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46 <title>IVOA Proposed Recommendation - IVOA Support Interfaces</title>
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54 <body>
55 <div class="head">
56 <a href="http://www.ivoa.net/"><img alt="IVOA" src="http://www.ivoa.net/pub/images/IVOA_wb_300.jpg" width="300" height="169"/></a>
57 <h1>IVOA Support Interfaces<br/>
58 Version 1.00-20101213</h1>
59 <h2>IVOA WG Proposed Recommendation 2010 December 13 </h2>
60
61 <dl>
62 <dt>This version:</dt>
63 <dd><a href="http://www.ivoa.net/Documents/VOSI/20101213/">
64 http://www.ivoa.net/Documents/VOSI/20101213/</a></dd>
65
66 <dt>Latest version:</dt>
67 <dd><a href="http://www.ivoa.net/Documents/latest/VOSI.html">
68 http://www.ivoa.net/Documents/latest/VOSI.html</a></dd>
69
70 <dt>Previous versions:</dt>
71 <dd>PR: <a href="http://www.ivoa.net/Documents/VOSI/20100311/">
72 http://www.ivoa.net/Documents/VOSI/20100311/</a> <br />
73 WD: <a href="http://www.ivoa.net/Documents/VOSI/20090825/">
74 http://www.ivoa.net/Documents/VOSI/20090825/</a> <br />
75 WD: <a href="http://www.ivoa.net/Documents/VOSI/20081030/">
76 http://www.ivoa.net/Documents/VOSI/20081030/</a></dd>
77 </dl>
78
79 <dl>
80 <dt>Working Group:</dt>
81 <dd><a
82 href="http://www.ivoa.net/twiki/bin/view/IVOA/IvoaGridAndWebServices">
83 http://www.ivoa.net/twiki/bin/view/IVOA/IvoaGridAndWebServices</a></dd>
84
85 <dt>Editors:</dt>
86 <dd><a
87 href="http://www.ivoa.net/twiki/bin/view/IVOA/MatthewGraham">Matthew
88 Graham</a><br/>
89 <a
90 href="http://www.ivoa.net/twiki/bin/view/IVOA/GuyRixon">Guy Rixon</a></dd>
91 <dt>Author(s):</dt>
92 <dd>
93 <a
94 href="http://www.ivoa.net/twiki/bin/view/IVOA/IvoaGridAndWebServices">Grid and Web
95 Services Working Group</a><br/>
96 <a href="http://www.ivoa.net/twiki/bin/view/IVOA/"></a>
97 </dd>
98 </dl>
99 <hr/></div>
100
101 <h2><a name="abstract" id="abstract">Abstract</a></h2>
102
103 <p>
104 This document describes the minimum interface that a (SOAP- or REST-based) web service requires to participate in the IVOA.
105 </p>
106
107 <div class="status">
108 <h2><a name="status" id="status">Status of this Document</a></h2>
109
110 <!-- Choose one of the following (and remove the rest)-->
111 <!--Note-->
112 <!--
113 <p>This is an IVOA Note expressing suggestions from and opinions of the authors.<br/>
114 It is intended to share best practices, possible approaches, or other perspectives on interoperability with the Virtual Observatory.
115 It should not be referenced or otherwise interpreted as a standard specification.</p>
116 <p>This is an IVOA Working Draft for review by IVOA members and other interested parties.<br/>
117 It is a draft document and may be updated, replaced, or obsoleted by other documents at any time.
118 It is inappropriate to use IVOA Working Drafts as reference materials -->
119 <!--or to cite them as other than "work in progress.</p>
120 -->
121 <!--Proposed Recommendation-->
122 <p>This is an IVOA Proposed Recommendation made available for public review.<br/>
123 It is appropriate to reference this document only as a recommended standard that is under review and which may be changed
124 before it is accepted as a full recommendation.<br/>
125 The first release of this document was 2010 March 11 .
126 </p>
127 <!--Recommendation
128 <p>This document has been produced by the IVOA "WG Name" Working Group.<br/>
129 It has been reviewed by IVOA Members and other interested parties, and has been endorsed by the IVOA Executive Committee as an IVOA Recommendation.
130 It is a stable document and may be used as reference material or cited as a normative reference from another document. IVOA's role in making the Recommendation is to draw attention to the specification and to promote its widespread deployment.
131 This enhances the functionality and interoperability inside the Astronomical Community.</p>
132 -->
133
134 A list of <a href="http://www.ivoa.net/Documents/">current IVOA Recommendations and other technical documents</a> can be found at http://www.ivoa.net/Documents/.
