This is an IVOA Proposed Recommendation available for public review by all
interested parties. Comments on this document should be made via the IVOA
Request For Comment (RFC) Twiki page,
http://www.ivoa.net/cgi-bin/twiki/bin/view/IVOA/VODataServiceV11RFC
or by via email to registry at ivoa.net. The
deadline comments can be found on the RFC page.
A list of current IVOA
Recommendations and other technical documents can be found at
http://www.ivoa.net/Documents/.
This document has been developed with support from the
National Science Foundation's
Information Technology Research Program under Cooperative Agreement
AST0122449 with The Johns Hopkins University, from the
UK Particle Physics and Astronomy
Research Council (PPARC), and from the
Eurpean Commission's Sixth
Framework Program via the
Optical Infrared Coordination Network (OPTICON).
Conformance-related definitions
The words "MUST", "SHALL", "SHOULD", "MAY", "RECOMMENDED", and
"OPTIONAL" (in upper or lower case) used in this document are to be
interpreted as described in IETF standard, RFC 2119
[RFC 2119].
The Virtual Observatory (VO) is
general term for a collection of federated resources that can be used
to conduct astronomical research, education, and outreach.
The International
Virtual Observatory Alliance (IVOA) is a global
collaboration of separately funded projects to develop standards and
infrastructure that enable VO applications.
XML document validation is a
software process that checks that an XML document is not only
well-formed XML but also conforms to the syntax rules defined by the
applicable schema. Typically, when the schema is defined by one or more
XML Schema [schema] documents (see
next section), validation refers to checking for
conformance to the syntax described in those Schema documents. This
document describes additional syntax constraints that cannot be
enforced solely by the rules of XML Schema; thus, in this document,
use of the term validation includes the extra checks that goes beyond
common Schema-aware parsers which ensure conformance with this
document.
Syntax Notation Using XML Schema
The eXtensible Markup Language, or XML, is document syntax for marking
textual information with named tags and is defined by the
World Wide Web Consortium (W3C) Recommendation,
XML 1.0
[XML]. The set of XML tag names and the syntax
rules for their use is referred to as the document schema. One way to
formally define a schema for XML documents is using the W3C standard
known as XML Schema [schema].
This document defines the VOResource schema using XML Schema. The
full Schema document is listed in Appendix A.
Parts of the schema appear within the main sections of this document;
however, documentation nodes have been left out for the sake of brevity.
Reference to specific elements and types defined in the VOResource
schema include the namespaces prefix, vr, as in
vr:Resource (a type defined in the VOResource schema).
Reference to specific elements and types defined in the VODataService
extension schema include the namespaces prefix, vs, as in
vs:DataCollection (a type defined in the VODataService schema).
Use of the vs prefix in compliant instance documents is
strongly recommended, particularly in the applications that involve
IVOA Registries (see [RI], section 3.1.2). Elsewhere, the use is not
required.
The VOResource standard [VOR] provides a means of
encoding IVOA Resource Metadata [RM] in XML.
VOResource uses XML Schema [schema] to define
most of the XML syntax rules (while a few of the syntax rules are
outside the scope of Schema). VOResource also describes mechanisms
for creating extensions to the core VOResource metadata. This allows
for the standardization of new metadata for describing specialized
kinds of resources in a piecemeal way without deprecating the core
schema or other extensions. This document defines one such extension
referred to as VODataService.
The purpose of this extension is to define common XML Schema
types--particularly new resource types--that are useful for describing
data collections and services that access data. In particular, it
allows one to describe the data's coverage: the parts of the
sky with which the data are associated and the time and frequency ranges that
were observed or modeled to create the data. It also allows one to
describe tables in detail. In particular, one can describe each of
the columns of a table--providing, for example, its name, type, UCD
[UCD],
and textual description. When this metadata is part of a resource
description in a registry [VOR], it becomes possible
to discover tables that contains particular kinds of data.
It is intended that VODataService will be central to describing
services that support standard IVOA data access layer protocols such
as Simple Image Access [SIA] and Simple Cone Search
[SCS]. While other VOResource extensions would
define the protocol-specific metadata (encapsulated as a standard
capability [VOR]), the general service
resource description would share the common data concepts such as
coverage and tabular data. Note, however, that a service described
using the VODataService schema need not support any standard
protocols. With the VODataService extension schema plus the core
VOResource schema, it is possible to describe a custom service
interface that accesses data.
As a legal extension of VOResource [VOR], the use
of VODataService is subject to the rules and recommendations for XML
[xml], XML Schema [schema],
and VOResource itself.
2. The VODataService Data Model
The VODataService extension in general enables the description of two
types of resources: data collections and services that access data.
Here's an example of a VOResource document (abbreviated for the
purposes of illustration) that describes a service from the NASA
Extragalactic Database (NED) that provides measured redshifts for a
given object.
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<?xml version="1.0" encoding="UTF-8"?>
<ri:Resource xmlns=""
xsi:type="vs:CatalogService" status="active"
updated="2008-04-29T14:51:54" created="2005-10-14T01:46:00"
xmlns:ri="http://www.ivoa.net/xml/RegistryInterface/v1.0"
xmlns:vr="http://www.ivoa.net/xml/VOResource/v1.0"
xmlns:vs="http://www.ivoa.net/xml/VODataService/v1.1"
xmlns:stc="http://www.ivoa.net/xml/STC/stc-v1.30.xsd"
xmlns:xlink="http://www.w3.org/1999/xlink"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.ivoa.net/xml/VOResource/v1.0
http://www.ivoa.net/xml/VOResource/v1.0
http://www.ivoa.net/xml/VODataService/v1.1
http://www.ivoa.net/xml/VODataService/v1.1
http://www.ivoa.net/xml/STC/stc-v1.30.xsd
http://www.ivoa.net/xml/STC/stc-v1.30.xsd">
<title>The NASA/IPAC Extragalactic Database</title>
<shortName>NED_redshift</shortName>
<identifier>ivo://ned.ipac/Redshift_By_Object_Name</identifier>
<curation>
<publisher>The NASA/IPAC Extragalactic Database</publisher>
<contact>
<name>Olga Pevunova</name>
<email>contact@datacenter.edu</email>
</contact>
</curation>
<content>
<subject>redshift</subject>
<subject>galaxies</subject>
<description>
NED is built around a master list of extragalactic objects for
which cross-identifications of names have been established,
accurate positions and redshifts entered to the extent possible,
and some basic data collected. This service will return recorded
redshifts for a given object.
</description>
<referenceURL>http://nedwww.ipac.caltech.edu/help/data_help.html#zdat</referenceURL>
<type>BasicData</type>
<contentLevel>Research</contentLevel>
</content>
<capability>
<interface xsi:type="vs:ParamHTTP">
<accessURL use="base">
http://nedwww.ipac.caltech.edu/cgi-bin/nph-datasearch?search_type=Redshifts&
</accessURL>
<queryType>GET</queryType>
<resultType>application/xml+votable</resultType>
<param use="required">
<name>objname</name>
<description>Name of object</description>
<dataType>string</dataType>
</param>
<param use="required">
<name>of</name>
<description>Output format parameter, must be "xml_main" for VOTable output.</description>
<dataType>string</dataType>
</param>
</interface>
</capability>
<coverage>
<stc:STCResourceProfile>
<stc:AstroCoordSystem xlink:type="simple"
xlink:href="ivo://STClib/CoordSys#UTC-FK5-TOPO"
id="UTC-FK5-TOPO"/>
<stc:AstroCoordArea coord_system_id="UTC-FK5-TOPO">
<stc:AllSky/>
</stc:AstroCoordArea>
</stc:STCResourceProfile>
<waveband>Radio</waveband>
<waveband>Optical</waveband>
</coverage>
<tableset>
<schema>
<name>default</name>
<table type="output">
<name>default</name>
<column>
<name>No.</name>
<description>
A sequential data-point number applicable to this list only.
</description>
<ucd>meta.number</ucd>
<dataType xsi:type="vs:VOTableType">int</dataType>
</column>
<column>
<name>Name in Publication</name>
<description>
The object's name in NED's standard format, of the object to which the data apply.
</description>
<ucd>meta.id;name</ucd>
<dataType xsi:type="vs:VOTableType">string</dataType>
</column>
<column>
<name>Published Velocity</name>
<description>
The radial velocity , derived from derived from the shift of some spectral feature, in km/sec
</description>
<unit>km/sec</unit>
<ucd>src.spect.dopplerVeloc</ucd>
<dataType xsi:type="vs:VOTableType">int</dataType>
</column>
</table>
</schema>
</tableset>
</ri:Resource>
|
This example illustrates some of the features of the VODataService
extension:
- the extra namespaces associated with
VODataService metadata; if STC coverage information
[STC] is not
included, then only the VODataService namespaced is needed.
- the specific type of resource indicated by
the value of the
xsi:type attribute; in this case
vs:CatalogService indicates that this is
describing a service that accesses tabular data.
- the location of the VOResource-related schema
documents used by this description,
- the core VOResource metadata,
- an interface described by the
VODataService interface type,
vs:ParamHTTP; this
type can indicate input arguments it supports.
- a description of the
coverage, including an STC
description plus waveband keywords.
- a description of the table that is returned
by the service.
The namespace associated with VODataService extensions is
"http://www.ivoa.net/xml/VODataService/v1.1".
Just like the namespace URI for the VOResource schema, the
VODataService namespace URI can be interpreted as a URL. Resolving it
will return the XML Schema document (given in Appendix A)
that defines the VODataService schema.
Authors of VOResource instance documents may choose to
provide a location for the VOResource XML Schema document and its
extensions using the
xsi:schemaLocation attribute. While the choice of
the location value is the choice of the author, this specification
recommends using the VODataService namespace URI as its location URL
(as illustrated in the example above), as in,
xsi:schemaLocation="http://www.ivoa.net/xml/VODataService/v1.1
http://www.ivoa.net/xml/VODataService/v1.1"
- Note:
- The IVOA Registry Interface standard [RI]
actually requires that the VOResource records it
shares with other registries provide location URLs via
xsi:schemaLocation for the VOResource schema and
all legal extension schemas that are used in the records. This
rule would apply to the VODataService schema.
|
The prefix, vs, is used by convention as the prefix
defined for the VODataService schema; however, instance documents may
use any prefix. In applications where common use of prefixes is
recommended (such as with the Registry Interface specification [RI]), use of the vs prefix is recommended.
Note also that in this document, the vr prefix is used to
label, as shorthand, a type or element name that is defined in the
VOResource schema, as in vr:Resource.
- Note:
- One reason one may not be able to use
vs
to represent the VODataService schema, version 1.1, is because
it is already in defined to represent VODataService v1.0 and
cannot be overridden. At this writing, there are no IVOA
applications in which this is the case. Consult
Appendix B for more details on
compatibility issues.
|
As recommend by the VOResource standard [VOR], the
VODataService schema sets elementFormDefault="unqualified".
This means that it is not necessary to qualify element names defined
in this schema with a namespace prefix (as there are no global
elements defined). The only place it is usually needed is as a
qualifier to a VODataService type name given as the value of an
xsi:type attribute.
2.2. Summary of Metadata Concepts
The VODataService extension defines four new types of resources. Two inherit
directly from vr:Resource:
-
vs:DataCollection
- This resource declares the existence of a collection of data, what
it represents, and how to get it. The access to the data may be
limited to a human-readable web page (given by
content/referenceURL); however, if the
contents of the collection are available statically via a
URL (e.g. an FTP URL to a directory containing all the files),
that URL can be provided. It can also provide pointers to
other IVOA registered services that can be used to access the data.
-
vs:StandardSTC
- This resource type declares one or more coordinate systems described
using STC [STC] such that each can be
assigned a globally unique identifier (based on the IVOA
identifier for the resource record itself). This identifier
can then be referenced in any other STC description in lieu of
a fully described coordinate system. Coordinate system
described in this way become reusable standards once they are
registered in an IVOA registry.
The other two resource types represent specialized services:
-
vs:DataService
- Inheriting from
vr:Service, this type is for
services that access astronomical data. It adds the ability to
describe the data's coverage of the
sky, frequency, and time.
-
vs:CatalogService
- Inheriting from
vs:DataService, this type
specifically refers to a service that accesses tabular data.
In addition to the coverage information, this type adds the
ability to describe the tables and their columns. This is
intended for describing services that support the "simple" IVOA
data access layer protocols such as Simple Image Access
[SIA] and Simple Cone Search
[SCS].
In general, coverage refers to
the extent that data samples the measurement range of the sky (space),
frequency, and time. The coverage metadata (encoded via the
vs:Coverage type) has two parts. The first part
allows a full STC profile description (via the imported STC element,
<stc:STCResourceProfile>). The second part
captures key coverage metadata defined in the IVOA Resource Metadata
standard [RM]. The RM-derived coverage elements can
be considered summarizing metadata for many of the details that
may appear within the STC description, and enables simpler
searching of high-level coverage information.
The detailed STC profile contained within the
<stc:STCResourceProfile> element is capable of
describing coverage not only in space, time, and frequency but also
velocity and redshift. The profile contains up to three types of
component descriptions ([STC], section 4.1):
coordinate systems, coordinate values, and coordinate areas or ranges.
