- From: Jonathan Marsh via cvs-syncmail <cvsmail@w3.org>
- Date: Wed, 03 Aug 2005 23:38:26 +0000
- To: public-ws-desc-eds@w3.org
Update of /sources/public/2002/ws/desc/wsdl20
In directory hutz:/tmp/cvs-serv21569
Modified Files:
altschemalangs.html
Log Message:
Index: altschemalangs.html
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RCS file: /sources/public/2002/ws/desc/wsdl20/altschemalangs.html,v
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! <link rel="stylesheet" type="text/css" href=
! "http://www.w3.org/StyleSheets/TR/base.css" />
! <link rel="contents" href="#contents" />
! </head>
! <body>
! <div class="head">
! <h1>Discussion of Alternative Schema Languages and Type System
! Support in WSDL</h1>
! <h2 id="h2-title"></h2>
! <dl>
! <dt id="dt-this-version">This version:</dt>
! <dd><a href=
! "http://www.w3.org/TR/2004/WD-wsdl20-20040803">http://www.w3.org/TR/2005/@@</a></dd>
! <dt>Latest version:</dt>
! <dt>Previous versions:</dt>
! <dt>Editors:</dt>
! <dd>Amy Lewis, TIBCO</dd>
! <dd>Bijan Parsia, Maryland Information and Network Dynamics
! Laboratory at the University of Maryland at College Park</dd>
! </dl>
! <p class="copyright"><a href=
! "http://www.w3.org/Consortium/Legal/ipr-notice#Copyright">Copyright</a> © <a href="http://www.w3.org/"><acronym title="World Wide Web Consortium">W3C</acronym></a><sup>®</sup>
! (<a href="http://www.csail.mit.edu/"><acronym title=
! "Massachusetts Institute of Technology">MIT</acronym></a>, <a href=
! "http://www.ercim.org/"><acronym title=
! "European Research Consortium for Informatics and Mathematics">ERCIM</acronym></a>,
! <a href="http://www.keio.ac.jp/">Keio</a>), All Rights Reserved.
! W3C <a href=
! "http://www.w3.org/Consortium/Legal/ipr-notice#Legal_Disclaimer">liability</a>,
! <a href=
! "http://www.w3.org/Consortium/Legal/ipr-notice#W3C_Trademarks">trademark</a>
! and <a href=
! "http://www.w3.org/Consortium/Legal/copyright-documents">document
! use</a> rules apply.</p>
! </div>
! <hr />
! <div>
! <h2><a name="abstract" id="abstract">Abstract</a></h2>
! </div>
! <div>
! <h2><a name="status" id="status">Status of this Document</a></h2>
! <p><strong>This document is an editors' copy that has no official
! standing.</strong></p>
! <p><em>This section describes the status of this document at the
! time of its publication. Other documents may supersede this
! document. A list of current W3C publications and the latest
! revision of this technical report can be found in the <a href=
! "http://www.w3.org/TR/">W3C technical reports index</a> at
! http://www.w3.org/TR/.</em></p>
! </div>
! <hr />
! <div class="toc">
! <h2><a name="shortcontents" id="shortcontents">Short Table of
! Contents</a></h2>
! <p class="toc">1. <a href="#intro">Introduction</a><br />
! 2. <a href="#multipleschemalangs">Issues facing multiple schema
! languages/type systems</a><br />
! 3. <a href="#examples">Examples of Specifications of Extension
! Elements for Alternative Schema Language Support.</a><br /></p>
! </div>
! <hr />
! <div class="toc">
! <h2><a name="contents" id="contents">Table of Contents</a></h2>
! <p class="toc">1. <a href="#intro">Introduction</a><br />
! 2. <a href="#multipleschemalangs">Issues facing multiple schema
! languages/type systems</a><br />
! 3. <a href="#examples">Examples of Specifications of Extension
! Elements for Alternative Schema Language Support.</a><br />
! 3.1 <a href="#dtd">DTD</a><br />
! 3.1.1 <a href=
! "#dtd-namespaceaii">namespace attribute information item</a><br />
! 3.1.2 <a href=
! "#dtd-locationaii">location attribute information item</a><br />
! 3.1.3 <a href=
! "#dtd-ref">References to Element Definitions</a><br />
! 3.2 <a href="#relax">RELAX NG</a><br />
! 3.2.1 <a href=
! "#import-relax">Importing RELAX NG</a><br />
! 3.2.1.1
! <a href="#relax-import-nsaii">ns attribute information
! item</a><br />
! 3.2.1.2
! <a href="#relax-import-hrefaii">href attribute information
! item</a><br />
! 3.2.2 <a href=
! "#relax-embed">Embedding RELAX NG</a><br />
! 3.2.2.1
! <a href="#relax-embed-nsaii">ns attribute information
! item</a><br />
! 3.2.3 <a href=
! "#relax-ref">References to Element Declarations</a><br /></p>
! </div>
! <hr />
! <div class="body">
! <div class="div1">
! <h2><a name="intro" id="intro"></a>1. Introduction</h2>
! <p>WSDL describes Web Service interaction in terms of exchanges of
! typed messages. WSDL 2.0: Part 1 only provides general support for
! type systems based on the XML infoset [<a href=
! "http://dev.w3.org/cvsweb/~checkout~/2002/ws/desc/wsdl20/wsdl20.html?content-type=text/html;%20charset=utf-8#XMLInfoSet">XML
! Information Set</a>.]. and specific support for the W3C XML Schema
! Description Language. Describing messages with WSDL using schema
! languages other than XML Schema or non-XML infoset type systems
! requires extending the WSDL component model. While the WSDL working
! group has not defined any such extensions, there were discussions
! in the working group about how those extensions might be defined
! and used. This document is the result of those disucussions and
! captures part of the working group's thinking about schema language
! and type system extensibilty at the time of its publication.</p>
! </div>
! <div class="div1">
! <h2><a name="multipleschemalangs" id="multipleschemalangs"></a>2.