135
136 </div><br />
137
138 <h2><a name="acknowledgments" id="acknowledgments">Acknowledgments</a></h2>
139 <p>This document has been developed with support from the
140 <a href="http://www.nsf.gov/">National Science Foundation's</a>
141 Information Technology Research Program under Cooperative Agreement
142 AST0122449 with The Johns Hopkins University, from the
143 <a href="http://www.pparc.ac.uk/">UK Particle Physics and Astronomy
144 Research Council (PPARC)</a>, from the European Commission's (EC)
145 <a href="http://cordis.europa.eu/fp6/">Sixth
146 Framework Programme</a> via the <a href="http://www.astro-opticon.org/">
147 Optical Infrared Coordination Network (OPTICON)</a>, and from EC's
148 <a href="http://cordis.europa.eu/fp7/">Seventh Framework Programme</a>
149 via its
150 <a href="http://cordis.europa.eu/fp7/ict/e-infrastructure/home_en.html">
151 eInfrastructure Science Repositories initiative</a>. </p>
152
153 <p>This work is based on discussions and actions from the 2003 IVOA
154 meeting in Strasbourg and further discussions on registry
155 functionality at JHU late in 2003. Later inputs came from a local
156 meeting at JHU in Sept. 2004. William O'Mullane and Ani Thakar were the editors and primary authors for these early versions.</p>
157 <p>
158 The decision to split the interfaces into a mandatory set and optional logging interfaces was taken by GWS-WG at the IVOA meeting of May 2006.
159 </p>
160
161 <h2><a name="conformance" id="conformance">Conformance related definitions</a></h2>
162 <p>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].</p><p>
163 The <strong>Virtual Observatory (VO)</strong> is a general term for a
164 collection of federated resources that can be used to conduct
165 astronomical research, education, and outreach. The <strong>International Virtual Observatory Alliance (IVOA)</strong> is a global collaboration of separately funded projects to develop standards and infrastructure that enable VO applications. The International Virtual Observatory (IVO) application is an application that takes advantage of IVOA standards and infrastructure to provide some VO service.
166 </p>
167
168 <h2><a id="contents" name="contents">Contents</a></h2>
169 <div class="head">
170 <ul class="toc">
171 <li><a href="#abstract">Abstract</a></li>
172 <li><a href="#status">Status</a></li>
173 <li><a href="#acknowledgments">Acknowledgments</a></li>
174 <li><a href="#contents">Contents</a></li>
175 <li><a href="#sec1">1. Introduction</a></li>
176 <ul class="toc"><li><a href="#sec1_1">1.1 The role in the IVOA Architecture</a></li>
177 <li><a href="#sec2">2. Standard VO interfaces</a></li>
178 <ul class="toc">
179 <li><a href="#sec2_1">2.1 Capability metadata</a></li>
180 <li><a href="#sec2_2">2.2 Non-service metadata (non-normative description)</a></li>
181 <li><a href="#sec2_3">2.3 Availability metadata</a></li>
182 <li><a href="#sec2_4">2.4 Table metadata</a></li>
183 <li><a href="#sec2_5">2.5 Registration of VOSI endpoints</a></li>
184 </ul>
185
186 <br/>
187 <li><a href="#appA">Appendix A: VOSI XML schemas</a></li>
188 <li><a href="#appB">Appendix B: Changes from previous versions</a></li>
189 <li><a href="#ref">References</a></li>
190 </ul>
191 </div>
192 <hr/>
193
194
195 <br/>
196 <h2><a name="sec1">1. Introduction</a></h2>
197 <p>The web services that comprise much of the Virtual Observatory (VO)
198 come in two forms: SOAP-based (Simple Object Access Protocol, [1])
199 ones such as footprint and spectrum services [2], SkyNodes and Open
200 SkyQuery [3], registry interfaces [4] and CDS access [5]; and RESTful
201 (REpresentational State Transfer, [6]) ones such as TAP [7] and other
202 second generation data access (DAL) services, and VOSpace 2.0
203 [8]. This document describes a set of common basic functions that all
204 these services should provide in the form of a standard support interface
205 in order to support the effective management of the VO.
206 </p>
207 <p>
208 The IVOA Web Services Basic Profile [9] mandates that a compliant
209 SOAP-based web service should have the interface defined in this
210 specification, as expressed using the standard WSDL (Web Services
211 Description Language, [10]) format. For RESTful services, the
212 requirement for the support interface is stated in the specification for each kind of service. A contract for a RESTful service may specify extra constraints (e.g., on the form of the URIs) for the support interface. </p>
213
214
215 <h3><a name="sec1_2">1.2 The role in the IVOA Architecture</a></h3>
216 <p>The IVOA Architecture [11] provides a high-level view of how IVOA
217 standards work together to connect users and applications with
218 providers of data and services, as depicted in the diagram in Fig. 1.
219 </p>
220
221 <p>
222 <center>
223 <font size="-1">
224 <img src="vosi-in-arch.png" width="756"/> <br />
225 <blockquote>
226 <strong>Figure 1. VOSI in the IVOA Architecture.</strong>
227 VOSI is the standard that defines the basic functions that all VO
228 services should provide in order to support management of the VO.
