Basic XML Schema Patterns for Databinding

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This specification provides a set of basic patterns known to be interoperable between state of the art databinding implementations. The patterns may be used to describe representations of commonly used data structures. The data structures described are intended to be independent of any particular programming language, database or modelling environment.

Version 1.0

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XML &pubday; &pubmonth; &pubyear; http://www.w3.org/2002/ws/databinding/edcopy/basic/basic.html http://www.w3.org/TR/xmlschema-patterns http://www.w3.org/TR/2008/WD-xmlschema-patterns-20080328/ Jonathan Calladine BT George Cowe Origo Services Limited Paul Downey BT Yves Lafon W3C

This section describes the status of this specification at the time of its publication. Other specification may supersede this specification. A list of current W3C publications and the latest revision of this technical report can be found in the W3C technical reports index at http://www.w3.org/TR/.

This is a public Working Group Note produced by the XML Schema Patterns for Databinding Working Group, which is part of the W3C Web Services Activity. This publication as a Working Group Note coincides with the end of the Working Group's charter period, and represents the culmination of the group's work.

Comments from interested parties and incorporates comments received since the first Last Call publication on 2006-11-22 of this document were sent to the public public-xsd-databinding-comments@w3.org mailing list (public archive).

This document was built using evidence and experience gained examining the interoperability of a significant number of state of the art databinding implementations using a test suite, see the Basic Patterns Implementation Report and a collection of implementation reports including the collection of patterns detected from "the wild".

The Working Group also produced an accompanying document, which includes patterns in common use, but which were discovered not to be well supported by state of the art databinding implementations.

Publication as a Working Group Note does not imply endorsement by the W3C Membership. This is a draft specification and may be updated, replaced or obsoleted by other specification at any time. It is inappropriate to cite this specification as other than work in progress.

This document was produced by a Working Group operating under the 5 February 2004 W3C Patent Policy. The W3C maintains a public list of any patent disclosures made in connection with the deliverables of the group; that page also includes instructions for disclosing a patent. An individual who has actual knowledge of a patent which the individual believes contains Essential Claim(s) must disclose the information in accordance with section 6 of the W3C Patent Policy.

US English

Introduction

A databinding tool generates a mapping between documents which conform to an schema and an internal data representation. For example, a Web services databinding tool may use descriptions inside a or document to produce and consume , and messages in terms of data structures in a programming language or data held inside a database.

provides a wide variety of methods for describing the same structure. Conversely an abstract concept such as "null" may be represented in a wide variety of different ways using .

A representative collection of databinding implementations in common use has been used to provide an indication of the "state of the art". State of the art databinding implementations have displayed uneven and inconsistent support of the W3C Recommendation resulting in impaired interoperability and a poor user experience of databinding tools:

rejecting valid documents, rejecting valid instance documents, and making the content of valid instance documents unavailable in mapped data structures.

This specification provides a basic set of example constructs and types in the form of concrete expressions. These patterns are known to work well with state of the art databinding implementations.

Authors of documents may find these patterns useful in providing a better user experience for consumers of their schemata using databinding tools. Whilst it is not possible to guarantee that schemata produced using these patterns will give a good user experience with the universal set of databinding tools, the patterns contained in this specification have been all been tested with a number of different tools covering a variety of different programming languages and environments.

Implementers of databinding tools may find these patterns useful to represent simple and common place data structures. Ensuring tools recognize at least these simple patterns and present them in terms most appropriate to the specific language, database or environment will provide an improved user experience when using databinding tools. It is inappropriate to use this specification to constrain implementation of the Recommendation.

¬ations; &namespaces; Document Conformance

A document claiming conformance to this specification:

MUST use either the UTF-8 or UTF-16 encoding. MAY include the Byte Order Mark (). MUST be a well-formed document MUST be a 'schema document', as defined in , and MUST therefore meet the "Constraints on the representation of schema components in XML" provided therein. MUST only contain element nodes and attribute nodes which form a part of one or more complete patterns contained in this specification. MAY contain additional comment nodes and processing instruction nodes. Implementation Conformance

An implementation that claims conformance to this specification:

MUST be able to process any document conforming to this specification MUST produce a data model exposing all of the element node and attribute node content constrained by the originating document. MUST be able to consume any well-formed document which satisfies local-schema validity against the originating document exposing all of the element node and attribute node content in the data model. MUST be able to produce well-formed instance documents which satisfy local-schema validity against the originating document containing values exposed in the data model. MAY consume well-formed instance documents which do not satisfy local-schema validity against the originating document. MAY allow the production of well-formed instance documents containing values exposed in the data model which do not satisfy local-schema validity against the originating document.

Describing the form of the data model provided by a databinding implementation is beyond the scope of this specification. For example, the unconstrained built-in numeric primitive types, xs:decimal, xs:integer, xs:negativeInteger, xs:positiveInteger, xs:nonNegativeInteger and xs:nonPositiveInteger, do not map directly to native types in many programming languages and are likely to be presented as a toolkit specific construct or more generalised ways, such as a 'string'.

Note that although the patterns contained in this document are defined using , there is no requirement for a conformant implementation to support .

Schema Patterns &patterns-intro;

The xs:schema element MAY be the document element, but MAY also appear within other descriptions such as a or document.