The first component describes the coordinate systems to which coordinate
values, areas, and regions are referenced. While any arbitrary
system can be described in this first part, it is expected that most
VODataService instances will provide a simple pointer to a predefined
system in a registered vs:StandardSTC record (using the
mechanism summarized in section 3.1.2 below). The coordinate values
part will usually be used to describe the coordinate resolution,
errors, or typical sizes. The coordinate areas part describes actual
regions or ranges covered by the resource in any of the given
coordinate systems.
Table descriptions appear within a single <tableset>
element. This element can in turn can contain one or more
<schema> element in which each schema
represents a set of logically related tables. It is not required that
that the schema grouping match the underlying database's
catalogs or schemas (as defined in
[SQLGuide]), though it may. In some cases,
such as when describing the table that is returned from an SIA
service, the terms catalog and schema may have
little relevance; in this case, the table can be considered part of a
sole "default" schema.
For each table in a schema, one can describe each of the columns,
providing such information as its name, type, UCD [UCD],
units, and a textual description. Providing this information makes it
possible to select a resource based on the kind data contained in its
tables.
Finally, the VODataService defines specialized interface type
(inheriting from vr:Interface) called
vs:ParamHTTP. This type is used to describe the commonly
used interface that is invoked over HTTP as either a GET or a POST
[HTTP] in which the arguments are encoded as
name=value pairs. In addition to the access URL, it can
include not only the mime-type of the returned response, it can also
enumerate the input arguments that are supported by the service
implementation. Much like table columns, one can indicate for each
argument the name, the UCD, the data type, the units, whether it is
required, and a textual description the argument. Note that this does
not capture any interdependencies between arguments. For example, it
cannot indicate if one argument only makes sense in the presence of
another argument.
3. The VODataService Metadata
This section enumerates the types and elements defined in the
VODataService extension schema and describes their meaning. Where a
term matches a term in the RM, its meaning is given
in terms of the RM definition.
3.1. Resource Type Extensions
3.1.1. DataCollection
A data collection, which is describable with the
vs:DataCollection resource type, is a logical
group of data composed of one or more accessible
datasets. A collection can contain any combination of images,
spectra, catalogs, time-series, or other data. (In contrast, we talk
about a dataset as being a set of digitally-encoded
data that is normally accessible as a single unit--e.g., a file.)
The vs:DataCollection type adds seven additional metadata
elements beyond the core VOResource metadata [VOR].
<xs:complexType name="DataCollection">
<xs:complexContent>
<xs:extension base="vr:Resource">
<xs:sequence>
<xs:element name="facility" type="vr:ResourceName"
minOccurs="0" maxOccurs="unbounded"/>
<xs:element name="instrument" type="vr:ResourceName"
minOccurs="0" maxOccurs="unbounded"/>
<xs:element name="rights" type="vr:Rights"
minOccurs="0" maxOccurs="unbounded"/>
<xs:element name="format" type="vs:Format"
minOccurs="0" maxOccurs="unbounded"/>
<xs:element name="coverage" type="vs:Coverage" minOccurs="0"/>
<xs:element name="tableset" type="vs:TableSet" minOccurs="0">
<xs:unique name="DataCollection-schemaName">
<xs:selector xpath="schema" />
<xs:field xpath="name" />
</xs:unique>
<xs:unique name="DataCollection-tableName">
<xs:selector xpath="schema/table" />
<xs:field xpath="name" />
</xs:unique>
<xs:element>
<xs:element name="accessURL" type="vr:AccessURL" minOccurs="0"/>
</xs:sequence>
</xs:extension>
</xs:complexContent>
</xs:complexType>
The definition of <tableset> element places forces certain
names within its description to be unique; these constraints are explained
further in 3.3.1.
All of the child elements except <tableset> derive
from RM terms. Four of the elements--<facility>,
<instrument>, <rights>,
and <accessURL>--are reuses of elements defined in
the core VOResource schema, sharing the same syntax and similar
semantics. In particular, the meanings of <facility>
and <instrument> in the context of
vs:DataCollection are different from that in
vr:Organisation only in that in the former type, they refer
to the origin of the data.
| vs:DataCollection Extension Metadata Elements |
|---|
| Element | Definition |
|---|
| facility |
| RM Name: |
Facility |
| Value type: |
string with optional ID attribute: vr:ResourceName |
| Semantic Meaning: |
the observatory or facility
used to collect the data contained or managed by
this resource. |
| Occurrences: |
optional; multiple occurrences allowed |
|
| instrument |
| RM Name: |
Instrument |
| Value type: |
string with optional ID attribute: vr:ResourceName |
| Semantic Meaning: |
the instrument used to
collect the data contained or managed by this resource. |
| Occurrences: |
optional; multiple occurrences allowed |
|
| rights |
| RM Name: |
Rights |
| Value type: |
string, controlled vocabulary:
xs:token |
| Semantic Meaning: |
Information about rights
held in and over the resource. |
| Occurrences: |
optional; multiple occurrences allowed |
| Allowed Values: |
public |
unrestricted, public access is
allowed without authentication. |
secure |
authenticated, public access is allowed. |
proprietary |
only proprietary access is allowed with
authentication. |
|
|
| format |
| RM Name: |
Format |
| Value type: |
string with optional
isMIMEType attribute, vs:Format |
| Semantic Meaning: |
The physical or digital
manifestation of the information supported by a resource. |
| Occurrences: |
optional; multiple occurrences allowed |
| Comments: |
MIME types should be used for
network-retrievable, digital data, and the
isMIMEType attribute should be set
to explicitly to "true". Non-MIME
type values are used for media that cannot be
retrieved over the network--e.g. CDROM, poster,
slides, video cassette, etc. |
|
| coverage |
| RM Name: |
Coverage |
| Value type: |
composite; vs:Coverage |
| Semantic Meaning: |
Extent of the content of
the resource over space, time, and frequency. |
| Occurrences: |
optional |
|
| tableset |
| Value type: |
composite; vs:TableSet |
| Semantic Meaning: |
A description of tables
that are part of this collection. |
| Occurrences: |
optional. |
|
| accessURL |
| RM Name: |
Service.AccessURL |
| Value type: |
URL with optional use attribute: vr:AccessURL |
| Semantic Meaning: |
The URL can be used to
download the data contained in this data collection. |
| Occurrences: |
required; multiple occurrences allowed. |
|
The vs:Format type is used for
providing a value to the <format> element:
<xs:complexType name="Format">
<xs:simpleContent>
<xs:extension base="xs:token">
<xs:attribute name="isMIMEType" type="xs:boolean" default="false"/>
</xs:extension>
</xs:simpleContent>
</xs:complexType>
The isMIMEType attribute
provides a flag to indicate if the value represents an actual
MIME-type: if it is, this attribute should be explicitly set to
"true".
See section 3.3 for a specification of
the vs:TableSet type for describing tables.
3.1.2. StandardSTC
The vs:StandardSTC resource type is used to register standard
coordinate systems, positions, or regions using the Space-Time
Coordinate (STC, [STC]) standard schema so that
they can by uniquely referenced by name by other resource descriptions
or applications. This resource type extends the core metadata with a
single element, <stcDefinitions>, which contains
the STC definitions.
<xs:complexType name="StandardSTC">
<xs:complexContent>
<xs:extension base="vr:Resource">
<xs:sequence>
<xs:element name="stcDefinitions"
type="stc:STCResourceProfile"
minOccurs="0" maxOccurs="unbounded"/>
</xs:sequence>
</xs:extension>
</xs:complexContent>
</xs:complexType>
The curation metadata that is part of the core VODataService should
generally refer to the publishing organization and persons that are
responsible for defining the systems, updating the definitions as
needed, and responding to user questions about the definitions. The
content metadata, in particular the textual contents of the
<description> element, should describe the purpose
of the definition and where references to the defined systems,
positions, or regions may be used.
| vs:StandardSTC Extension Metadata Elements |
|---|
| Element | Definition |
|---|
| stcDefintions |
| Value type: |
composite;
stc:stcDescriptionType |
| Semantic Meaning: |
the definitions of systems,
positions, and regions that are available for referencing. |
| Occurrences: |
required; multiple occurrences allowed |
|
The content of the <stcDefinitions> element is
controlled by the STC schema. Because that schema uses the
elementFormDefault="true" and most of the STC elements
are defined to be global [schema],
<stcDefinitions> child elements must be qualified
as being in the STC namespace
(http://www.ivoa.net/xml/STC/stc-v1.30.xsd), by either setting the
default namespace (via the xmlns attribute) or via
explicit qualification via a prefix (see example).
3.1.3. DataService
The vs:DataService resource type is for describing a
service that provides access to astronomical data. This service adds
to the core VOResource service metadata the ability to associate an
observing facility and/or instrument with the data as well as describe
the coordinate coverage of data via its child <coverage>
element. Note that while these elements are all optional, a resource
of this type still implies access to astronomical data.
<xs:complexType name="DataService">
<xs:complexContent>
<xs:extension base="vr:Service">
<xs:sequence>
<xs:element name="facility" type="vr:ResourceName"
minOccurs="0" maxOccurs="unbounded"/>
<xs:element name="instrument" type="vr:ResourceName"
minOccurs="0" maxOccurs="unbounded"/>
<xs:element name="coverage" type="vs:Coverage" minOccurs="0"/>
</xs:sequence>
</xs:extension>
</xs:complexContent>
</xs:complexType>
The use and meaning of the <facility> and
<instrument> elements are the same as for
vs:DataCollection.
| vs:DataService Extension Metadata Elements |
|---|
| Element | Definition |
|---|
| facility |
| RM Name: |
Facility |
| Value type: |
string with optional ID attribute: vr:ResourceName |
| Semantic Meaning: |
the observatory or facility
used to collect the data contained or managed by
this resource. |
| Occurrences: |
optional; multiple occurrences allowed |
|
| instrument |
| RM Name: |
Instrument |
| Value type: |
string with optional ID attribute: vr:ResourceName |
| Semantic Meaning: |
the instrument used to
collect the data contained or managed by this resource. |
| Occurrences: |
optional; multiple occurrences allowed |
|
| coverage |
| RM Name: |
Coverage |
| Value type: |
composite; vs:Coverage |
| Semantic Meaning: |
Extent of the content of the resource over space, time, and frequency. |
| Occurrences: |
optional |
|
The contents of the <coverage> element are detailed
in section 3.2.
3.1.4. CatalogService
The vs:CatalogService resource type is for describing a
service that interacts with astronomical data through one or more
specified tables. Because it extends the vs:DataService
type, a catalog service can have a coverage description as well. The
tabular data may optionally be described via a
<tableset> element.
<xs:complexType name="CatalogService">
<xs:complexContent>
<xs:extension base="vs:DataService">
<xs:sequence>
<xs:element name="tableset" type="vs:TableSet" minOccurs="0">
<xs:unique name="CatalogService-schemaName">
<xs:selector xpath="schema" />
<xs:field xpath="name" />
</xs:unique>
<xs:unique name="CatalogService-tableName">
<xs:selector xpath="schema/table" />
<xs:field xpath="name" />
</xs:unique>
<xs:element>
</xs:sequence>
</xs:extension>
</xs:complexContent>
</xs:complexType>
The definition of <tableset> element forces certain
names within its description to be unique; these constraints are explained
further in 3.3.1.
| vs:CatalogService Extension Metadata Elements |
|---|
| Element | Definition |
|---|
| tableset |
| Value type: |
composite; vs:TableSet |
| Semantic Meaning: |
A description of the tables that are accessible
through this service. |
| Occurrences: |
optional |
|
3.2. Coverage
The vs:Coverage type describes how the data samples the
sky, frequency, and time.
<xs:complexType name="Coverage">
<xs:sequence>
<xs:element ref="stc:STCResourceProfile" minOccurs="0"/>
<xs:element name="footprint" type="vs:ServiceReference"
minOccurs="0"/>
<xs:element name="waveband" type="vs:Waveband"
minOccurs="0" maxOccurs="unbounded"/>
<xs:element name="regionOfRegard" type="xs:float"
minOccurs="0" maxOccurs="unbounded"/>
</xs:sequence>
</xs:complexType>
A detailed, systematic description of coverage is provided via the
child <stc:STCResourceProfile> element, taken from
the STC schema, version 1.3, with the namespace,
http://www.ivoa.net/xml/STC/stc-v1.30.xsd (hereafter
referred using the stc: prefix). This element is defined
in the STC schema as a global element; furthermore, the STC schema
sets its global elementFormDefault="qualified".
Consequently, the <stc:STCResourceProfile> element
and all its child elements must be qualified as part of the STC
namespace as required by XML Schema [schema].
In applications where common use of XML prefixes is required or
encouraged (e.g. the IVOA Registry Interfaces [RI]),
use of the stc: prefix to represent the STC namespace is
encouraged.