229 </blockquote>
230 </font>
231 </center>
232 </p>
233
234 <p>In this architecture, users employ a variety of tools (from the
235 User Layer) to discover and access archives and services of interest
236 (represented in the Resource Layer). VOSI ensures that all of these
237 services have a common interface that describes the capabilities of
238 the resource (which IVOA standard function is being supported, such as a SSAP + SSLDM
239 service) and how to invoke this service, including records of any
240 details of the implementation or the functions that are not fixed in
241 the standard for that function. VOSI also defines the various possible
242 states of this service, such as available, up since, down at, back
243 at, etc. This allows for interoperable code to manage all VO services.
244 </p>
245
246
247 <h2><a name="sec2">2. Interface bindings</a></h2>
248 <p>The standard interface returns metadata without changing the
249 state of the service with which it is associated. This could, in principle, be
250 implemented in any of three ways:</p>
251 <ol type="1">
252 <li> As extra SOAP operations on an existing SOAP endpoint of the
253 service with which it is associated. This would be a 'SOAP binding' of VOSI.
254 <li> As SOAP operations on a separate SOAP endpoint. This would be an alternate form of the SOAP binding.
255 <li> As web resources with distinct URLs, without using the SOAP protocol. This is the 'REST binding' for the standard interface.
256 </ol><p>
257 This standard requires the REST binding of VOSI even when applied to
258 services that otherwise use SOAP. No details of the SOAP binding are
259 given in this version of the standard. </p>
260 <p>
261 In the REST binding, the support interfaces shall have distinct URLs
262 in the HTTP scheme and shall be accessible by the GET operation in the
263 HTTP protocol. The response to an HTTP POST, PUT or DELETE to these
264 resources is not defined by this specification. However, if an
265 implementation has no special action to perform for these requests,
266 the normal response would be a HTTP 405 "Method not allowed" status code. </p><p>
267 The endpoints and interface types for the support interface shall be
268 defined in the service's registration using one <i>Capability</i> element for
269 each interface. The values of the <i>standardID</i> attribute for these <i>Capability</i>s are given in section 4.</p><p>
270 When using the REST binding, any HTTP URLs may be used. The client
271 must find the appropriate URLs from the service's entry in the VO registry and, in general, should not try and infer the URLs from any other URLs for that service. However, standards for specific services may put extra constraints on the form of the URLs.</p>
272 </p>
273
274
275 <h2><a name="sec3">3. Metadata specification</a></h2>
276 <p>
277 There are various classes of metadata that might be returned by a
278 service through its standard interface:</p>
279 <ul>
280 <li> those describing its functional capabilities
281 <li> those describing its operational behaviour - availability,
282 reliability, etc.
283 <li> those describing tabular data handled by the service
284 <li> those describing other aspects of the service
285 </ul>
286 <p>This section defines how each of these classes is represented. The
287 following typographic convention is used to represent a XML element defined
288 within a particular namespace:</p>
289 <pre>
290 {http://some.name.space}elementName
291 </pre>
292 <p>For example,
293 <i>{http://www.ivoa.net/xml/VOResource/v1.0}resource</i> indicates a
294 XML element named <i>resource</i> that is described in the XML schema
295 associated with the 'http://www.ivoa.net/xml/VOResource/v1.0'
296 namespace - in this case, this would be VOResource.xsd [12].
297 </p>
298
299 <h3><a name="sec3_1">3.1 Capability metadata</a></h3>
300
301 <p></p
302 <blockquote>
303 <table bgcolor="#dddddd" border="2" cellpadding="5"><tbody><tr><td>
304 <dl style="margin-top: 0pt; margin-bottom: 0pt">
305 <dt> <strong>Note:</strong> </dt>
306 <dd>'Capability' is unfortunately an overloaded term in the VO
307 referring to both a functional aspect of a service
308 and also particular pieces of metadata defined by various XML
309 schema. When referring to an XML element called 'capability', it
310 shall be be put in italics. Its parent namespace may also be
311 included (using the syntax described above) if it is ambiguous
312 which XML schema is being referred to.
313 </dd>
314 </dl>
315 </td></tr></tbody></table>
316 </blockquote>
317 <p></p>
318
319 <p>This interface provides the service metadata in the form of a list
320 of <i>Capability</i> descriptions. Each of these descriptions is an XML element that: </p>
321 <ul>
322 <li> states that the service provides a particular, IVOA-standard function;
323 <li> lists the interfaces for invoking that function;
324 <li> records any details of the implementation of the function that
325 are not defined as default or constant in the standard for that function.
326 </ul>
327 <p>
328 For example, one capability might describe a cone search function and
329 another the TAP implementation but these two might well apply to the same service.</p><p>
330 An entry for a service in the resource registry - i.e., its VOResource
331 - contains the Dublin Core resource metadata (identifier, curation
332 information, content description, etc.) followed by the service's
333 capability descriptions (expressed as a series of
334 <i>{http://www.ivoa.net/xml/VOResource/v1.0}Capability</i> elements). Effectively, the resource metadata describes the service to human users and the capability list describes it to software. Therefore, the latter list has two uses:</p>
335 <ul><li>it may be read by a client application to find out how to invoke the service. This presumes that the service has been already been selected and the VOSI endpoint located.