! Issues facing multiple schema languages/type systems</h2>
! <p>Without the use of an extension, a WSDL document can only use a
! single type system, XML Schema. If extensions are defined to
! support alternative schema languages or non-XML type systems, then
! issues regarding the <em>mixing</em> of type systems in a single
! document arise. Part 1 does <em>not</em> define the behavior of
! mixed type system documents, so it is incumbent on extension
! authors to do so.</p>
! <p>For example, suppose a WSDL author used a extension supporting
! Relax NG along side the native support for XML Schema. Further
! suppose that there is an element component which has a definition
! in both the referenced XML Schema and Relax NG schema. There are
! several possibilities for interpreting such a document:</p>
! <ul>
! <li>
! <p>Multiple definitions in distinct type systems is always an
! error</p>
! </li>
! <li>
! <p>Multiple definitions must be in some sense equivalent, for
! example, if XML Schema type and an Relax NG production validate
! exactly the same set of Infoset fragments, otherwise, an error</p>
! </li>
! <li>
! <p>Multiple definitions are legal, and are interpreted as a union
! type constraint</p>
! </li>
! </ul>
! <p>The last interpretation suggests a further general possibility:
! being able to define a union type (or other compound type) that
! spans distinct type systems (and, to further generalize, where the
! unioned types had distinct QName identifiers). The <a href=
! "http://www.w3.org/2001/sw/DataAccess/">Data Access Working
! Group</a> had a use case wherein their return message could either
! be in <a href=
! "http://www.w3.org/TR/rdf-syntax-grammar/">RDF/XML</a>, which
! cannot have an interesting XML Schema but does have an interesting
! Relax NG schema, and their <a href=
! "http://www.w3.org/TR/rdf-sparql-XMLres/">other results format</a>,
! which they would prefer to specify with an XML Schema. This example
! is little artificial, as the Data Access Working Group could easily
! describe the entire results format in Relax NG.</p>
! <p>The first interpretation is most in the spirit of WSDL and was
! strongly preferred by the working group. Since WSDL extensibility
! points are generally quite unrestricted, the group did not try to
! enforce the first option, but the general belief of the group was
! that the other options were confusing and unwise.</p>
! </div>
! <div class="div1">
! <h2><a name="examples" id="examples"></a>3. Examples of
! Specifications of Extension Elements for Alternative Schema
! Language Support.</h2>
! <div class="div2">
! <h3><a name="dtd" id="dtd"></a>3.1 DTD</h3>
! <p>A DTD may be used as the schema language for WSDL. It may not be
! embedded; it must be imported. A namespace must be assigned. DTD
! types appear in the {element declarations} property of <specref
! ref="Definitions_details"/> and may be referenced from the
! <code>wsdl:input</code> , <code>wsdl:output</code> and
! <code>wsdl:fault</code> elements using the <code>element</code>
! <em>attribute information item</em>.</p>
! <p>The prefix, dtd, used throughout the following is mapped to the
! namespace URI "http://www.example.org/dtd/".</p>
! <p>The <code>dtd:import</code> <em>element information item</em>
! references an external Document Type Definition, and has the
! following infoset properties:</p>
! <ul>
! <li>
! <p>A [local name] of import.</p>
! </li>
! <li>
! <p>A [namespace name] of "http://www.example.org/dtd".</p>
! </li>
! <li>
! <p>One or two <em>attribute information item</em>s, as follows:</p>
! <ul>
! <li>
! <p>A REQUIRED <code>namespace</code> <em>attribute information
! item</em> as described below.</p>
! </li>
! <li>
! <p>An OPTIONAL <code>location</code> <em>attribute information
! item</em> as described below.</p>
! </li>
! </ul>
! </li>
! </ul>
! <div class="div3">
! <h4><a name="dtd-namespaceaii" id="dtd-namespaceaii"></a>3.1.1
! <code>namespace</code> <em>attribute information item</em></h4>
! <p>The <code>namespace</code> <em>attribute information item</em>
! sets the namespace to be used with all imported element definitions
! described in the DTD. It has the following infoset properties:</p>
! <ul>
! <li>
! <p>A [local name] of namespace.</p>
! </li>
! <li>
! <p>A [namespace name] which has no value.</p>
! </li>
! </ul>
! <p>The type of the <code>namespace</code> <em>attribute information
! item</em> is <em>xs:anyURI</em>.</p>
! <p>The WSDL author should ensure that a prefix is associated with
! the namespace at the proper scope (probably document scope).</p>
! </div>
! <div class="div3">
! <h4><a name="dtd-locationaii" id="dtd-locationaii"></a>3.1.2
! <code>location</code> <em>attribute information item</em></h4>
! <p>The <code>location</code> <em>attribute information item</em>,
! if present, provides a hint to the processor as to where the DTD
! may be located. Caching and cataloging technologies may provide
! better information than this hint. The <code>location</code>
! <em>attribute information item</em> has the following infoset
! properties:</p>
! <ul>
! <li>
! <p>A [local name] of location.</p>
! </li>
! <li>
! <p>A [namespace name] which has no value.</p>
! </li>
! </ul>
! <p>The type of the <code>location</code> <em>attribute information
! item</em> is <em>xs:anyURI</em>.</p>
! </div>
! <div class="div3">
! <h4><a name="dtd-ref" id="dtd-ref"></a>3.1.3 References to Element
! Definitions</h4>
! <p>The <code>element</code> <em>attribute information item</em>
! MUST be used when referring to an element definition
! (<!ELEMENT>) from a Message Reference component; referring to
! an element definition from a Interface Fault component is similar.