The remaining elements provide some summary information about the
coverage.
| vs:Coverage Metadata Elements |
|---|
| Element | Definition |
|---|
| STCResourceProfile |
| Value type: |
composite: an
stc:STCResourceProfile element from the
STC schema. |
| Semantic Meaning: |
The STC description of the location of the resource's
data (or behavior on data) on the sky, in time, and in
frequency space, including resolution. |
| Occurrences: |
optional |
| Comments: |
In general, this description should be
approximate; a more precise description can be provided
by the service referred to by the
<footprint> element. |
|
| footprint |
| Value type: |
a URL with an optional IVOA identifier attribute: |
| Semantic Meaning: |
a reference to a footprint service for retrieving
precise and up-to-date description of coverage. |
| Occurrences: |
optional |
| Comments: |
the ivo-id attribute
refers to a Service record having a footprint
service capability. That is, the record will have a
capability element describing the footprint service
(see "Note on Footprint
Service" below for further discussion).
The resource referred to may be the current one. |
|
| waveband |
| RM Name: |
Coverage.Spectral |
| Value type: |
string with controlled vocabulary: vs:Waveband |
| Semantic Meaning: |
a named spectral region of
the electro-magnetic spectrum that the resource's
spectral coverage overlaps with. |
| Occurrences: |
optional; multiple occurrences allowed |
| Allowed Values: |
Radio |
any wavelength > 10 mm (or frequency < 30 GHz)
|
Millimeter |
0.1 mm <= wavelength <= 10 mm;
3000 GHz >= frequency >= 30 GHz.
|
Infrared |
1 micron <= wavelength <= 100 microns
|
Optical |
0.3 microns <= wavelength <= 1 micron;
300 nm <= wavelength <= 1000 nm;
3000 Angstroms <= wavelength <= 10000 Angstroms
|
UV |
0.1 micron <= wavelength <= 0.3 microns;
100 nm <= wavelength <= 3000 nm;
1000 Angstroms <= wavelength <= 30000 Angstroms
|
EUV |
100 Angstroms <= wavelength <= 1000 Angstroms;
12 eV <= energy <= 120 eV
|
X-ray |
0.1 Angstroms <= wavelength <= 100 Angstroms;
0.12 keV <= energy <= 120 keV
|
Gamma-ray |
energy >= 120 keV
|
|
|
| regionOfRegard |
| RM Name: |
Coverage.RegionOfRegard |
| Value type: |
a floating point number: xs:float |
| Semantic Meaning: |
a single numeric value representing the angle, given
in decimal degrees, by which a positional query
against this resource should be "blurred" in order
to get an appropriate match. |
| Occurrences: |
optional |
| Comments: |
In the case of image repositories, this value might
refer to a typical field-of-view size, or the
primary beam size for radio aperture synthesis data.
In the case of object catalogs, region of regard
should normally be the largest of the typical size
of the objects, the astrometric errors in the
positions, or the resolution of the data. |
|
- Note on Footprint Service:
- The
<footprint> element has been defined in
anticipation of a future standard IVOA footprint service
protocol that can be used to respond to detailed spatial
overlap queries. Consequently, in the future, applications may
be able to assume the protocol that footprint service URL
supports. When an application is unable to make any
assumptions, the IVOA Identifier given by the attribute should
be resolved and the returned resource description should be
searched for a recognized footprint service capability.
|
3.3. Tabular Data
The vs:TableSet type can be used
to describe a set of tables that are part of a single resource and can
be consider functionally all located at a single site.
<xs:complexType name="TableSet">
<xs:sequence>
<xs:element name="schema" type="vs:TableSchema"
minOccurs="1" maxOccurs="unbounded"/>
</xs:sequence>
<xs:anyAttribute namespace="##other" />
</xs:complexType>
| vs:TableSet Metadata Elements |
|---|
| Element | Definition |
|---|
| schema |
| Value type: |
composite; vs:TableSchema |
| Semantic Meaning: |
A named description of a set of logically related tables. |
| Occurrences: |
required; multiple occurrences are allowed. |
| Comments: |
See section 3.3.1
regarding unique names for schemas. |
|
The vs:TableSchema type collects
tables together that are logically related. For example, a single
resource may provide access several major astronomical catalogs
(e.g. SDSS, 2MASS, and FIRST) from one site, enabling high-performance
cross-correlations between them. Each catalog can be described in a
separate <schema> element, using the elements from
the vs:TableSchema type.
<xs:complexType name="TableSchema">
<xs:sequence>
<xs:element name="name" type="xs:token" minOccurs="1" maxOccurs="1"/>
<xs:element name="title" type="xs:token" minOccurs="0"/>
<xs:element name="description" type="xs:token"
minOccurs="0" maxOccurs="1"/>
<xs:element name="utype" type="xs:token" minOccurs="0"/>
<xs:element name="table" type="vs:Table"
minOccurs="0" maxOccurs="unbounded"/>
</xs:sequence>
<xs:anyAttribute namespace="##other" />
</xs:complexType>
| vs:TableSchema Metadata Elements |
|---|
| Element | Definition |
|---|
| name |
| Value type: |
string: xs:token |
| Semantic Meaning: |
A name for the set of tables. |
| Occurrences: |
required |
| Comments: |
If there is no appropriate logical name associated with
this set, the name should be explicitly set to
"default". See section 3.3.1
regarding the uniqueness of this name. |
|
| title |
| Value type: |
string: xs:token |
| Semantic Meaning: |
a descriptive, human-interpretable name for the table set. |
| Occurrences: |
optional |
| Comments: |
This is used for display purposes and is useful when there are
multiple schemas in the context (e.g. within a
tableset; otherwise, the resource title could be
used instead). Note, however, that there is no requirement
regarding uniqueness. If a title is not provided,
the schema name can be used for display purposes. |
|
| description |
| Value type: |
string: xs:token |
| Semantic Meaning: |
A free text description of
the tableset that should explain in general how all
of the tables are related. |
| Occurrences: |
optional |
|
| utype |
| Value type: |
string: xs:token |
| Semantic Meaning: |
an identifier for a concept in a data model that
the data in this schema as a whole represent. |
| Occurrences: |
optional |
| Comments: |
The format defined in the VOTable standard, section 4.1
[VOTable] is strongly
recommended; see "Note on UType
Format below. |
|
| table |
| Value type: |
composite: vs:Table |
| Semantic Meaning: |
A marked description of one of the tables that makes up the set. |
| Occurrences: |
optional; multiple occurrences are allowed. |
| Comments: |
See section 3.3.1
regarding unique names for schemas. |
|
- Note on UType Format:
- As of this writing, an IVOA standard for the format of utypes
is still under development. As a result, the most definitive
documentation of the format is in section 4.1 of the VOTable
specification [VOTable], which is
expected to be a more general form to be spelled out in the
eventual utype standard. Use of that latter standard is
recommended once it becomes available.
|
Each table in a schema is described in detail using the
vs:Table type.
<xs:complexType name="Table">
<xs:sequence>
<xs:element name="name" type="xs:token"
minOccurs="1" maxOccurs="1"/>
<xs:element name="title" type="xs:token" minOccurs="0"/>
<xs:element name="description" type="xs:token" minOccurs="0"/>
<xs:element name="utype" type="xs:token" minOccurs="0"/>
<xs:element name="column" type="vs:TableParam"
minOccurs="0" maxOccurs="unbounded"/>
</xs:sequence>
<xs:attribute name="type" type="xs:string"/>
<xs:anyAttribute namespace="##other" />
</xs:complexType>
| vs:Table Metadata Elements |
|---|
| Element | Definition |
|---|
| name |
| Value type: |
string: xs:token |
| Semantic Meaning: |
A fully qualified name for
the table. This name should include all catalog or schema
prefixes needed to sufficiently uniquely distinguish it in a
query to the table. |
| Occurrences: |
required |
| Comments: |
In general, the format of the qualified name may
depend on the on the context; however, when the
table is intended to be queryable via ADQL
[ADQL], then the
catalog and schema qualifiers are delimited from the
table name with dots (.).
If this table is part of the schema named "default",
the schema name does not need to appear in this table
name, unless it is required by an associated access
service.
If there is no appropriate logical name associated with
this table, the name should be explicitly set to
"default". See section 3.3.1
regarding the uniqueness of this name. |
|
| title |
| Value type: |
string: xs:token |
| Semantic Meaning: |
a descriptive, human-interpretable name for the table set. |
| Occurrences: |
optional |
| Comments: |
This is used for display purposes. There is no requirement
regarding uniqueness. If a title is not provided,
the table name can be used for display purposes. |
|
| description |
| Value type: |
string: xs:token |
| Semantic Meaning: |
A free-text description of
the table's contents. |
| Occurrences: |
optional |
|
| utype |
| Value type: |
string: xs:token |
| Semantic Meaning: |
an identifier for a concept in a data model that
the data in this table as a whole represent. |
| Occurrences: |
optional |
| Comments: |
The format defined in the VOTable standard, section 4.1
[VOTable] is strongly
recommended; see "Note on UType
Format above. |
|
| column |
| Value type: |
composite: vs:TableParam |
| Semantic Meaning: |
A marked description of one of the table's columns. |
| Occurrences: |
optional; multiple occurrences are allowed. |
| Comments: |
See section 3.5 for the
description of this element's contents. |
|
| foreignKey |
| Value type: |
composite: vs:ForeignKey |
| Semantic Meaning: |
A description of a foreign
keys, one or more columns from the current table that
can be used to join with another table. |
| Occurrences: |
optional; multiple occurrences are allowed. |
| Comments: |
See section 3.5.2 for the
description of this element's contents. |
|
Each column in a table can be described using the
vs:TableParam type which is described in
section 3.5. The foreign keys in the table that
can be used to join it with another table can be described with the
vs:ForeignKey type (section 3.3.2).
A foreign key description should only refer to tables described within
the current table set.
The vs:Table also provides an attribute for indicating
the role a table plays in the schema:
| vs:Table Attributes |
|---|
| Attribute | Definition |
|---|
type |
| Value type: |
string: xs:token |
| Semantic Meaning: |
a name indicating the role this table plays.
|
| Occurrences: |
optional |
| Recommeded Values: |
output | |
this table structure is used to format the
output from a query
|
base_table | |
this table contains records that represent the
main subjects of the parent schema; other
tables contain ancillary data.
|
view | |
the table represents a useful combination or
subset of other tables. |
Other values are allowed.
|
|
3.3.1. Unique Names for Tables
The definitions of the <tableset> elements used in
the vs:DataCollection and
vs:CatalogService types
constrain certain names to be unique. In particular, all schema names
within a <tableset> element must be unique, and all
table names within a <tableset> element must be
unique. (A schema and table may share a common name, such as
"default".) These constraints makes it possible to uniquely locate
the description of a schema or table within a VOResource description.
The uniqueness constraints for names
within table sets guarantee that when the following XPath queries are
applied to a <tableset> element, zero or one node
only will be returned:
schema[@name="default"]
schema/table[@name="default"]
Name uniqueness is only required when the table set description is
part of a VOResource description. The name uniqueness rules
should also be applied to other uses of the
vs:TableSet element outside of a VOResource
description.
3.3.2. Foreign Keys
The vs:ForeignKey type allows one to describe foreign
keys in a table that allow it to be joined effectively with another
table. A foreign key is a set of columns that map to a corresponding
set of columns in another table.
<xs:complexType name="ForeignKey">
<xs:sequence>
<xs:element name="targetTable" type="xs:token"/>
<xs:element name="fkColumn" type="vs:FKColumn"
minOccurs="1" maxOccurs="unbounded"/>
<xs:element name="description" type="xs:token" minOccurs="0"/>
<xs:element name="utype" type="xs:token" minOccurs="0"/>
</xs:sequence>
</xs:complexType>
In this model, the source of the foreign
key is the current table being described (i.e. represented by the
<table> element that contains the
vs:ForeignKey description, and thus doesn't need to be
named explicitly). The key that is described points to the table
given by the <targetTable> child element. Each child
<fkColumn> element then gives a pair of columns, one
from the source table and one from the target table, that can be
constrained to be equal in a query that joins the two tables.
| vs:ForeignKey Metadata Elements |
|---|
| Element | Definition |
|---|
| targetTable |
| Value type: |
string: xs:token |
| Semantic Meaning: |
the fully-qualified name
(including catalog and schema, as
applicable) of the table that can be joined with the
table containing this foreign key. |
| Occurrences: |
required |
|
| fkColumn |
| Value type: |
composite:
vs:FKColumn |
| Semantic Meaning: |
a pair of column names, one
from this table and one
from the target table that should be used to join the
tables in a query. |
| Occurrences: |
required; multiple occurrences are allowed. |
| Comments: |
There should be one
<fkColumn> element for each column
that makes up the foreign key. |
|
| description |
| Value type: |
string: xs:token |
| Semantic Meaning: |
a free-text description of what this key points to
and what the relationship means |
| Occurrences: |
optional |
|
| utype |
| Value type: |
string: xs:token |
| Semantic Meaning: |
an identifier for a concept
in a data model that the association enabled by this
key represents. |
| Occurrences: |
optional |
| Comments: |
The format defined in the VOTable standard, section 4.1
[VOTable] is strongly
recommended; see "Note on UType
Format" above. |
|
<xs:complexType name="FKColumn">
<xs:sequence>
<xs:element name="fromColumn" type="xs:token"/>
<xs:element name="targetColumn" type="xs:token"/>
</xs:sequence>
</xs:complexType>
| vs:FKColumn Metadata Elements |
|---|
| Element | Definition |
|---|
| fromColumn |
| Value type: |
string: xs:token |
| Semantic Meaning: |
The unqualified name of the column from the current table. |
| Occurrences: |
required |
|
| targetColumn |
| Value type: |
string: xs:token |
| Semantic Meaning: |
The unqualified name of the column from the target table. |
| Occurrences: |
required |
|
a description of a foreign key in an
observation table pointing into a filter table.