336 <li>it may be read by the registry itself to compile the registry entry for the service. In this case, the resource metadata are entered into the registry directly and the service metadata are then read from the service. Since the service implementation usually knows its capabilities, this removes the need for a human to type them into the registry.
337 </ul></p>
338
339 <p>
340 The service metadata shall be represented as an XML document with the
341 root element
342 <i>{http://www.ivoa.net/xml/VOSICapabilities/v1.0}capabilities</i>.
343 (See <a href="#appA1">Appendix A.1</a> for the definition of the
344 VOSICapabilities XML schema.) This element must contain one or more child
345 <i>capability</i> elements that describe the capabilities of the
346 service. Given that the <i>capability</i> element is defined to be of type
347 <i>{http://www.ivoa.net/xml/VOResource/v1.0}Capability</i>, a <i>capability</i>
348 element may be represented by a legal sub-type of
349 <i>{http://www.ivoa.net/xml/VOResource/v1.0}Capability</i>, in which
350 case, the <i>capability</i> element must use an <i>xsi:type</i>
351 attribute to identify the sub-type (see section 2.2.1 of
352 [<a href="#ref:vor">1</a>]).
353 </p>
354
355 <p></p
356 <blockquote>
357 <table bgcolor="#dddddd" border="2" cellpadding="5"><tbody><tr><td>
358 <dl style="margin-top: 0pt; margin-bottom: 0pt">
359 <dt> <strong>Note:</strong> </dt>
360 <dd> The value of the <i>capability</i> element's standardID attribute is used
361 to indicate the service's support for particular standard protocols
362 (such as Simple Image Access, Simple Cone Search, etc.). In the
363 case of some protocols, the support for the standard is further
364 characterized by additional metadata provided by a standard XML
365 schema extension of <i>Capability</i> for that protocol. The extension metadata is enabled by
366 adding a <i>xsi:type</i> attribute to the <i>capability</i> element set to the
367 <i>Capability</i> sub-type value defined in the extension schema for that protocol (see example below). </dd>
368 </dl>
369 </td></tr></tbody></table>
370 </blockquote>
371 <p></p>
372
373 <p>
374 The VOResource list of capabilities should include capabilities describing VOSI
375 endpoints as specified in section 4.
376 </p>
377
378
379 <p>
380 In the REST binding, the service metadata shall be a single web
381 resource with a registered URL. The date and time at which the
382 metadata last changed shall be obtained from the <i>Last-Modified</i>
383 HTTP Header keyword sent in the response to a GET or HEAD request to the registered URI.</p><p>
384 All VO services should provide this interface.
385 </p>
386
387 <h3><a name="sec3_2">3.2 Non-service metadata (non-normative)</a></h3>
388 <p>There may be other metadata associated with a service than the capability metadata described above.
389 <ul><li> Every service has the Dublin Core resource metadata [13].
390 <li> Some services are associated with registered applications.
391 <li> Some services are associated with registered data collections.
392 </ul></p><p>None of these are explicitly provided for in this version of VOSI. Some might be covered in later versions of VOSI.
393 </p>
394
395 <h3><a name="sec3_3">3.3 Availability metadata</a></h3>
396 <p>This interface indicates whether the service is operable and the reliability of the service for extended and scheduled requests.
397 The availability shall be represented as an XML document in which the
398 root element is <i>{http://www.ivoa.net/xml/Availability/v1.0}availability</i>. This element
399 shall contain child elements providing the following information.</p>
400 <ul>
401 <li> <i>available</i> - whether the service is currently accepting requests
402 <li> <i>upSince</i> - duration for which the service has been continuously available
403 <li> <i>downAt</i> - the instant at which the service is next scheduled to be unavailable
404 <li> <i>backAt</i> - the instant at which the service is scheduled to become available again after down time;
405 <li> <i>note</i> - textual note, e.g. explaining the reason for unavailaility.
406 </ul><p>
407 The elements <i>upSince</i>, <i>downAt</i>, <i>backAt</i> and <i>note</i> are optional. The <i>available</i> element is mandatory. There may be more than one <i>note</i> element.</p><p>
408 The XML document shall conform to the schema given in appendix A.2 of this specification.</p><p>
409 When reporting availability, the service should do a good check on its underlying parts to see if it is still operational and not just make a simple return from a web server, e.g., if it relies on a database it should check that the database is still up. If any of these checks fail, the service should set <i>available</i> to false in the availability output.</p><p>
410 If a service is to be online but unavailable for work (e.g., when a service with a work queue intends to shut down after draining the queue) then the service should set <i>available</i> to false.</p><p>