! The value of the element definition MUST correspond to the content
! of the <code>namespace</code> <em>attribute information item</em>
! of the <code>dtd:import</code> <em>element information item</em>.
! The local name part must correspond to an element defined in the
! DTD.</p>
! <p>Note that this pattern does not attempt to make DTDs
! namespace-aware. It applies namespaces externally, in the import
! phase.</p>
! </div>
! </div>
! <div class="div2">
! <h3><a name="relax" id="relax"></a>3.2 RELAX NG</h3>
! <p>A RELAX NG schema may be used as the schema language for WSDL.
! It may be embedded or imported; import is preferred. A namespace
! must be specified; if an imported schema specifies one, then the
! [actual value] of the <code>namespace</code> <em>attribute
! information item</em> in the <code>import</code> <em>element
! information item</em> must match the specified namespace. RELAX NG
! provides both type definitions and element declarations, the latter
! appears in the {element declarations} property of <specref
! ref="Definitions_details"/> respectively. The following
! discussion supplies the prefix rng which is mapped to the URI
! "http://www.relaxng.org/ns/structure/1.0".</p>
! <div class="div3">
! <h4><a name="import-relax" id="import-relax"></a>3.2.1 Importing
! RELAX NG</h4>
! <p>Importing a RELAX NG schema uses the rng:include mechanism
! defined by RNG, with restrictions on its syntax and semantics. A
! child <em>element information item</em> of the <code>types</code>
! <em>element information item</em> is defined with the Infoset
! properties as follows:</p>
! <ul>
! <li>
! <p>A [local name] of include.</p>
! </li>
! <li>
! <p>A [namespace name] of
! "http://www.relaxng.org/ns/structure/1.0".</p>
! </li>
! <li>
! <p>Two <em>attribute information item</em>s as follows:</p>
! <ul>
! <li>
! <p>A REQUIRED <code>ns</code> <em>attribute information item</em>
! as described below.</p>
! </li>
! <li>
! <p>An OPTIONAL <code>href</code> <em>attribute information
! item</em> as described below.</p>
! </li>
! <li>
! <p>Additional <em>attribute information item</em>s as defined by
! the RNG specification.</p>
! </li>
! </ul>
! </li>
! </ul>
! <p>Note that WSDL restricts the <code>rng:include</code>
! <em>element information item</em> to be empty. That is, it cannot
! redefine <code>rng:start</code> and <code>rng:define</code>
! <em>element information item</em>s; it may be used solely to import
! a schema.</p>
! <div class="div4">
! <h5><a name="relax-import-nsaii" id=
! "relax-import-nsaii"></a>3.2.1.1 <code>ns</code> <em>attribute
! information item</em></h5>
! <p>The <code>ns</code> <em>attribute information item</em> defines
! the namespace of the type and element definitions imported from the
! referenced schema. If the referenced schema contains an
! <code>ns</code> <em>attribute information item</em> on its
! <code>grammar</code> <em>element information item</em>, then the
! values of these two <em>attribute information item</em>s must be
! identical. If the imported grammar does not have an <code>ns</code>
! <em>attribute information item</em> then the namespace specified
! here is applied to all components of the schema as if it did
! contain such an <em>attribute information item</em>. The
! <code>ns</code> <em>attribute information item</em> contains the
! following Infoset properties:</p>
! <ul>
! <li>
! <p>A [local name] of ns.</p>
! </li>
! <li>
! <p>A [namespace name] which has no value.</p>
! </li>
! </ul>
! <p>The type of the <code>ns</code> <em>attribute information
! item</em> is <em>xs:anyURI</em>.</p>
! </div>
! <div class="div4">
! <h5><a name="relax-import-hrefaii" id=
! "relax-import-hrefaii"></a>3.2.1.2 <code>href</code> <em>attribute
! information item</em></h5>
! <p>The <code>href</code> <em>attribute information item</em> must
! be present, according to the rules of the RNG specification.
! However, WSDL allows it to be empty, and considers it only a hint.
