[October 2005]Paul Downey, Chair, BT
The Working Group follows the rules and requirements of the latest operative version of the World Wide Web Consortium Process Document. In the event of a conflict between this document and the W3C Process Document, the W3C Process Document shall take precedence.
The mission of this Working Group is to define a set of XML Schema patterns that will be efficiently implementable by the broad community who use XML databindings. Patterns which may prove useful to model include abstractions of structures common across a wide variety of programming environments, such as hash tables, vectors, and collections. There are several ways of representing such abstracted data structures and Web Services toolkits are currently using ad hoc technologies to infer the most suitable language mapping when processing XML Schemas. Agreeing on a set of XML Schema patterns for which databinding optimizations can be made will facilitate the ability of Web services and other toolkits to expose a more comprehensible data model to the developer.
The Working Group should identify a set of common data abstractions
and define a set of recommended XML Schema patterns for them for the purpose of
simplifying the mapping of XML Schemas to the identified data structures.
Those patterns must be independent of any particular
programming language, database or processing environment.
For example, keys from
a hash table can be represented using the
xs:key component, or the
component, and possibly in other ways.
The Group will also develop a method of identifying the usage of those
patterns so that conformance of an XML Schema to those patterns
can be verified.
This group will also look at the issue of versioning of data structures and the impact on the XML Schema patterns. For example, suppose a programmer uses one version of a class and a later version of that class adds a new property. Consider an application that uses one version of a schema pattern for which a later version adds a new elements and/or attributes. The Working Group will examine how such a change might affect applications as Web Services compatibility, and what approach developer may adopt to reduce the risk of incompatibility across versions when accessing the corresponding datastructures.
As the TAG and other groups have discussed, it is important to consider evolution goals early in the design process. The Technical Architecture Group, the Web Services Description Working Group, and the XML Schema Working Group (see XML Schema Versioning Use Cases) are all studying versioning and extensibility issues. It is therefore expected that this Working Group will follow the results of those discussions, or take active part in them.
Profiling XML Schema for Web Services is out of scope: While the recommended patterns are not expected to use every possible feature of XML Schema, Web Services toolkits are expected to provide full support of XML Schema.
Direct mapping from the patterns into a specific programming language, database or other environment are out of scope; the goal is to provide interoperability across different programming languages, database and processing environments each with their own native data representations.
We expect this work to unfold in two successive set of patterns:
The expiration date of this charter is 30 September 2007.
The milestones follow the roadmap, outlined above.
The Working Group should coordinate its efforts with the W3C Working Groups involved in the Web Services and XML Activities, in particular the Web Services Description Working Group and the XML Schema Working Group, as well as the Technical Architecture Group.
Various efforts have been accomplished outside W3C in order to map the XML Schema constructions in different programming languages (C#, Java, Python, …). The Working Group will also take those external efforts into account.
Effective participation is expected to consume one workday per week for each Working Group participant; two days per week for editors. The Chair shall ensure that the criteria for Good Standing are understood and followed.
To be successful, we expect the Working Group to have 10 or more active participants for its duration.
The initial Chair of this Working Group is Paul Downey, BT.
The initial W3C Team contact is Yves Lafon. It is expected that this Working Group would consume about 0.2 FTE, including administrative logistics.
The Working Group will have distributed and face-to-face meetings.
The Working Group will use a public mailing list, firstname.lastname@example.org.
A Member-only mailing list email@example.com is also available for administrative purposes only.
The proceedings of this Working Group are public, subject to exceptions made by the Chair, after consultation with the Working Group.
This Working Group operates under the W3C Patent Policy (5 February 2004 Version). To promote the widest adoption of Web standards, W3C seeks to issue Recommendations that can be implemented, according to this policy, on a Royalty-Free basis.