411 There are no special elements in the availability document for the
412 contact details of the service operator. These details may be given as
413 a <i>note</i> element if they are known to the service.</p>
414 <p>
415 In the REST binding, the availability shall be a single web resource with a registered URL</p><p>
416 All VO services shall provide this interface.
417 </p>
418
419 <h3><a name="sec3_4">3.4 Table metadata</a></h3>
420 <p>
421 Some services deal with tabular data. These data may be the target of
422 ADQL queries, as in TAP [14], or they may be the output of other operations, as in SIAP queries. In each case, it is useful if the service describes the details of the tables concerned. It is more useful if this description can be captured in the resource registry.</p><p>
423 The <i>VODataService</i> standard [<a href="#ref:vos">2</a>] defines XML elements for describing a set of tables. These elements can be included in a resource document for a service.</p><p>
424 A service which uses tables in its interface should define a VOSI
425 endpoint from which table metadata can be read. The table metadata
426 shall be represented as an XML document of which the root element is
427 of type
428 <i>{http://www.ivoa.net/xml/VODataService/v1.1}TableSet</i>. This
429 element may contain any mix of elements allowed by the VODataService
430 XML schema.</p><p>
431 In the REST binding, the table metadata shall be a single web resource with a registered URL.
432 </p>
433
434 <h2><a name="sec4">4. Registration of VOSI endpoints</a></h2>
435 <p>
436 The endpoints for the service and availability metadata shall be
437 included in the registration of each service that provides them.
438 </p>
439 <center>
440 <table>
441 <tr><th align="left">Endpoint type</th><th align="left">standardID value</th></tr>
442 <tr><td>availability</td><td>ivo://ivoa.net/std/VOSI#availability</td></tr>
443 <tr><td>capabilties</td><td>ivo://ivoa.net/std/VOSI#capabilities</td></tr>
444 <tr><td>tables</td><td>ivo://ivoa.net/std/VOSI#tables</td></tr>
445 </table>
446 </center>
447 <p>
448 An availability endpoint shall be represented by an element named
449 <i>capability</i>, of type
450 <i>{http://www.ivoa.net/xml/VOResource/v1.0}Capability</i> (defined by
451 the standard VOResource XML schema [<a href="ref:vor">1</a>]). The
452 value of the <i>standardID</i> attribute of the <i>capability</i>
453 shall be <i>ivo://ivoa.net/std/VOSI#availability</i>.
454 </p>
455
456 <p>
457 A capabilities endpoint should be represented by an element named
458 <i>capability</i>, of type
459 <i>{http://www.ivoa.net/xml/VOResource/v1.0}Capability</i>. If such
460 a <i>capability</i> is provided then the value of the <i>standardID</i> attribute must be <i>ivo://ivoa.net/std/VOSI#capabilities.</i></p><p>
461 A tables endpoint should be represented by an element named
462 <i>capability</i>, of type
463 <i>{http://www.ivoa.net/xml/VOResource/v1.0}Capability</i>. If such
464 a <i>capability</i> is provided then the value of the <i>standardID</i> attribute must be <i>ivo://ivoa.net/std/VOSI#tables</i>.
465 </p>
466
467 <p>
468 With all three VOSI functions, the capability element that describes
469 the function must contain an interface element of a type semantically
470 appropriate for the binding of the function to the service; the
471 <i>accessURL</i> element within the interface element indicates the
472 endpoint for the VOSI function. For the REST binding, this
473 <i>accessURL</i> element must set the <i>use</i> attribute to "full".
474 Furthermore, for the REST binding, this document recommends using the
475 <i>{http://www.ivoa.net/xml/VODataService/v1.1}ParamHTTP</i> interface
476 type to encode VOSI endpoints (see example given in section 2.1).
477 </p>
478
479
480 <h2><a name="sec5">5. Example VOSI responses</a></h2>
481
482 <!-- Space to push page break in PDF version
483 <br />
484 <br />
485 -->
486