! Caching and cataloging technologies may provide better information
! that this hint. The <code>href</code> <em>attribute information
! item</em> has the following Infoset properties:</p>
! <ul>
! <li>
! <p>A [local name] of href.</p>
! </li>
! <li>
! <p>A [namespace name] which has no value.</p>
! </li>
! </ul>
! <p>The type of the <code>href</code> <em>attribute information
! item</em> is <em>xs:anyURI</em>.</p>
! </div>
! </div>
! <div class="div3">
! <h4><a name="relax-embed" id="relax-embed"></a>3.2.2 Embedding
! RELAX NG</h4>
! <p>Embedding an RNG schema uses the existing top-level
! <code>rng:grammar</code> <em>element information item</em>. It may
! be viewed as simply cutting and pasting an existing, stand-alone
! schema to a location inside the <code>wsdl:types</code> <em>element
! information item</em>. The <code>rng:grammar</code> <em>element
! information item</em> has the following Infoset properties:</p>
! <ul>
! <li>
! <p>A [local name] of grammar.</p>
! </li>
! <li>
! <p>A [namespace name] of
! "http://www.relaxng.org/ns/structure/1.0".</p>
! </li>
! <li>
! <p>A REQUIRED <code>ns</code> <em>attribute information item</em>s
! as described below.</p>
! </li>
! <li>
! <p>Additional <em>attribute information item</em>s as specified for
! the <code>rng:grammar</code> <em>element information item</em> in
! the RNG specification.</p>
! </li>
! <li>
! <p>Child <em>element information item</em>s as specified for the
! <code>rng:grammar</code> <em>element information item</em> in the
! RNG specification.</p>
! </li>
! </ul>
! <div class="div4">
! <h5><a name="relax-embed-nsaii" id="relax-embed-nsaii"></a>3.2.2.1
! <code>ns</code> <em>attribute information item</em></h5>
! <p>The <code>ns</code> <em>attribute information item</em> defines
! the namespace of the type and element definitions embedded in this
! schema. WSDL modifies the RNG definition of the
! <code>rng:grammar</code> <em>element information item</em> to make
! this <em>attribute information item</em> required. The
! <code>ns</code> <em>attribute information item</em> has the
! following infoset properties:</p>
! <ul>
! <li>
! <p>A [local name] of ns.</p>
! </li>
! <li>
! <p>A [namespace name] which has no value.</p>
! </li>
! </ul>
! <p>The type of the <code>ns</code> <em>attribute information
! item</em> is <em>xs:anyURI</em>.</p>
! </div>
! </div>
! <div class="div3">
! <h4><a name="relax-ref" id="relax-ref"></a>3.2.3 References to
! Element Declarations</h4>
! <p>Whether embedded or imported, the element definitions present in
! a schema may be referenced from a Message Reference or Interface
! Fault component.</p>
! <p>A named rng:define definition MUST NOT be referenced from the
! Message Reference or Interface Fault components.</p>
! <p>A named Relax NG element declaration MAY be referenced from a
! Message Reference or Interface Fault component. The QName is
! constructed from the namespace (<code>ns</code> <em>attribute
! information item</em>) of the schema and the content of the
! <code>name</code> <em>attribute information item</em> of the
! <code>element</code> <em>element information item</em> An
! <code>element</code> <em>attribute information item</em> MUST NOT
! be used to refer to an <code>rng:define</code> <em>element
! information item</em>.</p>
! </div>
! </div>
! </div>
! </div>
! </body>
! </html>
--- 46,510 ----
div.exampleHeader { font-weight: bold;
margin: 4px}
! </style><link rel="stylesheet" type="text/css" href="http://www.w3.org/StyleSheets/TR/base.css"><link rel="contents" href="#contents"></head><body>
! <div class="head">
! <h1>Discussion of Alternative Schema Languages and Type System Support in WSDL</h1>
! <h2 id="h2-title"> </h2><dl><dt id="dt-this-version">This version:</dt><dd>
! <a href="http://www.w3.org/TR/2004/WD-wsdl20-20040803">http://www.w3.org/TR/2005/@@</a>
! </dd><dt>Latest version:</dt><dd>
!
! </dd><dt>Previous versions:</dt><dd>
!
! </dd><dt>Editors:</dt>
! <dd>Amy Lewis, TIBCO</dd>
! <dd>Bijan Parsia, Maryland Information and Network Dynamics Laboratory at the University
! of Maryland at College Park</dd>
! </dl><p class="copyright"><a href="http://www.w3.org/Consortium/Legal/ipr-notice#Copyright">Copyright</a> © <a href="http://www.w3.org/"><acronym title="World Wide Web Consortium">W3C</acronym></a><sup>®</sup> (<a href="http://www.csail.mit.edu/"><acronym title="Massachusetts Institute of Technology">MIT</acronym></a>, <a href="http://www.ercim.org/"><acronym title="European Research Consortium for Informatics and Mathematics">ERCIM</acronym></a>, <a href="http://www.keio.ac.jp/">Keio</a>), All Rights Reserved. W3C <a href="http://www.w3.org/Consortium/Legal/ipr-notice#Legal_Disclaimer">liability</a>, <a href="http://www.w3.org/Consortium/Legal/ipr-notice#W3C_Trademarks">trademark</a> and <a href="http://www.w3.org/Consortium/Legal/copyright-documents">document use</a> rules apply.</p></div><hr><div>
! <h2><a name="abstract">Abstract</a></h2>
