessary for decribing the tables returned by the services (using VOTable tags). These are included for indicative purposes only.

Example instance containing several resource descriptions:

• adil-v0.9.xml

Download all schemas in one go; two versions are available below. When these packages are unpacked, all files will be put in the current directory.

VOResource-v0.9 (tar.gz, zip)

the official schemas from the table above.

VOResource-v0.9-local (tar.gz, zip)

the official schemas with "schemaLocation" set to look for imports on local disk. This version enables a verifier to look for schemas in the current directory instead from the IVOA site. Use this version when developing off-line or with tools that have trouble finding imported schemas.

More supporting material is coming soon!

See also notes being gathered for Version 0.10

Deprecated Versions

For more detailed information (particularly if you are not used to looking at XML Schema), please see the following additional resources:

VOResource Overview (version 0.8.3)

an overview of the schema containing high-level diagrams, a summary of major changes from the last version, and pointers to more detailed documentation.

adil-v0.8.3.xml

an example instance file describing several resources associated with the NCSA Astronomy Digital Image Library (ADIL), including 3 services for accessing the data.

Schema Documentation

You can interactive browse automatically generated documentation by following the "XMLSpy" or "xs3p" links in the tables above.

-- RayPlante - 22 Apr 2003

Helpful Documentation

Describing Services with VOResource v0.9 -- RayPlante - 17 May 2004

Progress Reports

• 01 Jul 2003: RwpThreeProgressJul2003