487 <div class="exampleOuter">
488 <a name="ex:caps">
489 </a><div class="exampleHeader">Example 1:</div>
490 <div class="exampleWrapper">A sample response from a capabilities
491 resource describing an SIA service. </div>
492 <div class="exampleInner" style="background-color: rgb(213, 222, 227);">
493 <pre>&lt;?xml version="1.0" encoding="UTF-8"?&gt;
494 &lt;vosi:capabilities xmlns:vosi="http://www.ivoa.net/xml/VOSICapabilities/v1.0"
495 xmlns:vr="http://www.ivoa.net/xml/VOResource/v1.0"
496 xmlns:vs="http://www.ivoa.net/xml/VODataService/v1.0"
497 xmlns:sia="http://www.ivoa.net/xml/SIA/v1.0"
498 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
499 xsi:schemaLocation="http://www.ivoa.net/xml/VOSI/v1.0
500 http://www.ivoa.net/xml/VOSI/v1.0
501 http://www.ivoa.net/xml/VOResource/v1.0
502 http://www.ivoa.net/xml/VOResource/v1.0
503 http://www.ivoa.net/xml/VODataService/v1.0
504 http://www.ivoa.net/xml/VODataService/v1.0
505 http://www.ivoa.net/xml/SIA/v1.0
506 http://www.ivoa.net/xml/SIA/v1.0"&gt;
507
508 &lt;!-- a generic capability (for custom, non-standard interfaces) --&gt;
509 &lt;capability&gt;
510 &lt;interface xsi:type="vr:WebBrowser"&gt;
511 &lt;accessURL use="full"&gt; http://adil.ncsa.uiuc.edu/siaform.html &lt;/accessURL&gt;
512 &lt;/interface&gt;
513 &lt;/capability&gt;
514
515 &lt;!-- the SIA capability --&gt;
516 &lt;capability xsi:type="sia:SimpleImageAccess" standardID="ivo://ivoa.net/std/SIA"&gt;
517 &lt;interface xsi:type="vs:ParamHTTP" role="std"&gt;
518 &lt;accessURL&gt; http://adil.ncsa.uiuc.edu/cgi-bin/voimquery?survey=f&amp;amp; &lt;/accessURL&gt;
519 &lt;/interface&gt;
520
521 &lt;imageServiceType&gt;Pointed&lt;/imageServiceType&gt;
522 &lt;maxQueryRegionSize&gt;
523 &lt;long&gt;360.0&lt;/long&gt;
524 &lt;lat&gt;180.0&lt;/lat&gt;
525 &lt;/maxQueryRegionSize&gt;
526 &lt;maxImageExtent&gt;
527 &lt;long&gt;360.0&lt;/long&gt;
528 &lt;lat&gt;180.0&lt;/lat&gt;
529 &lt;/maxImageExtent&gt;
530 &lt;maxImageSize&gt;
531 &lt;long&gt;5000&lt;/long&gt;
532 &lt;lat&gt;5000&lt;/lat&gt;
533 &lt;/maxImageSize&gt;
534 &lt;maxFileSize&gt;100000000&lt;/maxFileSize&gt;
535 &lt;maxRecords&gt;5000&lt;/maxRecords&gt;
536 &lt;/capability&gt;
537
538 &lt;!-- the interface that returns this document --&gt;
539 &lt;capability standardID="ivo://ivoa.net/std/VOSI#capabilities"&gt;
540 &lt;interface xsi:type="vs:ParamHTTP" role="std"&gt;
541 &lt;accessURL use="full"&gt; http://adil.ncsa.uiuc.edu/cgi-bin/voimquery/capabilities &lt;/accessURL&gt;
542 &lt;/interface&gt;
543 &lt;/capability&gt;
544
545 &lt;!-- the interface that returns this document --&gt;
546 &lt;capability standardID="ivo://ivoa.net/std/VOSI#availability"&gt;
547 &lt;interface xsi:type="vs:ParamHTTP" role="std"&gt;
548 &lt;accessURL use="full"&gt; http://adil.ncsa.uiuc.edu/cgi-bin/voimquery/availability &lt;/accessURL&gt;
549 &lt;/interface&gt;
550 &lt;/capability&gt;
551 &lt;/vosi:capabilities&gt;
552 </pre>
553 </div></div>
554 <br/>
555 <div class="exampleOuter">
556 <a name="ex:caps">
557 </a><div class="exampleHeader">Example 2:</div>
558 <div class="exampleWrapper">A sample response from a tables
559 resource describing a TAP service. </div>
560 <div class="exampleInner" style="background-color: rgb(213, 222, 227);">
561 <pre>
562 &lt;?xml version="1.0" encoding="UTF-8"?>
563 &lt;vosi:tableset
564 xmlns:vosi="http://www.ivoa.net/xml/VOSITables/v1.0"
565 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
566 xmlns:vod="http://www.ivoa.net/xml/VODataService/v1.1">
567 &lt;schema>
568 &lt;name>cfht &lt;/name>
569 &lt;table type="output">
570 &lt;name>cfht.deepU &lt;/name>
571 &lt;column>
572 &lt;name>cfhtlsID &lt;/name>
573 &lt;dataType xsi:type="vod:TAP" size="30">adql:VARCHAR &lt;/dataType>
574 &lt;/column>
575 &lt;column>
576 &lt;name>survey &lt;/name>
577 &lt;dataType xsi:type="vod:TAP" size="6">adql:VARCHAR &lt;/dataType>
578 &lt;/column>
579 &lt;column>
580 &lt;name>field &lt;/name>