! <p>This document captures the result of disucussions by the Web Services Description Working Group regarding WSDL 2.0 type system extensibilty at the time of its publication. The Working Group normatively defines the use of XML Schema 1.0 as a type system in the WSDL 2.0 Core specification. This document sketches out the basics of extensions for Document Type Definitions (DTDs) and Relax NG.</p>
! </div><div>
! <h2><a name="status">Status of this Document</a></h2><p><strong>This document is an editors' copy that has
! no official standing.</strong></p>
! <p>
! <em>This section describes the status of this document at the time of its
! publication. Other documents may supersede this document. A list of current W3C
! publications and the latest revision of this technical report can be found in
! the <a href="http://www.w3.org/TR/">W3C technical reports index</a> at
! http://www.w3.org/TR/.</em>
! </p>
! <p>
! This document is a <a href="http://www.w3.org/2004/02/Process-20040205/tr.html#q74">W3C
! Working Group Note</a>. It has been produced by the
! <a href="http://www.w3.org/2002/ws/desc/">Web Services
! Description Working Group</a>,
! which is part of the <a href="http://www.w3.org/2002/ws/Activity">Web Services Activity</a>.</p>
! <p>The material in this note was previously
! published as an Appendix of the <a href="http://www.w3.org/TR/2005/WD-wsdl20-20050510">Web Services Description Language (WSDL) 2.0: Core Language Last Call</a>
! specification. In response to Last Call comments, the Working Group agreed to remove this material from that specification and publish it separately as a Working Group Note. Current versions of <a href="http://www.w3.org/TR/wsdl20">WSDL 2.0 Core</a> no longer contain this material. This publication differs from the previous material in that it also includes some expanded discussion of issues that should be given consideration by type system extension designers.</p>
! <p>No further work on this topic is planned at this point. Errors
! in this document can be reported to the public <a href="mailto:public-ws-desc-comments@w3.org">public-ws-desc-comments@w3.org</a>
! mailing list (<a href="http://lists.w3.org/Archives/Public/public-ws-desc-comments/">public
! archive</a>).
! </p>
!
! <p>Publication as a Working Group Note does not imply endorsement
! by the W3C Membership. This is a draft document and may be
! updated, replaced or obsoleted by other documents at any time. It
! is inappropriate to cite this document as other than work in
! progress.</p>
! </div>
! <hr><div class="toc">
! <h2><a name="shortcontents">Short Table of Contents</a></h2><p class="toc">1. <a href="#intro">Introduction</a><br>2. <a href="#multipleschemalangs">Issues facing multiple schema languages/type systems</a><br>3. <a href="#examples">Examples of Specifications of Extension Elements for Alternative Schema Language
! Support.</a><br>A. <a href="#References">References</a><br></p></div><hr><div class="toc">
! <h2><a name="contents">Table of Contents</a></h2><p class="toc">1. <a href="#intro">Introduction</a><br>2. <a href="#multipleschemalangs">Issues facing multiple schema languages/type systems</a><br>3. <a href="#examples">Examples of Specifications of Extension Elements for Alternative Schema Language
! Support.</a><br> 3.1 <a href="#dtd">DTD</a><br> 3.1.1 <a href="#dtd-namespaceaii">
! namespace
! attribute information item
! </a><br> 3.1.2 <a href="#dtd-locationaii">
! location
! attribute information item
! </a><br> 3.1.3 <a href="#dtd-ref">References to Element Definitions</a><br> 3.2 <a href="#relax">RELAX NG</a><br> 3.2.1 <a href="#import-relax">Importing RELAX NG</a><br> 3.2.1.1 <a href="#relax-import-nsaii">
! ns
! attribute information item
! </a><br> 3.2.1.2 <a href="#relax-import-hrefaii">
! href
! attribute information item
! </a><br> 3.2.2 <a href="#relax-embed">Embedding RELAX NG</a><br> 3.2.2.1 <a href="#relax-embed-nsaii">
! ns
! attribute information item
! </a><br> 3.2.3 <a href="#relax-ref">References to Element Declarations</a><br></p>
! <h3><a name="appendix" id="appendix">Appendix</a></h3><p class="toc">A. <a href="#References">References</a><br></p></div><hr><div class="body">
! <div class="div1">
!
! <h2><a name="intro"></a>1. Introduction</h2>
! <p>WSDL 2.0: Core Language [<cite><a href="#WSDL">WSDL 2.0 Core</a></cite>] describes Web Service interaction in terms of exchanges of typed messages. WSDL
! only provides general support for type systems based on the XML Infoset
! [<a href="http://www.w3.org/TR/wsdl20#XMLInfoset">XML Information Set</a>] and specific support for the W3C XML Schema
! Description Language [<cite><a href="#XMLSchemaP1">XML Schema: Structures</a></cite>].
! Describing messages with WSDL using schema languages other
! than XML Schema or non-XML Infoset type systems requires extending the WSDL
! component model. While the Web Services Description Working Group has not
! defined any such extensions,
! there were discussions in the Working Group about how those extensions might be
! defined and used. This document is the result of those disucussions and captures
! part of the Working Group's thinking about schema language and type system
! extensibilty at the time of its publication.</p>
! </div>
! <div class="div1">
!