<tableset>
<schema>
<name> LSST </name>
<table>
<name> LSST.Filters </name>
<description> a description of the filters used in observations </description>
<column>
<name>ID</name>
...
</column>
...
</table>
<table>
<name> LSST.Observations </name>
<description> a listing of the observations made </description>
<column>
<name>filterID</name>
<description>
the key into the Filter table pointing to the filter used
in the observation.
</description>
...
</column>
...
<foreignKey>
<targetTable> LSST.Filters </targetTable>
<fkColumn>
<fromColumn> filterID </fromColumn>
<targetColumn> ID </targetColumn>
</fkColumn>
</foreignKey>
</table>
</schema>
</tableset>
3.3.3. Extending Table Metadata
It is envisioned that it may be useful in the future to provide richer
metadata for describing tables within a VOResource description than
what are defined in this document. This document recommends the
use of the following extension mechanisms when richer descriptions are
desired:
- Use extended types by applying the
xsi:type
attribute to the <tableset>,
<schema>, <table>,
<column> and/or
<dataType> elements. The values provided in the
attributes must refer to an XML type legally extended from the types
associated with these elements according to the rules of XML Schema
[schema] and the VOResource specification
[VOR].
- Apply a globally-defined attribute from a schema other than
VODataService (i.e. from a namespace other than
"http://www.ivoa.net/xml/VODataService/v1.1") to any of the
<tableset>, <schema>,
<table>, and/or <column>
elements.
- When the extended metadata is specific to how the table data is
accessed via a particular service protocol, then the new
metadata can be incorporated into a specific capability
extension (as described in the VOResource specification
[VOR]). This extension may make use of the
various names within the
<tableset> to
indicate where the extension metadata apply.
- Use the
extendedType attribute of the
<dataType> element (see
section 3.5.3)
to indicate a more specific data type then those defined by the
vs:TableParam type.
3.4. Interface Type Extension: ParamHTTP
The vs:ParamHTTP type is a specialized service interface
description that extends the VOResource vr:Interface type
(as recommended by [VOR], section 2.3.2). It
describes a service interface that is invoke over HTTP via a GET or a
POST [HTTP] in which the inputs are parameters
encoded as name=value pairs, delimited by ampersands
(&) and URL-encoded [URI]. When
the service is invoked as a GET service, this input list is appended
to a base URL (where the result must form a legal URL. Usually, the
URL contains a question mark (?) setting off a list of
URL arguments to the URL:
A service that takes 3 parameters:
ra, dec, radius
http://data.archive.edu/cgi-bin/search?ra=12.32&dec=-10.3&radius=0.1
When the service is invoked as a POST, the encoded list of parameters
are uploaded to the service as the HTTP Message Body.
POST /cgi-bin/search
User-Agent: Python script
Content-Type: application/x-www-form-urlencoded
Content-Lenth: 29
ra=12.32&dec=-10.3&radius=0.1
The vs:ParamHTTP type is intended for (but not limited
to) use in describing an interface within a VOResource description of
a service capability (as described in [VOR],
section 2.2.2); that is, it can be invoked via the
xsi:type attribute on an <interface>
element.
<xs:complexType name="ParamHTTP">
<xs:complexContent>
<xs:extension base="vr:Interface">
<xs:sequence>
<xs:element name="queryType" type="vs:HTTPQueryType"
minOccurs="0" maxOccurs="2"/>
<xs:element name="resultType" type="xs:token"
minOccurs="0" maxOccurs="1"/>
<xs:element name="param" type="vs:InputParam" minOccurs="0"
maxOccurs="unbounded"/>
<xs:element name="testQuery" type="xs:string" minOccurs="0"
maxOccurs="unbounded"/>
</xs:sequence>
</xs:extension>
</xs:complexContent>
</xs:complexType>
The extension metadata defined in the schema definition above are all
optional. Nevertheless, even when an <interface>
instance does not include any of these extended child elements, the
use of xsi:type="vs:ParamHTTP" indicates that the interface
accessed via the URL given by the <accessURL>
element complies with the general parameter-based protocol described
in this section.
| vs:ParamHTTP Extension Metadata Elements |
|---|
| Element | Definition |
|---|
| queryType |
| Value type: |
string with controlled values:
vs:HTTPQueryType |
| Semantic Meaning: |
The type of HTTP request
supported by the interface, either GET or POST. |
| Occurrences: |
optional; 2 occurrences are allowed to
indicate that both GET and POST are supported |
| Allowed Values: |
GET or POST |
|
| resultType |
| Value type: |
a string in MIME type format:
xs:token |
| Semantic Meaning: |
The MIME type of a document returned in the HTTP response. |
| Occurrences: |
optional |
|
| param |
| Value type: |
composite:
vs:InputParam
|
| Semantic Meaning: |
a description of an input parameter
that can be provided as a name=value argument to
the service. |
| Occurrences: |
optional; multiple occurrences allowed |
| Comments: |
See section 3.5 for the
description of this element's contents. |
|
| testQuery |
| Value type: |
a string in MIME type format:
xs:token |
| Semantic Meaning: |
an ampersand-delimited list of
arguments that can be used to test this service
interface; when provided as the input to this interface,
it will produce a legal, non-null response. |
| Occurrences: |
optional; multiple occurrences allowed |
| Comments: |
When the interface supports GET, then the full
query URL is formed by the concatonation of the
base URL (given by the accessURL) and the value
given by this testQuery element. |
|
A important intended use of the vs:ParamHTTP type is
describing the interface of an IVOA standard service protocol
of the "simple" variety, such as the Simple Image Access Protocol
[SIA]. In particular, it is recommended that
specifications that define how a standard service is registered in a
registry require the use of the vs:ParamHTTP
interface type when it is applicable.
Normally, a VOResource
description indicates its support for a standard protocol with
<capability> element having a
standardID attribute set to specific URI representing the
standard. The standard will usually spell out the HTTP query type,
the returned MIME type, and input parameters required for compliance;
therefore, it is not necessary that the vs:ParamHTTP
description provide any of the optional extended metadata, as they are
already implied by the standardID. The description need
only reflect the optional or locally unique features of the
interface. In particular, description may include
- a
<queryType> element for a type that is not
required by the standard (as long as the required query type is
supported as well),
-
<param> elements for any optional parameters
or local extended parameters (when allowed by the standard).
Of course, listing required parameters is always allowed, even when
describing a standard interface as long as these are consistent with
the service specification and the corresponding <param>
elements include the attribute use="required" (see
3.5.1). The <param>
elements for custom parameters that are not part of the standard (but
are rather local customizations) should include the attribute
std="false".
3.5. Data Parameters
The VODataService schema provides several element types for describing
different kinds of data parameters used in datasets and services,
including service input parameters and table columns. The parameter
types allow one to fully describe a parameter in terms of metadata
that includes name, data type, and meaning.
All the VODataService parameter types derive from a base type called
vs:BaseParam which defines all the common parameter
metadata except the data type.
<xs:complexType name="BaseParam">
<xs:sequence>
<xs:element name="name" type="xs:token" minOccurs="0"/>
<xs:element name="description" type="xs:token" minOccurs="0"/>
<xs:element name="unit" type="xs:token" minOccurs="0"/>
<xs:element name="ucd" type="xs:token" minOccurs="0"/>
<xs:element name="utype" type="xs:token" minOccurs="0"/>
</xs:sequence>
<xs:anyAttribute namespace="##other" />
</xs:complexType>
| vs:BaseParam Metadata Elements |
|---|
| Element | Definition |
|---|
| name |
| Value type: |
string: xs:token |
| Semantic Meaning: |
The name of the column. |
| Occurrences: |
optional |
|
| description |
| Value type: |
string: xs:token |
| Semantic Meaning: |
a free-text description of the column's contents |
| Occurrences: |
optional |
|
| unit |
| Value type: |
string: xs:token |
| Semantic Meaning: |
the unit associated with
all values associated with this parameter or table column. |
| Occurrences: |
optional |
|
| ucd |
| Value type: |
string: xs:token |
| Semantic Meaning: |
the name of a unified content descriptor that
describes the scientific content of the parameter. |
| Occurrences: |
optional |
| Comments: |
There are no requirements for compliance with any
particular UCD standard. The format of the UCD can
be used to distinguish between UCD1, UCD1+, and
SIA-UCD. See [UCD] for the
latest IVOA standard set. |
|
| utype |
| Value type: |
string: xs:token |
| Semantic Meaning: |
an identifier for a concept in a data model that
the data in this schema as a whole represent. |
| Occurrences: |
optional |
| Comments: |
The format defined in the VOTable standard, section 4.1
[VOTable] is strongly
recommended; see "Note on UType
Format" above. |
|
Leaving the data type metadatum out of vs:BaseParam
allows the different kinds of parameters derived from
vs:BaseParam to restrict the allowed data types to
specific sets. The subsections below describe the different data
types associated with input parameters
(vs:InputParam) and table
columns (vs:TableParam). The
XML types associated with their <dataType> elements
derive from a common parent, vs:DataType.
<xs:complexType name="DataType">
<xs:simpleContent>
<xs:extension base="xs:token">
<xs:attribute name="arraysize" type="vs:ArrayShape" default="1"/>
<xs:attribute name="delim" type="xs:string" default=" "/>
<xs:attribute name="extendedType" type="xs:string"/>
<xs:attribute name="extendedSchema" type="xs:anyURI"/>
<xs:anyAttribute namespace="##other" />
</xs:extension>
</xs:simpleContent>
</xs:complexType>
The content of a data type element of this type is the name of the
data type for the current parameter. When the element is explicitly
a vs:DataType (as opposed to one of its derived types),
there are no restrictions on the names that may be included.
A data type description can be augmented via a common set of
vs:DataType attributes, defined below. The
arraysize attribute indicates the parameter is an array
of values of the named type. Its value describes the shape of the
array, and the delim attribute may be used to indicate
the delimiter that should appear between elements of an array value.
Depending on the application context, these attribute may not be
enough to effectively parse the array values, in which case more
information must be brought to bear either through assumptions about
a particular derived vs:DataType or through additional
attributes.
More descriptive information about the type can be provided via
extendedType and extendedSchema, which
provide an alternate data type name. It's expected that this name
will only be understood by a special subset of applications. The name
given in the element content, then, represents a more commonly
understood "fall-back" type. Arbitrary information can also be
provided via any prefix-qualified, globally defined attribute drawn
from an XML Schema other than VODataService (by virtue of the
xs:anyAttribute specification shown
above).
| vs:DataType Attributes |
|---|
| Attribute | Definition |
|---|
arraysize |
| Value type: |
the VOTable arraysize
format (vs:ArrayShape):
LxMxN...,
where each x-delimited positive integer
is a length along a dimension of a multi-dimensional array. A
single integer indicates a one dimensional array.
Instead of an integer, the last length can be set to
"*" which indicates a variable length.
|
| Semantic Meaning: |
The attribute's presence
indicates that parameter holds an array values; the
attribute's value indicates the length of the array along
each dimension of the multi-dimensional array. |
| Occurrences: |
optional |
| Default Value: |
1 (i.e. the parameter value
is scalar) |
|
delim |
| Value type: |
string: xs:string |
| Semantic Meaning: |
the string that is used to delimit
element of an array value when arraysize is
not "1". |
| Occurrences: |
optional. |
| Comments: |
Unless specifically
disallowed by the context, applications should allow
optional spaces to appear in an actual data value
before and after the delimiter (e.g. "1, 5" when delim=","). |
|
extendedType |
| Value type: |
string: xs:string. |
| Semantic Meaning: |
The data value represented by this type can be
interpreted as of a custom type identified by
the value of this attribute. |
| Occurrences: |
optional |
| Comments: |
The name implies a particular expected format for
the data value that can be parsed into a value in
memory.
If an application does not recognize this
extendedType, it should attempt to handle value
assuming the type given by the element's value.
"string" (or its equivalent) is a recommended
default type.
This element may make use of the extendedSchema
attribute and/or any arbitrary (qualified)
attribute to refine the identification of the
type.
|
|
extendedSchema |
| Value type: |
URI: xs:anyURI. |
| Semantic Meaning: |
An identifier for the
schema that the value given by the extended
attribute is drawn from. |
| Occurrences: |
optional |
| Comments: |
This attribute is normally ignored if the
extended element is not present.
|
|
Note that in the derived parameter description types described below,
the <dataType> element is optional. Its absence
from the parameter description does not mean that the
parameter can support any data type; rather, it means that the data
type simply has not been provided (which may limit what an application
can do with the parameter). If a parameter can truly support any data
type, the vs:BaseParam type can be used directly when the
context permits.