581 &lt;dataType xsi:type="vod:TAP" size="2">adql:VARCHAR &lt;/dataType>
582 &lt;/column>
583 &lt;column>
584 &lt;name>pointing &lt;/name>
585 &lt;dataType xsi:type="vod:TAP" size="6">adql:VARCHAR &lt;/dataType>
586 &lt;/column>
587 &lt;column>
588 &lt;name>selectionFilter &lt;/name>
589 &lt;dataType xsi:type="vod:TAP" size="2">adql:VARCHAR &lt;/dataType>
590 &lt;/column>
591 &lt;/table>
592 &lt;table type="output">
593 &lt;name>TAP_SCHEMA.keys &lt;/name>
594 &lt;column>
595 &lt;name>key_id &lt;/name>
596 &lt;description>unique key to join to TAP_SCHEMA.key_columns &lt;/description>
597 &lt;dataType xsi:type="vod:TAP" size="64">adql:VARCHAR &lt;/dataType>
598 &lt;/column>
599 &lt;column>
600 &lt;name>from_table &lt;/name>
601 &lt;description>the table with the foreign key &lt;/description>
602 &lt;dataType xsi:type="vod:TAP" size="64">adql:VARCHAR &lt;/dataType>
603 &lt;/column>
604 &lt;column>
605 &lt;name>target_table &lt;/name>
606 &lt;description>the table with the primary key &lt;/description>
607 &lt;dataType xsi:type="vod:TAP" size="64">adql:VARCHAR &lt;/dataType>
608 &lt;/column>
609 &lt;/table>
610 &lt;/schema>
611 &lt;/vosi:tableset>
612 </pre>
613 </div></div>
614
615
616 <br/>
617 <h2><a name="appA">Appendix A: VOSI XML schemas</a></h2>
618
619 <a name="appA1">
620 <h3>A.1. The Complete VOSICapabilities Schema</h3></a>
621
622 <pre>&lt;xsd:schema targetNamespace="http://www.ivoa.net/xml/VOSICapabilities/v1.0"
623 xmlns:tns="http://www.ivoa.net/xml/VOSICapabilities/v1.0"
624 xmlns:vr="http://www.ivoa.net/xml/VOResource/v1.0"
625 xmlns:xsd="http://www.w3.org/2001/XMLSchema"
626 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
627 elementFormDefault="qualified"
628 attributeFormDefault="unqualified"
629 version="1.0rc1"&gt;
630
631 &lt;xsd:annotation&gt;
632 &lt;xsd:documentation&gt;
633 A schema for formatting service capabilities as returned by a
634 capabilities resource, defined by the IVOA Support Interfaces
635 specification (VOSI).
636 See http://www.ivoa.net/Documents/latest/VOSI.html.
637 &lt;/xsd:documentation&gt;
638 &lt;/xsd:annotation&gt;
639
640 &lt;xsd:import namespace="http://www.ivoa.net/xml/VOResource/v1.0"
641 schemaLocation="http://www.ivoa.net/xml/VOResource/v1.0" /&gt;
642
643 &lt;!--
644 - the root element for a VOSI capabilities metadata (section 2.1)
645 --&gt;
646 &lt;xsd:element name="capabilities"&gt;
647 &lt;xsd:annotation&gt;
648 &lt;xsd:documentation&gt;
649 A listing of capabilities supported by a service
650 &lt;/xsd:documentation&gt;
651 &lt;/xsd:annotation&gt;
652
653 &lt;xsd:complexType&gt;
654 &lt;xsd:sequence&gt;
655
656 &lt;xsd:element name="capability" type="vr:Capability"
657 form="unqualified" minOccurs="0" maxOccurs="unbounded"&gt;
658 &lt;xsd:annotation&gt;
659 &lt;xsd:documentation&gt;
660 A capability supported by the service.
661 &lt;/xsd:documentation&gt;
662 &lt;xsd:documentation&gt;
663 A protocol-specific capability is included by specifying a
664 vr:Capability sub-type via an xsi:type attribute on this
665 element.
666 &lt;/xsd:documentation&gt;
667 &lt;/xsd:annotation&gt;
668 &lt;/xsd:element&gt;
669
670 &lt;/xsd:sequence&gt;
671 &lt;/xsd:complexType&gt;
672 &lt;/xsd:element&gt;
673
674 &lt;/xsd:schema&gt;
675 </pre>
676
677 <a name="appA2">
678 <h3>A.2. The Complete VOSIAvailability Schema</h3></a>
679
680 <pre>&lt;xsd:schema targetNamespace="http://www.ivoa.net/xml/VOSIAvailability/v1.0"
681 xmlns:tns="http://www.ivoa.net/xml/VOSIAvailability/v1.0"
682 xmlns:vr="http://www.ivoa.net/xml/VOResource/v1.0"
683 xmlns:xsd="http://www.w3.org/2001/XMLSchema"
684 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
685 elementFormDefault="qualified"
686 attributeFormDefault="unqualified"
687 version="1.0rc1"&gt;
688
689 &lt;xsd:annotation&gt;
690 &lt;xsd:documentation&gt;
691 A schema for formatting availability metadata as returned by an
692 availability resource defined in the IVOA Support Interfaces
693 specification (VOSI).