! <h2><a name="multipleschemalangs"></a>2. Issues facing multiple schema languages/type systems</h2>
! <p>Without the use of an extension, a WSDL document can only use a single
! type system, XML Schema. If extensions are defined to support
! alternative schema languages or non-XML type systems, then issues
! regarding the <em>mixing</em> of type systems in a single document arise. Part
! 1 does <em>not</em> define the behavior of mixed type system documents, so it
! is incumbent on extension authors to do so.</p>
! <p>For example, suppose a WSDL author used a extension supporting Relax NG
! along side the native support for XML Schema. Further suppose that
! there is an element component which has a definition in both the
! referenced XML Schema and Relax NG schema. There are several
! possibilities for interpreting such a document:</p>
! <ul>
! <li>
! <p>Multiple definitions in distinct type systems is always an error</p>
! </li>
! <li>
! <p>Multiple definitions must be in some sense equivalent, for example,
! if XML Schema type and an Relax NG production validate exactly the same
! set of Infoset fragments, otherwise, an error</p>
! </li>
! <li>
! <p>Multiple definitions are legal, and are interpreted as a union type
! constraint</p>
! </li>
! </ul>
! <p>The last interpretation suggests a further general possibility: being
! able to define a union type (or other compound type) that spans
! distinct type systems (and, to further generalize, where the unioned types had
! distinct QName identifiers). The <a href="http://www.w3.org/2001/sw/DataAccess/">Data Access Working Group</a>
! had a use case wherein their return message could either be in
! <a href="http://www.w3.org/TR/rdf-syntax-grammar/">RDF/XML</a>, which
! cannot have an interesting XML Schema but does have an interesting
! Relax NG schema, and their <a href="http://www.w3.org/TR/rdf-sparql-XMLres/">other results format</a>, which they
! would prefer to
! specify with an XML Schema. This example is little artificial, as the
! Data Access Working Group could easily describe the entire results
! format in Relax NG.</p>
! <p>The first interpretation is most in the spirit of WSDL and was strongly
! preferred by the Working Group. Since WSDL extensibility points are generally
! quite unrestricted, the Working Group did not try to enforce the first option, but
! the general belief of the Working Group was that the other options were confusing
! and unwise.</p>
! </div>
! <div class="div1">
!
! <h2><a name="examples"></a>3. Examples of Specifications of Extension Elements for Alternative Schema Language
! Support.</h2>
! <div class="div2">
!
! <h3><a name="dtd"></a>3.1 DTD</h3>
! <p>A Document Type Definition (DTD) as defined in [<cite><a href="#XML10">XML 1.0</a></cite>] may be used as the schema language for WSDL. It may not be embedded; it
! must be imported. A namespace must be assigned. DTD types appear in the {element
! declarations} property of the Description Component and may be
! referenced from the <code>wsdl:input</code> , <code>wsdl:output</code> and
! <code>wsdl:fault</code> elements using the <code>element</code>
! <em>attribute information item</em>.</p>
! <p> The prefix, dtd, used throughout the following is mapped to the namespace URI
! "http://www.example.org/dtd/".</p>
! <p> The <code>dtd:import</code>
! <em>element information item</em> references an external Document Type
! Definition, and has the following Infoset properties:</p>
! <ul>
! <li>
! <p>A [local name] of import.</p>
! </li>
! <li>
! <p>A [namespace name] of "http://www.example.org/dtd".</p>
! </li>
! <li>
! <p>One or two <em>attribute information item</em>s, as follows:</p>
! <ul>
! <li>
! <p>A REQUIRED <code>namespace</code>
! <em>attribute information item</em> as described below.</p>
! </li>
! <li>
! <p>An OPTIONAL <code>location</code>
! <em>attribute information item</em> as described below.</p>
! </li>
! </ul>
! </li>
! </ul>
! <div class="div3">
!
! <h4><a name="dtd-namespaceaii"></a>3.1.1
! <code>namespace</code>
! <em>attribute information item</em>
! </h4>
! <p>The <code>namespace</code>
! <em>attribute information item</em> sets the namespace to be used with
! all imported element definitions described in the DTD. It has the following
! Infoset properties:</p>
! <ul>
! <li>
! <p>A [local name] of namespace.</p>
! </li>
! <li>
! <p>A [namespace name] which has no value.</p>
! </li>
! </ul>
! <p>The type of the <code>namespace</code>
! <em>attribute information item</em> is <em>xs:anyURI</em>.</p>
! <p>The WSDL author should ensure that a prefix is associated with the namespace
! at the proper scope (probably document scope).</p>
! </div>
! <div class="div3">
!
! <h4><a name="dtd-locationaii"></a>3.1.2
! <code>location</code>
! <em>attribute information item</em>
! </h4>
! <p>The <code>location</code>
! <em>attribute information item</em>, if present, provides a hint to the
! processor as to where the DTD may be located. Caching and cataloging
! technologies may provide better information than this hint. The
! <code>location</code>
! <em>attribute information item</em> has the following Infoset
! properties:</p>
! <ul>
! <li>
! <p>A [local name] of location.</p>
! </li>
! <li>
! <p>A [namespace name] which has no value.</p>
! </li>
! </ul>
! <p>The type of the <code>location</code>
! <em>attribute information item</em> is <em>xs:anyURI</em>.</p>
! </div>
! <div class="div3">
!
! <h4><a name="dtd-ref"></a>3.1.3 References to Element Definitions</h4>
! <p> The <code>element</code>
! <em>attribute information item</em> MUST be used when referring to an
! element definition (<!ELEMENT>) from a Message Reference
! component; referring to an element definition from a Interface Fault
! component is similar. The value of the element definition MUST correspond to
! the content of the <code>namespace</code>
! <em>attribute information item</em> of the <code>dtd:import</code>
! <em>element information item</em>. The local name part must correspond
! to an element defined in the DTD. </p>
! <p> Note that this pattern does not attempt to make DTDs namespace-aware. It
! applies namespaces externally, in the import phase.</p>
! </div>
! </div>
! <div class="div2">
!