3.5.1. Input Parameters
Actual parameters are normally described with types derived from
vs:BaseParam. The vs:InputParam is intended
for describing an input parameter to a service or function. The
allowed data type names (given in the metadata table below) do not
imply a size or precise format; rather, they are intended to be
sufficient for describing an input paramter to a simple REST-like
service or a function in a weakly-typed (e.g. scripting) language.
<xs:complexType name="InputParam">
<xs:complexContent>
<xs:extension base="vs:BaseParam">
<xs:sequence>
<xs:element name="dataType" type="vs:SimpleDataType"
minOccurs="0"/>
</xs:sequence>
<xs:attribute name="use" type="vs:ParamUse" default="optional"/>
<xs:attribute name="std" type="xs:boolean" default="true"/>
</xs:extension>
</xs:complexContent>
</xs:complexType>
By fixing the <dataType> child element to that of the
vs:SimpleDataType, the possible types are restricted to
predefined set appropriate for input parameters.
| vs:InputParam Extension Metadata Elements |
|---|
| Element | Definition |
|---|
| dataType |
| Value type: |
string with optional attributes:
vs:SimpleDataType |
| Semantic Meaning: |
a type of data contained in the column. |
| Occurrences: |
optional |
| Allowed Values: |
The following type names correspond to
the same data types defined in the VOTable standard
[VOTable]:
boolean,
char,
integer,
real, and
complex.
The additional type, string, is
equivalent to char when the attribute
arrayshape="*". |
|
The vs:InputParam type accepts two attributes that
indicate the role that the parameter plays as input to the service or
function:
| vs:InputParam Attributes |
|---|
| Attribute | Definition |
|---|
use |
| Value type: |
string with controlled values: vs:ParamUse
|
| Semantic Meaning: |
An indication of whether this parameter is
required to be provided for the application
or service to work properly. |
| Occurrences: |
optional |
| Allowed Values: |
required | |
the parameter must be provided. |
optional | |
the parameter need not be provided (default). |
|
|
std |
| Value type: |
true or false (xs:boolean) |
| Semantic Meaning: |
If true, the meaning and behavior of this parameter is
reserved and defined by a standard interface. If
false, it represents an implementation-specific
parameter that effectively extends the behavior of the
service or application. The default is true.
|
| Occurrences: |
optional |
|
A description
of an input parameter that might appear inside an
vs:ParamHTTP interface description. As noted in
section 3.4, a
<param>
element uses the
vs:InputParam type to describe itself.
<param use="required">
<name> radius </name>
<description>
search radius; returned objects are restricted to fall
within this angular distance of the search position.
</description>
<ucd> phys.angSize </ucd>
<dataType> real </dataType>
</param>
3.5.2. Table Columns
The vs:TableParam is also derived from
vs:BaseParam, and is designed for describing a column of
a table.
<xs:complexType name="TableParam">
<xs:complexContent>
<xs:extension base="vs:BaseParam">
<xs:sequence>
<xs:element name="dataType" type="vs:TableDataType"
minOccurs="0"/>
<xs:element name="flag" type="xs:token"
minOccurs="0" maxOccurs="unbounded"/>
</xs:sequence>
<xs:attribute name="std" type="xs:boolean"/>
</xs:extension>
</xs:complexContent>
</xs:complexType>
<xs:complexType name="TableDataType" abstract="true">
<xs:simpleContent>
<xs:extension base="vs:DataType"/>
</xs:simpleContent>
</xs:complexType>
A table column's data type is indicated with the <dataType>
element with a name drawn from a standard set of names. The
vs:TableParam type is not restricted to a single standard
set, and the VODataService schema defines two standard sets: one
corresponding to VOTable data types [VOTable]
and one for Table Access Protocol types. Because
its XML type, vs:TableDataType is abstract, the
<dataType> element MUST include an
xsi:type attribute to indicate which standard set of type
names is being used.
A declination column called "Dec" is
defined to have the VOTable-defined type, double
<column>
<name> Dec </name>
<description> the J2000 declination of the object </description>
<ucd> pos.eq.dec </ucd>
<dataType xsi:type="vs:VOTableType"> double </dataType>
</column>
| vs:TableParam Extension Metadata Elements |
|---|
| Element | Definition |
|---|
| dataType |
| Value type: |
string with a required xsi:type
attribute and additional optional attributes:
vs:TableDataType |
| Semantic Meaning: |
a type of data contained in the column. |
| Occurrences: |
optional |
| Allowed Values: |
The allowed type names are determined
by value of the xsi:type; see
section 3.5.3 below. |
|
| flag |
| Value type: |
string with optional attributes:
vs:TableDataType |
| Semantic Meaning: |
a keyword representing
traits of the column. |
| Occurrences: |
optional; multiple occurrences allowed |
| Recommended Values: |
indexed | |
The column has an index on it
for faster search against its values. |
primary | |
The values column in the column
represents in total or in part a primary key
for its table. |
nullable | |
the column may contain null or empty values. |
Other values are allowed.
|
|
3.5.3. Table Column Data Types
The VODataService schema defines two XML types that derive from
vs:TableDataType: vs:VOTableType and
vs:TAPType.
| Data Types derived from vs:TableDataType |
|---|
Value for
xsi:type | Definition |
|---|
| vs:VOTableType |
| Semantic Meaning: |
data types that correspond
to the parameter and column types defined in the
VOTable schema [VOTable]. |
| Allowed Values: |
boolean,
bit,
unsignedByte,
short,
int,
long,
char,
unicodeChar,
float,
double,
floatComplex, and
doubleComplex. String values of
arbitrary length are represent by a value of
char with arraysize="*" |
|
| vs:TAPType |
| Semantic Meaning: |
data types that correspond
column types defined in the Table Access Protocol (v1.0)
[TAP]. |
| Allowed Values: |
BOOLEAN,
SMALLINT,
INTEGER,
BIGINT,
REAL,
DOUBLE,
TIMESTAMP,
CHAR,
VARCHAR,
BINARY,
VARBINARY,
POINT,
REGION,
CLOB, and
BLOB. String values are represented via
VARCHAR.
|
|
The vs:TAPType XML type provides an additional attribute,
size, corresponding to the "size" column from the
TAP_SCHEMA.columns defined by TAP:
| Additional Attribute for the vs:TAPType
set of column data types |
|---|
| Attribute | Definition |
|---|
size |
| Value type: |
a positive integer:
xs:positiveInteger
|
| Semantic Meaning: |
The length of the variable-length
data type. |
| Occurrences: |
optional |
| Comments: |
In the context of TAP, this attribute is only meaning when
the data type is CHAR or BINARY; see
discussion below.
|
|
a representation of a string type using the
vs:VOTableType set of types:
<column>
<name> id </name>
<description> the object identifier </description>
<ucd> meta.id </ucd>
<dataType xsi:type="vs:VOTableType" arraysize="*"> char </dataType>
</column>
the same column described using the
vs:TAPType set of types:
<column>
<name> id </name>
<description> the object identifier </description>
<ucd> meta.id </ucd>
<dataType xsi:type="vs:TAPType"> VARCHAR </dataType>
</column>
the same column again described using the
vs:TAPType set of types, assuming a fixed-length string:
<column>
<name> id </name>
<description> the object identifier </description>
<ucd> meta.id </ucd>
<dataType xsi:type="vs:TAPType" size="8" > CHAR </dataType>
</column>
In general, the vs:TableParam's <dataType>
can support any non-abstract type legally derived from
vs:TableDataType. However, in the context of a
vs:DataCollection or vs:CatalogService
resource description, it is strongly recommended that either
vs:VOTableType or vs:TAPType (or some other IVOA
standard type derived from vs:TableDataType) be used to
ensure maximum interoperability. When the actual column type is not
well matched to a type from one of these standard sets, authors are
encouraged to use the extendedType attribute to refer to
a more specific type. Note that the TAP standard
[TAP] defines an explicit mapping between
TAP_SCHEMA types and VOTable types. Thus, in the context of a
vs:CatalogService resource description that supports a
TAP capability (perhaps in addition to other catalog services like
Simple Cone Search [SCS]), use of the
vs:TAPType data type is preferred.
- Note:
- The motivation for providing two standard data type sets,
vs:VOTableType and vs:TAPType, is to maximize
the ease of generating the table description, particular as
part of the VO Standard Interface [VOSI]
and for legacy services. The table description for
"stand-alone" SIA, SCS, and SSA services can be readily
generated using the vs:VOTableType data types from
these interface's respective metadata queries. Newer services
supporting TAP could generate its description using its
TAP_SCHEMA queries.
The motivation for specifying a column's data type using the
xsi:type mechanism is mainly to allow for the
possibility that the official TAP data types will evolve. This
allows the IVOA to define new data type sets without updating
the VODataService standard. Using non-IVOA-standardized data
type names is expected to undermine interoperability and so is
therefore discouraged.
|
Appendix A: The VODataService XML Schema
<?xml version="1.0" encoding="UTF-8"?>
<xs:schema targetNamespace="http://www.ivoa.net/xml/VODataService/v1.1"
xmlns:xs="http://www.w3.org/2001/XMLSchema"
xmlns:vr="http://www.ivoa.net/xml/VOResource/v1.0"
xmlns:vs="http://www.ivoa.net/xml/VODataService/v1.1"
xmlns:stc="http://www.ivoa.net/xml/STC/stc-v1.30.xsd"
xmlns:vm="http://www.ivoa.net/xml/VOMetadata/v0.1"
elementFormDefault="unqualified" attributeFormDefault="unqualified"
version="1.1pr2">
<xs:annotation>
<xs:appinfo>
<vm:schemaName>VODataService</vm:schemaName>
<vm:schemaPrefix>xs</vm:schemaPrefix>
<vm:targetPrefix>vs</vm:targetPrefix>
</xs:appinfo>
<xs:documentation>
An extension to the core resource metadata (VOResource) for
describing data collections and services.
</xs:documentation>
</xs:annotation>
<xs:import namespace="http://www.ivoa.net/xml/VOResource/v1.0"
schemaLocation="http://www.ivoa.net/xml/VOResource/v1.0"/>
<xs:import namespace="http://www.ivoa.net/xml/STC/stc-v1.30.xsd"
schemaLocation="http://www.ivoa.net/xml/STC/stc-v1.30.xsd"/>
<xs:complexType name="DataCollection">
<xs:annotation>
<xs:documentation>
A logical grouping of data which, in general, is composed of one
or more accessible datasets. A collection can contain any
combination of images, spectra, catalogs, or other data.
</xs:documentation>
<xs:documentation>
(A dataset is a collection of digitally-encoded data that
is normally accessible as a single unit, e.g. a file.)
</xs:documentation>
</xs:annotation>
<xs:complexContent>
<xs:extension base="vr:Resource">
<xs:sequence>
<xs:element name="facility" type="vr:ResourceName"
minOccurs="0" maxOccurs="unbounded">
<xs:annotation>
<xs:appinfo>
<vm:dcterm>Subject</vm:dcterm>
</xs:appinfo>
<xs:documentation>
the observatory or facility used to collect the data
contained or managed by this resource.
</xs:documentation>
</xs:annotation>
</xs:element>
<xs:element name="instrument" type="vr:ResourceName"
minOccurs="0" maxOccurs="unbounded">
<xs:annotation>
<xs:appinfo>
<vm:dcterm>Subject</vm:dcterm>
<vm:dcterm>Subject.Instrument</vm:dcterm>
</xs:appinfo>
<xs:documentation>
the Instrument used to collect the data contain or
managed by a resource.
</xs:documentation>
</xs:annotation>
</xs:element>
<xs:element name="rights" type="vr:Rights"
minOccurs="0" maxOccurs="unbounded">
<xs:annotation>
<xs:appinfo>
<vm:dcterm>Rights</vm:dcterm>
</xs:appinfo>
<xs:documentation>
Information about rights held in and over the resource.
</xs:documentation>
<xs:documentation>
This should be repeated for all Rights values that apply.
</xs:documentation>
</xs:annotation>
</xs:element>
<xs:element name="format" type="vs:Format"
minOccurs="0" maxOccurs="unbounded">
<xs:annotation>
<xs:documentation>
The physical or digital manifestation of the information
supported by a resource.
</xs:documentation>
<xs:documentation>
MIME types should be used for network-retrievable, digital
data. Non-MIME type values are used for media that cannot
be retrieved over the network--e.g. CDROM, poster, slides,
video cassette, etc.
</xs:documentation>
</xs:annotation>
</xs:element>
<xs:element name="coverage" type="vs:Coverage" minOccurs="0">
<xs:annotation>
<xs:documentation>
Extent of the content of the resource over space, time,
and frequency.
</xs:documentation>
</xs:annotation>
</xs:element>
<xs:element name="tableset" type="vs:TableSet" minOccurs="0">
<xs:annotation>
<xs:documentation>
A description of the tables that are part of this
collection.
</xs:documentation>
<xs:documentation>
Each schema name and each table name must be
unique within this tableset.