Note, this pattern represents a subset of the native identifier formats supported by many, but not all, implementations and is therefore most likely to be supported by a databinding tools which directly maps an NCName to an native identifier.

The NCName used to declare an attribute MUST NOT be used as the declared NCName of a child element.

Note, this pattern may be further constrained by the regular expression used by the pattern to support databinding tools which directly map an xs:enumeration value to an native identifier.

An document conforming to this specification MUST define a targetNamespace whose value is an absolute URI.

This pattern is designed to capture a reference to a namespace defined within a WSDL document types section.

An document conforming to this specification MUST namespace qualify all locally declared elements using a schema element elementFormDefault attribute value of qualified.

&patterns; References Normative References Henry S. Thompson, David Beech, Murray Maloney, and Noah Mendelsohn, Editors. World Wide Web Consortium. XML Schema, Parts 0, 1, and 2 (Second Edition). W3C Recommendation, 28 October 2004. See http://www.w3.org/TR/xmlschema-0/, http://www.w3.org/TR/xmlschema-1/, and http://www.w3.org/TR/xmlschema-2/. XML Path Language (XPath) 2.0, Don Chamberlin , Anders Berglund, Scott Boag, et. al., Editors. World Wide Web Consortium, 3 Nov 2005. The latest version is available at http://www.w3.org/TR/xpath20/. Namespaces in XML, T. Bray, D. Hollander, and A. Layman, Editors. World Wide Web Consortium, 14 January 1999. The latest version is available at http://www.w3.org/TR/REC-xml-names. World Wide Web Consortium. Extensible Markup Language (XML) 1.0. (Fourth Edition) W3C Recommendation, 16 August 2006. See http://www.w3.org/TR/REC-xml Key words for use in RFCs to Indicate Requirement Levels, S. Bradner, Editor. IETF, March 1997. Uniform Resource Identifiers (URI): Generic Syntax, T. Berners-Lee, R. Fielding, L. Masinter, Authors. Internet Engineering Task Force, January 2005. Available at http://www.ietf.org/rfc/rfc3986.txt. The Unicode Consortium. The Unicode Standard, Version 4.0. Reading, Mass.: Addison-Wesley, 2003, as updated from time to time by the publication of new versions. (See http://www.unicode.org/unicode/standard/versions for the latest version and additional information on versions of the standard and of the Unicode Character Database) Informative References Advanced XML Schema Patterns for Databinding 1.0 , Jonathan Calladine, George Cowe, Paul Downey, Yves Lafon, Editors. World Wide Web Consortium, &advanced-pubmonth;, &advanced-pubyear;. The latest version of Advanced Patterns is available at http://www.w3.org/TR/&advanced-shortname;/. Web Services Description Language (WSDL) Version 2.0 Part 1: Core Language, R. Chinnici, J. J. Moreau, A. Ryman, S. Weerawarana, Editors. World Wide Web Consortium, 6 January 2006. The latest version is available at http://www.w3.org/TR/wsdl20. E. Christensen, et al, Web Services Description Language (WSDL) 1.1, March 2001. SOAP Version 1.2 Part 1: Messaging Framework, M. Gudgin, M. Hadley, N. Mendelsohn, J-J. Moreau, H. Frystyk Nielsen, Editors. World Wide Web Consortium, 24 June 2003. The latest version is available at http://www.w3.org/TR/soap12-part1/. Simple Object Access Protocol (SOAP) 1.1, D. Box, D. Ehnebuske, G. Kakivaya, A. Layman, N. Mendelsohn, H Frystyk Nielsen, S. Thatte, D. Winer, Editors. W3C Member Submission, 8 May 2000. XSL Transformations (XSLT) Version 2.0, M. Kay, Editor. World Wide Web Consortium, 8 June 2006. The latest version is available at http://www.w3.org/TR/xslt20. WS-I Basic Profile 1.1, Web Services Interoperability Organization, April 2004 The latest version and errata is available from http://www.ws-i.org/Profiles/BasicProfile-1.1.html. ISO/IEC 19757-3:2006, Information technology - Document Schema Definition Languages (DSDL) - Part 3: Rule-based validation - International Standards Organization (JTC1/SC34) - Schematron. Unicode Frequently Asked Questions Working with Time Zones, Addison Phillips, Felix Sasaki, Mark Davis, Martin Dürst, Editors. World Wide Web Consortium, 13 October 2005. The latest version is available at http://www.w3.org/TR/timezone/. Data Types & Structures

This section offers one or more patterns which may be used to represent an abstract data structure. Each data structure presented is intended to be independent of any particular programming language, database or modeling environment. No semantics are implied by the order in which patterns are listed for a given abstract data structure.

Null Value Definition A special value used to represent an "unknown", "missing", "not applicable", "uninitialised" or "undefined value". Patterns Default Value Definition A preselected value used by when no alternative is explicitly specified. Patterns none Enumeration Definition A type whose definition contains an exhaustive list of possible values. Patterns Collection Definition A collection of data items, typically contained by a programming language "object", "class", "structure", or "record". Patterns Inherited Collection Definition A collection which extends an existing collection. Patterns Vector Definition An ordered sequence of items of the same type. This construct appears in programming languages as an array or list. Patterns &detecting-patterns; &xpath-idioms; &pattern-summary; &assertion-summary; &schema-summary; &ws-i-conformance; &acknowledgements;