! <h3><a name="relax"></a>3.2 RELAX NG</h3>
! <p>A RELAX NG [<cite><a href="#RelaxNG">Relax NG</a></cite>] schema may be used as the schema language for WSDL. It may be embedded
! or imported; import is preferred. A namespace must be specified; if an imported
! schema specifies one, then the [actual value] of the <code>namespace</code>
! <em>attribute information item</em> in the <code>import</code>
! <em>element information item</em> must match the specified namespace. RELAX
! NG provides both type definitions and element declarations, the latter appears
! in the {element declarations} property of Description Component
! respectively. The following discussion supplies the prefix rng which is mapped
! to the URI "http://www.relaxng.org/ns/structure/1.0".</p>
! <div class="div3">
!
! <h4><a name="import-relax"></a>3.2.1 Importing RELAX NG</h4>
! <p> Importing a RELAX NG schema uses the rng:include mechanism defined by RNG,
! with restrictions on its syntax and semantics. A child <em>element
! information item</em> of the <code>types</code>
! <em>element information item</em> is defined with the Infoset properties
! as follows:</p>
! <ul>
! <li>
! <p>A [local name] of include.</p>
! </li>
! <li>
! <p>A [namespace name] of "http://www.relaxng.org/ns/structure/1.0".</p>
! </li>
! <li>
! <p>Two <em>attribute information item</em>s as follows:</p>
! <ul>
! <li>
! <p>A REQUIRED <code>ns</code>
! <em>attribute information item</em> as described
! below.</p>
! </li>
! <li>
! <p>An OPTIONAL <code>href</code>
! <em>attribute information item</em> as described
! below.</p>
! </li>
! <li>
! <p>Additional <em>attribute information item</em>s as
! defined by the RNG specification.</p>
! </li>
! </ul>
! </li>
! </ul>
! <p> Note that WSDL restricts the <code>rng:include</code>
! <em>element information item</em> to be empty. That is, it cannot
! redefine <code>rng:start</code> and <code>rng:define</code>
! <em>element information item</em>s; it may be used solely to import a
! schema.</p>
! <div class="div4">
!
! <h5><a name="relax-import-nsaii"></a>3.2.1.1
! <code>ns</code>
! <em>attribute information item</em>
! </h5>
! <p>The <code>ns</code>
! <em>attribute information item</em> defines the namespace of the
! type and element definitions imported from the referenced schema. If the
! referenced schema contains an <code>ns</code>
! <em>attribute information item</em> on its <code>grammar</code>
! <em>element information item</em>, then the values of these two
! <em>attribute information item</em>s must be identical. If the
! imported grammar does not have an <code>ns</code>
! <em>attribute information item</em> then the namespace specified
! here is applied to all components of the schema as if it did contain
! such an <em>attribute information item</em>. The <code>ns</code>
! <em>attribute information item</em> contains the following Infoset
! properties:</p>
! <ul>
! <li>
! <p>A [local name] of ns.</p>
! </li>
! <li>
! <p>A [namespace name] which has no value.</p>
! </li>
! </ul>
! <p>The type of the <code>ns</code>
! <em>attribute information item</em> is <em>xs:anyURI</em>.</p>
! </div>
! <div class="div4">
!
! <h5><a name="relax-import-hrefaii"></a>3.2.1.2
! <code>href</code>
! <em>attribute information item</em>
! </h5>
! <p> The <code>href</code>
! <em>attribute information item</em> must be present, according to
! the rules of the RNG specification. However, WSDL allows it to be empty,
! and considers it only a hint. Caching and cataloging technologies may
! provide better information that this hint. The <code>href</code>
! <em>attribute information item</em> has the following Infoset
! properties:</p>
! <ul>
! <li>
! <p>A [local name] of href.</p>
! </li>
! <li>
! <p>A [namespace name] which has no value.</p>
! </li>
! </ul>
! <p>The type of the <code>href</code>
! <em>attribute information item</em> is <em>xs:anyURI</em>.</p>
! </div>
! </div>
! <div class="div3">
!
! <h4><a name="relax-embed"></a>3.2.2 Embedding RELAX NG</h4>
! <p> Embedding an RNG schema uses the existing top-level <code>rng:grammar</code>
! <em>element information item</em>. It may be viewed as simply cutting
! and pasting an existing, stand-alone schema to a location inside the
! <code>wsdl:types</code>
! <em>element information item</em>. The <code>rng:grammar</code>
! <em>element information item</em> has the following Infoset properties:</p>
! <ul>
! <li>
! <p>A [local name] of grammar.</p>
! </li>
! <li>
! <p>A [namespace name] of "http://www.relaxng.org/ns/structure/1.0".</p>
! </li>
! <li>
! <p>A REQUIRED <code>ns</code>
! <em>attribute information item</em>s as described below.</p>
! </li>
! <li>
! <p>Additional <em>attribute information item</em>s as specified for
! the <code>rng:grammar</code>
! <em>element information item</em> in the RNG specification.</p>
! </li>
! <li>
! <p>Child <em>element information item</em>s as specified for the
! <code>rng:grammar</code>
! <em>element information item</em> in the RNG specification.</p>
! </li>
! </ul>
! <div class="div4">
!