</xs:documentation>
</xs:annotation>
<xs:unique name="DataCollection-schemaName">
<xs:selector xpath="schema" />
<xs:field xpath="name" />
</xs:unique>
<xs:unique name="DataCollection-tableName">
<xs:selector xpath="schema/table" />
<xs:field xpath="name" />
</xs:unique>
</xs:element>
<xs:element name="accessURL" type="vr:AccessURL" minOccurs="0">
<xs:annotation>
<xs:documentation>
The URL that can be used to download the data contained in
this data collection.
</xs:documentation>
</xs:annotation>
</xs:element>
</xs:sequence>
</xs:extension>
</xs:complexContent>
</xs:complexType>
<xs:complexType name="Coverage">
<xs:annotation>
<xs:documentation>
A description of how a resource's contents or behavior maps
to the sky, to time, and to frequency space, including
coverage and resolution.
</xs:documentation>
</xs:annotation>
<xs:sequence>
<xs:element ref="stc:STCResourceProfile" minOccurs="0">
<xs:annotation>
<xs:documentation>
The STC description of the location of the resource's
data (or behavior on data) on the sky, in time, and in
frequency space, including resolution.
</xs:documentation>
<xs:documentation>
In general, this description should be approximate; a
more precise description can be provided by the
footprint service.
</xs:documentation>
</xs:annotation>
</xs:element>
<xs:element name="footprint" type="vs:ServiceReference"
minOccurs="0">
<xs:annotation>
<xs:documentation>
a reference to a footprint service for retrieving
precise and up-to-date description of coverage.
</xs:documentation>
<xs:documentation>
the ivo-id attribute refers to a Service record
that describes the Footprint capability. That is,
the record will have a capability element describing
the service. The resource refered to may be the
current one.
</xs:documentation>
</xs:annotation>
</xs:element>
<xs:element name="waveband" type="vs:Waveband"
minOccurs="0" maxOccurs="unbounded">
<xs:annotation>
<xs:appinfo>
<vm:dcterm>Coverage.Spectral</vm:dcterm>
</xs:appinfo>
<xs:documentation>
a named spectral region of the electro-magnetic spectrum
that the resource's spectral coverage overlaps with.
</xs:documentation>
</xs:annotation>
</xs:element>
<xs:element name="regionOfRegard" type="xs:float" minOccurs="0">
<xs:annotation>
<xs:appinfo>
<vm:dcterm>Coverage.RegionOfRegard</vm:dcterm>
</xs:appinfo>
<xs:documentation>
a single numeric value representing the angle, given
in decimal degrees, by which a positional query
against this resource should be "blurred" in order
to get an appropriate match.
</xs:documentation>
<xs:documentation>
In the case of image repositories, it might refer to
a typical field-of-view size, or the primary beam
size for radio aperture synthesis data. In the case
of object catalogs RoR should normally be the
largest of the typical size of the objects, the
astrometric errors in the positions, or the
resolution of the data.
</xs:documentation>
</xs:annotation>
</xs:element>
</xs:sequence>
</xs:complexType>
<xs:complexType name="ServiceReference">
<xs:annotation>
<xs:documentation>
the service URL for a potentially registerd service. That is,
if an IVOA identifier is also provided, then the service is
described in a registry.
</xs:documentation>
</xs:annotation>
<xs:simpleContent>
<xs:extension base="xs:anyURI">
<xs:attribute name="ivo-id" type="vr:IdentifierURI">
<xs:annotation>
<xs:documentation>
The URI form of the IVOA identifier for the service
describing the capability refered to by this element.
</xs:documentation>
</xs:annotation>
</xs:attribute>
</xs:extension>
</xs:simpleContent>
</xs:complexType>
<xs:simpleType name="Waveband">
<xs:restriction base="xs:token">
<xs:enumeration value="Radio">
<xs:annotation>
<xs:documentation>
wavelength >= 10 mm; frequency <= 30 GHz.
</xs:documentation>
</xs:annotation>
</xs:enumeration>
<xs:enumeration value="Millimeter">
<xs:annotation>
<xs:documentation>
0.1 mm <= wavelength <= 10 mm;
3000 GHz >= frequency >= 30 GHz.
</xs:documentation>
</xs:annotation>
</xs:enumeration>
<xs:enumeration value="Infrared">
<xs:annotation>
<xs:documentation>
1 micron <= wavelength <= 100 micons
</xs:documentation>
</xs:annotation>
</xs:enumeration>
<xs:enumeration value="Optical">
<xs:annotation>
<xs:documentation>
0.3 microns <= wavelength <= 1 micon;
300 nm <= wavelength <= 1000 nm;
3000 Angstroms <= wavelength <= 10000 Angstroms
</xs:documentation>
</xs:annotation>
</xs:enumeration>
<xs:enumeration value="UV">
<xs:annotation>
<xs:documentation>
0.1 microns <= wavelength <= 0.3 micon;
1000 nm <= wavelength <= 3000 nm;
1000 Angstroms <= wavelength <= 30000 Angstroms
</xs:documentation>
</xs:annotation>
</xs:enumeration>
<xs:enumeration value="EUV">
<xs:annotation>
<xs:documentation>
100 Angstroms <= wavelength <= 1000 Angstroms;
12 eV <= energy <= 120 eV
</xs:documentation>
</xs:annotation>
</xs:enumeration>
<xs:enumeration value="X-ray">
<xs:annotation>
<xs:documentation>
0.1 Angstroms <= wavelength <= 100 Angstroms;
0.12 keV <= energy <= 120 keV
</xs:documentation>
</xs:annotation>
</xs:enumeration>
<xs:enumeration value="Gamma-ray">
<xs:annotation>
<xs:documentation>
energy >= 120 keV
</xs:documentation>
</xs:annotation>
</xs:enumeration>
</xs:restriction>
</xs:simpleType>
<xs:complexType name="TableSet">
<xs:annotation>
<xs:documentation>
The set of tables hosted by a resource.
</xs:documentation>
</xs:annotation>
<xs:sequence>
<xs:element name="schema" type="vs:TableSchema"
minOccurs="1" maxOccurs="unbounded">
<xs:annotation>
<xs:documentation>
A named description of a set of logically related tables.
</xs:documentation>
<xs:documentation>
The name given by the "name" child element must
be unique within this TableSet instance. If there is
only one schema in this set and/or there's no locally
appropriate name to provide, the name can be set to
"default".
</xs:documentation>
<xs:documentation>
This aggregation does not need to map to an
actual database, catalog, or schema, though the
publisher may choose to aggregate along such
designations, or particular service protocol may
recommend it.
</xs:documentation>
</xs:annotation>
</xs:element>
</xs:sequence>
<xs:anyAttribute namespace="##other" />
</xs:complexType>
<xs:complexType name="TableSchema">
<xs:annotation>
<xs:documentation>
A detailed description of a logically-related set of tables
</xs:documentation>
</xs:annotation>
<xs:sequence>
<xs:element name="name" type="xs:token" minOccurs="1" maxOccurs="1">
<xs:annotation>
<xs:documentation>
A name for the set of tables.
</xs:documentation>
<xs:documentation>
This is used to uniquely identify the table set among
several table sets. If a title is not present, this
name can be used for display purposes.
</xs:documentation>
<xs:documentation>
If there is no appropriate logical name associated with
this set, the name should be explicitly set to
"default".
</xs:documentation>
</xs:annotation>
</xs:element>
<xs:element name="title" type="xs:token" minOccurs="0">
<xs:annotation>
<xs:documentation>
a descriptive, human-interpretable name for the table set.
</xs:documentation>
<xs:documentation>
This is used for display purposes. There is no requirement
regarding uniqueness. It is useful when there are
multiple schemas in the context (e.g. within a
tableset; otherwise, the resource title could be
used instead).
</xs:documentation>
</xs:annotation>
</xs:element>
<xs:element name="description" type="xs:token"
minOccurs="0" maxOccurs="1">
<xs:annotation>
<xs:documentation>
A free text description of the tableset that should
explain in general how all of the tables are related.
</xs:documentation>
</xs:annotation>
</xs:element>
<xs:element name="utype" type="xs:token" minOccurs="0">
<xs:annotation>
<xs:documentation>
an identifier for a concept in a data model that
the data in this schema as a whole represent.
</xs:documentation>
<xs:documentation>
The format defined in the VOTable standard is strongly
recommended.
</xs:documentation>
</xs:annotation>
</xs:element>
<xs:element name="table" type="vs:Table"
minOccurs="0" maxOccurs="unbounded">
<xs:annotation>
<xs:documentation>
A description of one of the tables that makes up the set.
</xs:documentation>
<xs:documentation>
The table names for the table should be unique.
</xs:documentation>
</xs:annotation>
</xs:element>
</xs:sequence>
<xs:anyAttribute namespace="##other" />
</xs:complexType>
<xs:complexType name="Format">
<xs:simpleContent>
<xs:extension base="xs:token">
<xs:attribute name="isMIMEType" type="xs:boolean" default="false">
<xs:annotation>
<xs:documentation>
if true, then the content is a MIME Type
</xs:documentation>
</xs:annotation>
</xs:attribute>
</xs:extension>
</xs:simpleContent>
</xs:complexType>
<xs:complexType name="DataService">
<xs:annotation>
<xs:documentation>
A service for accessing astronomical data
</xs:documentation>
</xs:annotation>
<xs:complexContent>
<xs:extension base="vr:Service">
<xs:sequence>
<xs:element name="facility" type="vr:ResourceName"
minOccurs="0" maxOccurs="unbounded">
<xs:annotation>
<xs:appinfo>
<vm:dcterm>Subject</vm:dcterm>
</xs:appinfo>
<xs:documentation>
the observatory or facility used to collect the data
contained or managed by this resource.
</xs:documentation>
</xs:annotation>
</xs:element>
<xs:element name="instrument" type="vr:ResourceName"
minOccurs="0" maxOccurs="unbounded">
<xs:annotation>
<xs:appinfo>
<vm:dcterm>Subject</vm:dcterm>
<vm:dcterm>Subject.Instrument</vm:dcterm>
</xs:appinfo>
<xs:documentation>
the Instrument used to collect the data contain or
managed by a resource.
</xs:documentation>
</xs:annotation>
</xs:element>
<xs:element name="coverage" type="vs:Coverage" minOccurs="0">
<xs:annotation>
<xs:documentation>
Extent of the content of the resource over space, time,
and frequency.
</xs:documentation>
</xs:annotation>
</xs:element>
</xs:sequence>
</xs:extension>
</xs:complexContent>
</xs:complexType>
<xs:complexType name="ParamHTTP">
<xs:annotation>
<xs:documentation>
A service invoked via an HTTP Query (either Get or Post)
with a set of arguments consisting of keyword name-value pairs.
</xs:documentation>
<xs:documentation>
Note that the URL for help with this service can be put into
the Service/ReferenceURL element.
</xs:documentation>
</xs:annotation>
<xs:complexContent>
<xs:extension base="vr:Interface">
<xs:sequence>
<xs:element name="queryType" type="vs:HTTPQueryType"
minOccurs="0" maxOccurs="2">
<xs:annotation>
<xs:documentation>
The type of HTTP request, either GET or POST.
</xs:documentation>
<xs:documentation>
The service may indicate support for both GET
and POST by providing 2 queryType elements, one
with GET and one with POST.
</xs:documentation>
</xs:annotation>
</xs:element>
<xs:element name="resultType" type="xs:token"
minOccurs="0" maxOccurs="1">
<xs:annotation>
<xs:documentation>
The MIME type of a document returned in the HTTP response.
</xs:documentation>
</xs:annotation>
</xs:element>
<xs:element name="param" type="vs:InputParam" minOccurs="0"
maxOccurs="unbounded">
<xs:annotation>
<xs:documentation>
a description of a input parameter that can be
provided as a name=value argument to the service.
</xs:documentation>
</xs:annotation>
</xs:element>
<xs:element name="testQuery" type="xs:string" minOccurs="0"
maxOccurs="unbounded">
<xs:annotation>
<xs:documentation>
a ampersand-delimited list of arguments that
can be used to test this service interface;
when provided as the input to this interface,
it will produce a legal, non-null response.
</xs:documentation>
<xs:documentation>
When then interface supports GET, then the full
query URL is formed by the concatonation of the
base URL (given by the accessURL) and the value
given by this testQuery element.
</xs:documentation>
</xs:annotation>
</xs:element>
</xs:sequence>
</xs:extension>
</xs:complexContent>
</xs:complexType>
<xs:simpleType name="HTTPQueryType">
<xs:annotation>
<xs:documentation>
The type of HTTP request, either GET or POST.
</xs:documentation>
</xs:annotation>
<xs:restriction base="xs:token">
<xs:enumeration value="GET"/>
<xs:enumeration value="POST"/>
</xs:restriction>
</xs:simpleType>
<xs:complexType name="CatalogService">
<xs:annotation>
<xs:documentation>
A service that interacts with with astronomical data
through one or more specified tables.
</xs:documentation>
<xs:documentation>
A table with sky coverage typically have columns that give
longitude-latitude positions in some coordinate system.