694 See http://www.ivoa.net/Documents/latest/VOSI.html.
695 &lt;/xsd:documentation&gt;
696 &lt;/xsd:annotation&gt;
697
698 &lt;!--
699 - the root element for a VOSI availability (section 2.3)
700 --&gt;
701 &lt;xsd:element name="availability" type="tns:Availability"/&gt;
702
703 &lt;xsd:complexType name="Availability"&gt;
704 &lt;xsd:sequence&gt;
705
706 &lt;xsd:element name="available" type="xsd:boolean"&gt;
707 &lt;xsd:annotation&gt;
708 &lt;xsd:documentation&gt;
709 Indicates whether the service is currently available.
710 &lt;/xsd:documentation&gt;
711 &lt;/xsd:annotation&gt;
712 &lt;/xsd:element&gt;
713
714 &lt;xsd:element name="upSince" type="xsd:dateTime" minOccurs="0"&gt;
715 &lt;xsd:annotation&gt;
716 &lt;xsd:documentation&gt;
717 The instant at which the service last became available.
718 &lt;/xsd:documentation&gt;
719 &lt;/xsd:annotation&gt;
720 &lt;/xsd:element&gt;
721
722 &lt;xsd:element name="downAt" type="xsd:dateTime" minOccurs="0"&gt;
723 &lt;xsd:annotation&gt;
724 &lt;xsd:documentation&gt;
725 The instant at which the service is next scheduled to become
726 unavailable.
727 &lt;/xsd:documentation&gt;
728 &lt;/xsd:annotation&gt;
729 &lt;/xsd:element&gt;
730
731 &lt;xsd:element name="backAt" type="xsd:dateTime" minOccurs="0"&gt;
732 &lt;xsd:annotation&gt;
733 &lt;xsd:documentation&gt;
734 The instant at which the service is scheduled to become available
735 again after a period of unavailability.
736 &lt;/xsd:documentation&gt;
737 &lt;/xsd:annotation&gt;
738 &lt;/xsd:element&gt;
739
740 &lt;xsd:element name="note" type="xsd:string"
741 minOccurs="0" maxOccurs="unbounded"&gt;
742 &lt;xsd:annotation&gt;
743 &lt;xsd:documentation&gt;
744 A textual note concerning availability.
745 &lt;/xsd:documentation&gt;
746 &lt;/xsd:annotation&gt;
747 &lt;/xsd:element&gt;
748
749 &lt;/xsd:sequence&gt;
750 &lt;/xsd:complexType&gt;
751
752 &lt;/xsd:schema&gt;
753 </pre>
754
755 <a name="appA3">
756 <h3>A.3. The Complete VOSITables Schema</h3></a>
757
758 <br/>
759 <h2><a name="appB">Applendix B: Changes from previous versions</a></h2>
760
761 <h4>Changes since PR-20100311</h4>
762 <ul>
763 <li>Inclusion of IVOA Architecture text </li>
764 <li>Restructuring and clarification in response to RFC comments</li>
765 <li>Inclusion of VOSITables schema in appendix</li>
766 <li>Second example added for a TAP service response</li>
767 </ul>
768
769 <h4>Changes since WD-20090825</h4>
770
771 <ul>
772 <li> Mandate the use of VOSICapabilities to return capabilities </li>
773 <li> S2.1: added non-normative note about capability sub-types; added
774 example capabilities metadata </li>
775 <li> Recommend the inclusion of VOSI interfaces in capability metadata</li>
776 <li> S2.5: When returning capabilities metadata, require VOSI (REST)
777 accessURLs to have use="full"; recommend this use of ParamHTTP. </li>
778 <li> Rename Availability schema to VOSIAvailability; added
779 VOSICapabilities schema. </li>
780 </ul>
781
782 <h4>Changes since WD-20081030</h4>
783
784 <p>The REST binding is made mandatory for all kinds of service. Details of the SOAP binding, including its WSDL contract, are removed.</p><p>
785 The definition of the root element for the table-metadata document is corrected. Instead of requiring the <i>tableset</i> element from <i>VODataService 1.1</i> (which element does not exist in that schema), the text now requires an element of type <i>TableSet</i>.
786 </p>
787
788 <br/>
789 <h2><a name="ref">References</a></h2>
790
791 <dl>
792 <dt> <a name="ref:vor">[1]</a> </dt>
793 <dd> Plante, R., Benson, K., Graham, M., Greene,
794 G., Harrison, P., Lemson, G., Linde, T., Rixon,
795 G., St&eacute;b&eacute;, A. 2008, <cite>
796 <a href="http://www.ivoa.net/Documents/cover/VOResource-20080222.html">
797 VOResource: an XML Encoding Schema for Resource Metadata</a></cite>,
798 v1.03, IVOA Recommendation,
799 <code>http://www.ivoa.net/Documents/cover/VOResource-20080222.html</code>
800 </dd>
801
802 <dt> <a name="ref:vos">[2]</a> </dt>
803 <dd> Plante, R., St&eacute;b&eacute;, A., Benson, K., Dowler, P.,
804 Graham, M., Greene, G., Harrison, P., Lemson, G., Linde, T.,
805 Rixon, G. 2008, <cite>
806 <a href="http://www.ivoa.net/Documents/VODataService/20090903/">
807 VODataService: a VOResource Schema Extension for Describing
808 Collections and Services</a></cite>,
809 v1.1, IVOA Proposed Recommendation,
810 <code>http://www.ivoa.net/Documents/VODataService/20090903/</code>
811 </dd>
812 </dl>
813
814
815
816 </body></html>

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