! <h5><a name="relax-embed-nsaii"></a>3.2.2.1
! <code>ns</code>
! <em>attribute information item</em>
! </h5>
! <p> The <code>ns</code>
! <em>attribute information item</em> defines the namespace of the
! type and element definitions embedded in this schema. WSDL modifies the
! RNG definition of the <code>rng:grammar</code>
! <em>element information item</em> to make this <em>attribute
! information item</em> required. The <code>ns</code>
! <em>attribute information item</em> has the following Infoset
! properties:</p>
! <ul>
! <li>
! <p>A [local name] of ns.</p>
! </li>
! <li>
! <p>A [namespace name] which has no value.</p>
! </li>
! </ul>
! <p>The type of the <code>ns</code>
! <em>attribute information item</em> is <em>xs:anyURI</em>.</p>
! </div>
! </div>
! <div class="div3">
!
! <h4><a name="relax-ref"></a>3.2.3 References to Element Declarations</h4>
! <p>Whether embedded or imported, the element definitions present in a schema may
! be referenced from a Message Reference or Interface Fault component.</p>
! <p> A named rng:define definition MUST NOT be referenced from the Message
! Reference or Interface Fault components. </p>
! <p> A named Relax NG element declaration MAY be referenced from a Message
! Reference or Interface Fault component. The QName is constructed from the
! namespace (<code>ns</code>
! <em>attribute information item</em>) of the schema and the content of
! the <code>name</code>
! <em>attribute information item</em> of the <code>element</code>
! <em>element information item</em> An <code>element</code>
! <em>attribute information item</em> MUST NOT be used to refer to an
! <code>rng:define</code>
! <em>element information item</em>. </p>
! </div>
! </div>
! </div>
! </div>
! <div class="back">
! <div class="div1">
!
! <h2><a name="References"></a>A. References</h2>
!
! <dl>
! <dt class="label"><a name="RelaxNG"></a>[Relax NG] </dt><dd>
! <cite><a href="http://www.relaxng.org/spec-20011203.html">RELAX NG Specification</a></cite>, James Clark, MURATA Makoto, editors. OASIS Committee Specification, 3 December 2001.</dd>
!
! <dt class="label"><a name="WSDL"></a>[WSDL 2.0 Core] </dt><dd>
! <cite><a href="http://www.w3.org/TR/2005/WD-wsdl20-20050803">Web Services Description Language (WSDL) Version 2.0 Part 1: Core Language</a></cite>, R. Chinnici, J-J.
! Moreau, A. Ryman, S. Weerawarana, Editors. World Wide Web Consortium,
! 3 Aug 2005. This version of
! the "Web Services Description Language (WSDL) Version 2.0 Part 1: Core Language" Specification is available is available at
! http://www.w3.org/TR/2005/WD-wsdl20-20050803. The <a href="http://www.w3.org/TR/wsdl20">latest version of
! "Web Services Description Language (WSDL) Version 2.0 Part 1: Core Language"</a> is available at http://www.w3.org/TR/wsdl20. </dd>
!
! <dt class="label"><a name="XML10"></a>[XML 1.0] </dt><dd>
! <cite><a href="http://www.w3.org/TR/2004/REC-xml-20040204/">Extensible Markup Language (XML) 1.0 (Third
! Edition)</a></cite>, T. Bray, J. Paoli,
! C. M. Sperberg-McQueen, E. Maler, and F. Yergeau, Editors. World Wide
! Web Consortium, 4 February 2004. This version of the XML 1.0 Recommendation is
! http://www.w3.org/TR/2004/REC-xml-20040204/. The <a href="http://www.w3.org/TR/REC-xml">latest version of "Extensible Markup Language (XML) 1.0"</a> is available at http://www.w3.org/TR/REC-xml.
! </dd>
! <dt class="label"><a name="XMLInfoSet"></a>[XML Information Set] </dt><dd>
! <cite><a href="http://www.w3.org/TR/2001/REC-xml-infoset-20011024">XML Information Set</a></cite>, J. Cowan and R.
! Tobin, Editors. World Wide Web Consortium, 24 October 2001.
! This version of the XML Information Set Recommendation is
! http://www.w3.org/TR/2001/REC-xml-infoset-20011024. The <a href="http://www.w3.org/TR/xml-infoset">latest version of
! XML Information Set</a> is available at
! http://www.w3.org/TR/xml-infoset.
! </dd>
!
! <dt class="label"><a name="XMLSchemaP1"></a>[XML Schema: Structures] </dt><dd>
! <cite><a href="http://www.w3.org/TR/2004/REC-xmlschema-1-20041028/">XML Schema Part 1: Structures</a></cite>,
! H. Thompson, D. Beech, M. Maloney, and N. Mendelsohn,
! Editors. World Wide Web Consortium, 28 October 2004. This version
! of the XML Schema Part 1 Recommendation is
! http://www.w3.org/TR/2004/REC-xmlschema-1-20041028. The <a href="http://www.w3.org/TR/xmlschema-1/">latest version of
! XML Schema Part 1</a> is available at
! http://www.w3.org/TR/xmlschema-1.
! </dd>
! </dl>
! </div>
! </div>
! </body></html>
\ No newline at end of file
Received on Wednesday, 3 August 2005 23:38:33 UTC