</xs:documentation>
</xs:annotation>
<xs:complexContent>
<xs:extension base="vs:DataService">
<xs:sequence>
<xs:element name="tableset" type="vs:TableSet" minOccurs="0">
<xs:annotation>
<xs:documentation>
A description of the tables that are accessible
through this service.
</xs:documentation>
<xs:documentation>
Each schema name and each table name must be
unique within this tableset.
</xs:documentation>
</xs:annotation>
<xs:unique name="CatalogService-schemaName">
<xs:selector xpath="schema" />
<xs:field xpath="name" />
</xs:unique>
<xs:unique name="CatalogService-tableName">
<xs:selector xpath="schema/table" />
<xs:field xpath="name" />
</xs:unique>
</xs:element>
</xs:sequence>
</xs:extension>
</xs:complexContent>
</xs:complexType>
<xs:complexType name="Table">
<xs:sequence>
<xs:element name="name" type="xs:token"
minOccurs="1" maxOccurs="1">
<xs:annotation>
<xs:documentation>
the fully qualified name of the table. This name
should include all catalog or schema prefixes
needed to sufficiently uniquely distinguish it in a
query.
</xs:documentation>
<xs:documentation>
In general, the format of the qualified name may
depend on the context; however, when the
table is intended to be queryable via ADQL, then the
catalog and schema qualifiers are delimited from the
table name with dots (.).
</xs:documentation>
</xs:annotation>
</xs:element>
<xs:element name="title" type="xs:token" minOccurs="0">
<xs:annotation>
<xs:documentation>
a descriptive, human-interpretable name for the table.
</xs:documentation>
<xs:documentation>
This is used for display purposes. There is no requirement
regarding uniqueness.
</xs:documentation>
</xs:annotation>
</xs:element>
<xs:element name="description" type="xs:token" minOccurs="0">
<xs:annotation>
<xs:documentation>
a free-text description of the table's contents
</xs:documentation>
</xs:annotation>
</xs:element>
<xs:element name="utype" type="xs:token" minOccurs="0">
<xs:annotation>
<xs:documentation>
an identifier for a concept in a data model that
the data in this table represent.
</xs:documentation>
<xs:documentation>
The format defined in the VOTable standard is highly
recommended.
</xs:documentation>
</xs:annotation>
</xs:element>
<xs:element name="column" type="vs:TableParam"
minOccurs="0" maxOccurs="unbounded">
<xs:annotation>
<xs:documentation>
a description of a table column.
</xs:documentation>
</xs:annotation>
</xs:element>
<xs:element name="foreignKey" type="vs:ForeignKey"
minOccurs="0" maxOccurs="unbounded" >
<xs:annotation>
<xs:documentation>
a description of a foreign keys, one or more columns
from the current table that can be used to join with
another table.
</xs:documentation>
</xs:annotation>
</xs:element>
</xs:sequence>
<xs:attribute name="type" type="xs:string">
<xs:annotation>
<xs:documentation>
a name for the role this table plays. Recognized
values include "output", indicating this table is output
from a query; "base_table", indicating a table
whose records represent the main subjects of its
schema; and "view", indicating that the table represents
a useful combination or subset of other tables. Other
values are allowed.
</xs:documentation>
</xs:annotation>
</xs:attribute>
<xs:anyAttribute namespace="##other" />
</xs:complexType>
<xs:complexType name="BaseParam">
<xs:annotation>
<xs:documentation>
a description of a parameter that places no restriction on
the parameter's data type.
</xs:documentation>
<xs:documentation>
As the parameter's data type is usually important, schemas
normally employ a sub-class of this type (e.g. Param),
rather than this type directly.
</xs:documentation>
</xs:annotation>
<xs:sequence>
<xs:element name="name" type="xs:token" minOccurs="0">
<xs:annotation>
<xs:documentation>
the name of the column
</xs:documentation>
</xs:annotation>
</xs:element>
<xs:element name="description" type="xs:token" minOccurs="0">
<xs:annotation>
<xs:documentation>
a free-text description of the column's contents
</xs:documentation>
</xs:annotation>
</xs:element>
<xs:element name="unit" type="xs:token" minOccurs="0">
<xs:annotation>
<xs:documentation>
the unit associated with all values in the column
</xs:documentation>
</xs:annotation>
</xs:element>
<xs:element name="ucd" type="xs:token" minOccurs="0">
<xs:annotation>
<xs:documentation>
the name of a unified content descriptor that
describes the scientific content of the parameter.
</xs:documentation>
<xs:documentation>
There are no requirements for compliance with any
particular UCD standard. The format of the UCD can
be used to distinguish between UCD1, UCD1+, and
SIA-UCD. See
http://www.ivoa.net/Documents/latest/UCDlist.html
for the latest IVOA standard set.
</xs:documentation>
</xs:annotation>
</xs:element>
<xs:element name="utype" type="xs:token" minOccurs="0">
<xs:annotation>
<xs:documentation>
an identifier for a concept in a data model that
the data in this schema represent.
</xs:documentation>
<xs:documentation>
The format defined in the VOTable standard is highly
recommended.
</xs:documentation>
</xs:annotation>
</xs:element>
</xs:sequence>
<xs:anyAttribute namespace="##other" />
</xs:complexType>
<xs:complexType name="TableParam">
<xs:annotation>
<xs:documentation>
a description of a table parameter having a fixed data type.
</xs:documentation>
<xs:documentation>
The allowed data type names match those supported by VOTable.
</xs:documentation>
</xs:annotation>
<xs:complexContent>
<xs:extension base="vs:BaseParam">
<xs:sequence>
<xs:element name="dataType" type="vs:TableDataType"
minOccurs="0">
<xs:annotation>
<xs:documentation>
a type of data contained in the column
</xs:documentation>
</xs:annotation>
</xs:element>
<xs:element name="flag" type="xs:token"
minOccurs="0" maxOccurs="unbounded">
<xs:annotation>
<xs:documentation>
a keyword representing traits of the column.
Recognized values include "indexed", "primary", and
"nullable".
</xs:documentation>
<xs:documentation>
See the specification document for definitions
of recognized keywords.
</xs:documentation>
</xs:annotation>
</xs:element>
</xs:sequence>
<xs:attribute name="std" type="xs:boolean">
<xs:annotation>
<xs:documentation>
If true, the meaning and use of this parameter is
reserved and defined by a standard model. If false,
it represents a database-specific parameter
that effectively extends beyond the standard. If
not provided, then the value is unknown.
</xs:documentation>
</xs:annotation>
</xs:attribute>
</xs:extension>
</xs:complexContent>
</xs:complexType>
<xs:complexType name="InputParam">
<xs:annotation>
<xs:documentation>
a description of a service or function parameter having a
fixed data type.
</xs:documentation>
<xs:documentation>
The allowed data type names do not imply a size or precise
format. This type is intended to be sufficient for describing
an input parameter to a simple REST service or a function
written in a weakly-typed (e.g., scripting) language.
</xs:documentation>
</xs:annotation>
<xs:complexContent>
<xs:extension base="vs:BaseParam">
<xs:sequence>
<xs:element name="dataType" type="vs:SimpleDataType"
minOccurs="0">
<xs:annotation>
<xs:documentation>
a type of data contained in the column
</xs:documentation>
</xs:annotation>
</xs:element>
</xs:sequence>
<xs:attribute name="use" type="vs:ParamUse" default="optional">
<xs:annotation>
<xs:documentation>
An indication of whether this parameter is
required to be provided for the application
or service to work properly.
</xs:documentation>
<xs:documentation>
Allowed values are "required" and "optional".
</xs:documentation>
</xs:annotation>
</xs:attribute>
<xs:attribute name="std" type="xs:boolean" default="true">
<xs:annotation>
<xs:documentation>
If true, the meaning and behavior of this parameter is
reserved and defined by a standard interface. If
false, it represents an implementation-specific
parameter that effectively extends the behavior of the
service or application.
</xs:documentation>
</xs:annotation>
</xs:attribute>
</xs:extension>
</xs:complexContent>
</xs:complexType>
<xs:simpleType name="ParamUse">
<xs:restriction base="xs:string">
<xs:enumeration value="required">
<xs:annotation>
<xs:documentation>
the parameter is required for the application or
service to work properly.
</xs:documentation>
</xs:annotation>
</xs:enumeration>
<xs:enumeration value="optional">
<xs:annotation>
<xs:documentation>
the parameter is optional but supported by the application or
service.
</xs:documentation>
</xs:annotation>
</xs:enumeration>
<xs:enumeration value="ignored">
<xs:annotation>
<xs:documentation>
the parameter is not supported and thus is ignored by the
application or service.
</xs:documentation>
</xs:annotation>
</xs:enumeration>
</xs:restriction>
</xs:simpleType>
<xs:complexType name="DataType">
<xs:annotation>
<xs:documentation>
a type (in the computer language sense) associated with a
parameter with an arbitrary name
</xs:documentation>
<xs:documentation>
This XML type is used as a parent for defining data types
with a restricted set of names.
</xs:documentation>
</xs:annotation>
<xs:simpleContent>
<xs:extension base="xs:token">
<xs:attribute name="arraysize" type="vs:ArrayShape" default="1">
<xs:annotation>
<xs:documentation>
the shape of the array that constitutes the value
</xs:documentation>
<xs:documentation>
the default is "1"; i.e. the value is a scalar.
</xs:documentation>
</xs:annotation>
</xs:attribute>
<xs:attribute name="delim" type="xs:string" default=" ">
<xs:annotation>
<xs:documentation>
the string that is used to delimit elements of an array
value when arraysize is not "1".
</xs:documentation>
<xs:documentation>
Unless specifically disallowed by the context,
applications should allow optional spaces to
appear in an actual data value before and after
the delimiter (e.g. "1, 5" when delim=",").
</xs:documentation>
<xs:documentation>
the default is " "; i.e. the values are delimited
by spaces.
</xs:documentation>
</xs:annotation>
</xs:attribute>
<xs:attribute name="extendedType" type="xs:string">
<xs:annotation>
<xs:documentation>
The data value represented by this type can be
interpreted as of a custom type identified by
the value of this attribute.
</xs:documentation>
<xs:documentation>
If an application does not recognize this
extendedType, it should attempt to handle value
assuming the type given by the element's value.
string is a recommended default type.
</xs:documentation>
<xs:documentation>
This element may make use of the extendedSchema
attribute and/or any arbitrary (qualified)
attribute to refine the identification of the
type.
</xs:documentation>
</xs:annotation>
</xs:attribute>
<xs:attribute name="extendedSchema" type="xs:anyURI">
<xs:annotation>
<xs:documentation>
An identifier for the schema that the value given
by the extended attribute is drawn from.
</xs:documentation>
<xs:documentation>
This attribute is normally ignored if the
extendedType attribute is not present.
</xs:documentation>
</xs:annotation>
</xs:attribute>
<xs:anyAttribute namespace="##other" />
</xs:extension>
</xs:simpleContent>
</xs:complexType>
<!--
- this definition is taken from the VOTable arrayDEF type
-->
<xs:simpleType name="ArrayShape">
<xs:annotation>
<xs:documentation>
An expression of a the shape of a multi-dimensional array
of the form LxNxM... where each value between gives the
integer length of the array along a dimension. An
asterisk (*) as the last dimension of the shape indicates
that the length of the last axis is variable or
undetermined.
</xs:documentation>
</xs:annotation>
<xs:restriction base="xs:token">
<xs:pattern value="([0-9]+x)*[0-9]*[*]?"/>
</xs:restriction>
</xs:simpleType>
<xs:complexType name="SimpleDataType">
<xs:annotation>
<xs:documentation>
a data type restricted to a small set of names which is
imprecise as to the format of the individual values.
</xs:documentation>
<xs:documentation>
This set is intended for describing simple input parameters to
a service or function.
</xs:documentation>
</xs:annotation>
<xs:simpleContent>
<xs:restriction base="vs:DataType">
<xs:enumeration value="integer"/>
<xs:enumeration value="real"/>
<xs:enumeration value="complex"/>
<xs:enumeration value="boolean"/>
<xs:enumeration value="char"/>
<xs:enumeration value="string"/>
<xs:attribute name="arraysize" type="vs:ArrayShape" default="1"/>
<xs:attribute name="delim" type="xs:string" default=" "/>
<xs:attribute name="extendedType" type="xs:string"/>
<xs:attribute name="extendedSchema" type="xs:anyURI"/>
<xs:anyAttribute namespace="##other" />
</xs:restriction>
</xs:simpleContent>
</xs:complexType>
<xs:complexType name="TableDataType" abstract="true">
<xs:annotation>
<xs:documentation>
an abstract parent for a class of data types that can be
used to specify the data type of a table column.
</xs:documentation>
</xs:annotation>
<xs:simpleContent>
<xs:extension base="vs:DataType"/>
</xs:simpleContent>
</xs:complexType>
<xs:complexType name="VOTableType">
<xs:annotation>
<xs:documentation>
a data type supported explicitly by the VOTable format
</xs:documentation>
</xs:annotation>
<xs:simpleContent>
<xs:restriction base="vs:TableDataType">
<xs:enumeration value="boolean"/>
<xs:enumeration value="bit"/>
<xs:enumeration value="unsignedByte"/>
<xs:enumeration value="short"/>
<xs:enumeration value="int"/>
<xs:enumeration value="long"/>
<xs:enumeration value="char"/>
<xs:enumeration value="unicodeChar"/>
<xs:enumeration value="float"/>
<xs:enumeration value="double"/>
<xs:enumeration value="floatComplex"/>
<xs:enumeration value="doubleComplex"/>
<xs:attribute name="arraysize" type="vs:ArrayShape" default="1"/>
<xs:attribute name="delim" type="xs:string" default=" "/>
<xs:attribute name="extendedType" type="xs:string"/>
<xs:attribute name="extendedSchema" type="xs:anyURI"/>
<xs:anyAttribute namespace="##other" />
</xs:restriction>
</xs:simpleContent>
</xs:complexType>
<xs:complexType name="TAPDataType" abstract="true">
<xs:annotation>
<xs:documentation>
an abstract parent for the specific data types supported
by the Table Access Protocol.
</xs:documentation>
</xs:annotation>
<xs:simpleContent>
<xs:extension base="vs:TableDataType">
<xs:attribute name="size" type="xs:positiveInteger">
<xs:annotation>
<xs:documentation>
the length of the fixed-length value
</xs:documentation>
<xs:documentation>
This corresponds to the size Column attribute in
the TAP_SCHEMA and can be used with data types
that are defined with a length (CHAR, BINARY).
</xs:documentation>
</xs:annotation>
</xs:attribute>
</xs:extension>
</xs:simpleContent>
</xs:complexType>
<xs:complexType name="TAPType">
<xs:annotation>
<xs:documentation>
a data type supported explicitly by the Table Access
Protocol (v1.0).
</xs:documentation>
</xs:annotation>
<xs:simpleContent>
<xs:restriction base="vs:TAPDataType">
<xs:enumeration value="BOOLEAN"/>
<xs:enumeration value="SMALLINT"/>
<xs:enumeration value="INTEGER"/>
<xs:enumeration value="BIGINT"/>
<xs:enumeration value="REAL"/>
<xs:enumeration value="DOUBLE"/>
<xs:enumeration value="TIMESTAMP"/>
<xs:enumeration value="CHAR"/>
<xs:enumeration value="VARCHAR"/>
<xs:enumeration value="BINARY"/>
<xs:enumeration value="VARBINARY"/>
<xs:enumeration value="POINT"/>
<xs:enumeration value="REGION"/>
<xs:enumeration value="CLOB"/>
<xs:enumeration value="BLOB"/>
<xs:attribute name="arraysize" type="vs:ArrayShape" default="1"/>
<xs:attribute name="delim" type="xs:string" default=" "/>
<xs:attribute name="extendedType" type="xs:string"/>
<xs:attribute name="extendedSchema" type="xs:anyURI"/>
<xs:attribute name="size" type="xs:positiveInteger"/>
<xs:anyAttribute namespace="##other" />
</xs:restriction>
</xs:simpleContent>
</xs:complexType>
<xs:complexType name="StandardSTC">
<xs:annotation>
<xs:documentation>
a description of standard space-time coordinate systems,
positions, and regions.
</xs:documentation>
<xs:documentation>
This resource provides a mechanism for registering standard
coordinate systems which other resources may reference as
part of a coverage descripiton. In particular, coverage
descriptions will refer to components of the STC
descriptions in this resource via an IVOA identifier. It
is intended that an application consuming such coverage
descriptions be able to semantically interpret the
identifier without resolving it. For this reason, once a
standard STC description is registered with this resource
type, updating the description is strongly discouraged.
</xs:documentation>
</xs:annotation>
<xs:complexContent>
<xs:extension base="vr:Resource">
<xs:sequence>
<xs:element name="stcDefinitions"
type="stc:stcDescriptionType"
minOccurs="1" maxOccurs="unbounded">
<xs:annotation>
<xs:documentation>
An STC description of coordinate systems,
positions, and/or regions
</xs:documentation>
<xs:documentation>
Each system, position, and region description
should have a an XML ID assigned to it.
</xs:documentation>
<xs:documentation>
Because the STC schema sets
elementFormDefault="qualified", it is
recommended that this element specify the STC
default namespace via an xmlns namespace.
</xs:documentation>
</xs:annotation>
</xs:element>
</xs:sequence>
</xs:extension>
</xs:complexContent>
</xs:complexType>
<xs:complexType name="ForeignKey">
<xs:annotation>
<xs:documentation>
A description of the mapping a foreign key--a set of
columns from one table--to columns in another table.
</xs:documentation>
<xs:documentation>
This definition that the foreign key is being described
within the context of the table containing the key.
</xs:documentation>
</xs:annotation>
<xs:sequence>
<xs:element name="targetTable" type="xs:token">
<xs:annotation>
<xs:documentation>
the fully-qualified name (including catalog and schema, as
applicable) of the table that can be joined with the
table containing this foreign key.
</xs:documentation>
</xs:annotation>
</xs:element>
<xs:element name="fkColumn" type="vs:FKColumn"
minOccurs="1" maxOccurs="unbounded">
<xs:annotation>
<xs:documentation>
a pair of column names, one from this table and one
from the target table that should be used to join the
tables in a query.
</xs:documentation>
</xs:annotation>
</xs:element>
<xs:element name="description" type="xs:token" minOccurs="0">
<xs:annotation>
<xs:documentation>
a free-text description of what this key points to
and what the relationship means.
</xs:documentation>
</xs:annotation>
</xs:element>
<xs:element name="utype" type="xs:token" minOccurs="0">
<xs:annotation>
<xs:documentation>
an identifier for a concept in a data model that
the association enabled by this key represents.
</xs:documentation>
<xs:documentation>
The format defined in the VOTable standard is highly
recommended.
</xs:documentation>
</xs:annotation>
</xs:element>
</xs:sequence>
</xs:complexType>
<xs:complexType name="FKColumn">
<xs:annotation>
<xs:documentation>
A pair of columns that are used to join two tables.
</xs:documentation>
<xs:documentation>
To do an inner join of data from the two tables, a query should
include a constraint that sets the value from the first column equal
to the value in the second column.
</xs:documentation>
<xs:documentation>
This type assumes that it is used in the context of
implied source (i.e., current) and target tables, as in
the ForeignKey type's fkColumn.
</xs:documentation>
</xs:annotation>
<xs:sequence>
<xs:element name="fromColumn" type="xs:token">
<xs:annotation>
<xs:documentation>
The unqualified name of the column from the current table.
</xs:documentation>
</xs:annotation>
</xs:element>
<xs:element name="targetColumn" type="xs:token">
<xs:annotation>
<xs:documentation>
The unqualified name of the column from the target table.
</xs:documentation>
</xs:annotation>
</xs:element>
</xs:sequence>
</xs:complexType>
</xs:schema>
Appendix B: Compatibility Issues with VODataService 1.0
The working draft version 1.0 of the VODataService schema has been in
use in IVOA registries since about 2008. It is expected that
registries will migrate over to version 1.1 gradually and during the
transition, there may well be instances of both v1.1 and v1.0 in the
same registry. While the metadata structures are the mostly the same
(particularly the core VOResource metadata), it is worth enumerating
where they are different as this can affect how queries against
differing metadata are formed.
- In v1.1,
<schema> replaces v1.0's
<catalog>.
- In v1.0, the root element of a table description in a
vs:DataCollection was
<catalog>. Consequently, a
<table> element in a v1.1 record is one
level lower than in v1.0.
- In v1.0, the root element of a table description in a
vs:CatalogService was
<table>. Consequently, a
<table> element in a v1.1 record is one
level lower than in v1.0.
- Version 1.1's
vs:Coverage type now
contains a <regionOfRegard> element. In
v1.0, this metadatum was only available via
coverage/stc:STCResourceProfile/stc:AstroCoord/stc:Size.
- Version 1.1's
vs:TableParam (for describing table
columns) adds <utype> and
<flag> elements. The v1.1
vs:InputParam adds a <utype>
element.
Appendix C: Change History
Changes since PR-20090903:
- added
<:testQuery> to vs:ParamHTTP
- in text, added explanation of
vs:Format
- grammatical clean-up
Changes since WD-20090508 (v1.10):
- corrected errors in example in Introduction
- added
<description> and
<utype> elements to the
vs:ForeignKey type for consistency with TAP.
- changed type names
vs:TAP to
vs:TAPType and vs:VOTable
vs:VOTableType.
- [ADQL]
- Ortiz, I., Lusted, J., Dowler, P., Szalay, A., Shirasaki, Y.,
Nieto-Santisteban, M., Ohishi, M., O'Mullane, W., Osuna, P. 2008,
IVOA Astronomical Data Query Language, v2.00, IVOA
Recommendation,
http://www.ivoa.net/Documents/latest/ADQL.html
- [HTTP]
- Fielding, R., Gettys, J, Mogul, J., Frystyk, H., Masinter, L.,
Leach, P., Berners-Lee, T. 1999.
Hypertext Transfer Protocol -- HTTP/1.1, IETF RFC 2616,
http://www.ietf.org/rfc/rfc2616.txt
- [RFC 2119]
- Bradner, S. 1997.
Key words for use in RFCs to Indicate Requirement
Levels, IETF RFC 2119,
http://www.ietf.org/rfc/rfc2119.txt
- [RM]
- Hanisch, Robert (ed.) 2004.
Resource Metadata for the Virtual Observatory, Version 1.12,
IVOA Recommendation,
http://www.ivoa.net/Documents/REC/ResMetadata/RM-20040426.htm
- [RI]
- Benson, Kevin, Plante, Ray, Auden, Elizabeth, Graham, Matthew, Greene,
Gretchen, Hill, Martin, Linde, Tony, Morris, Dave, O'Mullane,
Wil, Rixon, Guy, Andrews, Kona 2008,
IVOA Registry Interfaces, v1.02, IVOA
Recommendation,
http://www.ivoa.net/Documents/latest/ResourceInterface.html
- [schema]
- Fallside, David C., Walmsley, Priscilla (editors) 2004,
XML Schema
Part 0: Primer Second Edition, W3C Recommendation 28
October 2004,
http://www.w3.org/TR/xmlschema-0/
- [SCS]
- Williams, Roy, Hanisch, Robert, Szalay, Alex and Plante, Ray 2008,
Simple Cone Search Version 1.03, IVOA Recommendation,
http://www.ivoa.net/Documents/REC/DAL/ConeSearch-20080222.html.
- [SIA]
- Tody, Doug, Plante, Ray, and Harrison, Paul 2009,
Simple Image Access Specification Version 1.0, IVOA
Recommendation,
http://www.ivoa.net/Documents/SIA/20091116/.
- [STC]
- Rots, Arnold 2007,
Space-Time Coordinate Metadata for the Virtual Observatory,
v1.33, IVOA Recommendation,
href="http://www.ivoa.net/Documents/REC/STC/STC-20071030.html">
- [SQLGuide]
- Date, C.J. and Darwin, Hugh 1997,
A Guide to the SQL
Standard, Fourth Edition, (Addison-Wesley, Longman Inc.:
Reading), p 24.
- [TAP]
- Dowler, P., Rixon, G., Tody, D. 2010,
Table Access
Protocol, v1.0, IVOA Proposed Recommendation,
http://www.ivoa.net/Documents/TAP/
- [UCD]
- Martinez, A.P., Derriere, S., Delmotte, N., Gray, N., Mann, R.,
McGlynn, T., Ochsenbein, F., Osuna, P., Rixon, G., Williams, R.
2007,
The UCD1+ Controlled Vocabulary,
v1.23, IVOA Recommendation,
http://www.ivoa.net/Documents/latest/UCDlist.html
- [VOR]
- Plante, R., Benson, K., Graham, M., Greene,
G., Harrison, P., Lemson, G., Linde, T., Rixon,
G., Stébé, A. 2008,
VOResource: an XML Encoding Schema for Resource Metadata,
v1.03, IVOA Recommendation,
http://www.ivoa.net/Documents/REC/ReR/VOResource-20080222.html
- [VOSI]
- Graham, M. and Rixon, G. 2010,
IVOA Support Interfaces, v1.00 20101129, IVOA Proposed
Recommendation,
http://www.ivoa.net/Documents/VOSI/20100311/PR-VOSI-1.0-20100311.html
- [VOTable]
- Ochsenbein, F., Williams, R., Davenhall, C., Durand, D.,
Fernique, P., Giaretta, D., Hanisch, R., McGlynn, T., Szalay, A.,
Taylor, M.B., Wicenec, A. 2008,
VOTable Format Definition, version 1.20, IVOA Working Draft,
http://www.ivoa.net/Documents/WD/VOTable/VOTable-20080914.html
- [xml]
- Bray, Tim, Paoli, Jean, Sperberg-McQueen, C. M., Maler, Eve,
Yergeau, Francois (editors) 2004,
Extensible Markup
Language (XML) 1.0 (Third Edition), W3C
Recommendation 04 February 2004,
http://www.w3.org/TR/REC-xml
