TAG work in recent months, October 2008

[This summary is a minor update of our previous summary published in August 2008]

The core technologies of the Web are HTML, HTTP, and URIs, and the work of the W3C Technical Architecture Group (TAG) continues to focus on the corresponding areas of formats, protocols, and naming.

Formats: HTML and ARIA, Namespace Documents

As design of Accessible Rich Internet Applications (WAI-ARIA) matured in the WAI Protocols and Formats Working Group (PFWG) and work started on integration with host languages, especially HTML, the TAG noted the use of an ad-hoc namespace mechanism: an aria- prefix on a collection of attributes. The TAG sent some questions and suggestsions on 14 May regarding the costs and benefits of this ad-hoc mechanism versus using XML Namespaces; after consideration of the deployment costs and benefits, the conclusion of the TAG on 2 June was to accept that the most pragmatic short-term approach is indeed to use names beginning with aria-. URI-based distributed extensibility remains a topic of concern which the TAG discusses under issue tagSoupIntegration-54. The TAG devoted half of its 3-day September F2F to the topic of  "HTML and The Web". The TAG plans to meet with the HTML WG during TPAC 2008 to discuss Modularisation of the HTML5 specification.

The TAG published a finding on Associating Resources with Namespaces, which addresses issue namespaceDocument-8. The finding suggests conventions, from ordinary HTML to dialects using RDDL and GRDDL to RDF, OWL, and XML Schema, for documenting namespaces and for linking associated resources. This 25 June 2008 revision of the finding incorporates editorial work following from our February discussion in Vancouver.

While still in draft form, The Self-Describing Web was updated 12 May 2008 and 8 September 2008 it discusses features of the Web that support reliable, ad hoc discovery of information, including formats such as Atom, RDFa, GRDDL, XML, and RDF.

Work continued on ISSUE-41, What are good practices for designing extensible XML languages and for handling versioning? The 20 May 2008 draft of Extending and Versioning Languages: Compatibility Strategies incorporates a number of reviews comments. The TAG reviewed the 12 September 2008 during its September F2F and decided to include a formalism based on work by Jonathan Rees. Finding a concise way to distill the experience from a large history of examples continues to be a challenge.

Protocols: widget packaging, HTTP scalability, linking

The TAG has opened a new issue, uriBasedPackageAccess-61, in response to a request for support from the Web Applications Formats (WAF) community to consider URI based access and reference to items within a web accessible package. The TAG expects to help address the requirements of not only the WAF community in support of their current work on widgets but also related situations that involve reference within and into packaged structures on the web. The TAG plans to meet with the WebApps WG on this topic during TPAC 2008

In a 19 June discussion of issue scalabilityOfURIAccess-58, the TAG encouraged use of XML catalogs as a caching mechanism to mitigate the load that automated access to DTDs and schemas put on the W3C web site.

Protocol support for linking, e.g. from non-hypertext formats, was in early drafts of HTTP but did not receive enough implementation experience to be ratified in RFC 2616 in June 1999. An HTTP Header Linking draft of 14 March "clarifies the status of the Link HTTP header and attempts to consolidate link relations in a single registry." A 9 May message from the POWDER Working Group chair explains use cases that seem to be satisfied by an HTTP Link header field. After a lengthy Uniform Access to Metadata thread, the TAG encouraged the use of Link for POWDER, among other scenarios in a 13 Jun message following our 20 May discussion of issue httpRedirections-57.

Also following our May meeting in Bristol, we invited comment on the 2 June draft of Passwords in the Clear, especially from the HTML Working Group and the Web Security Context Working Group. A further draft was discussed at our September F2F and a TAG approved Passwords in the Clear finding was published on 15 October.

Naming: XRIs

The TAG is working on comparing HTTP and DNS to other approaches to persistent naming such as info: and xri: under issue issue URNsAndRegistries-50. While the URNs, Namespaces and Registries draft has been preempted by other work since the last update of August 2006, the TAG discovered a 31 May deadline on a ballot to Approve XRI Resolution v2.0 as an OASIS Standard and summarized its position: TAG recommends against XRI. In an attempt to facilitate dialog after this somewhat awkward step, the TAG and the OASIS XRI TC held a 3 July joint meeting and continue the discussion by email in www-tag with the goals of improving understanding of our respective positions and to publically record points of agreement and if necessary irresolvable disagreement.

Discussion of with the OASIS XRI TC has continued through October 2008 with improving levels of mutual understanding and much less talking past one another. The XRI TC are currently exploring alternate approaches to meeting their requirements using existing URI schemes with the intention of developing an approach aligned with the Architecture of the World Wide Web.

About the Technical Architecture Group

The Technical Architecture Group (TAG) was created in February 2001. Three TAG participants are appointed by the Director and five TAG participants are elected by the Advisory Committee. The mission of the TAG is stewardship of the Web architecture. Included in this mission is building consensus around principles of Web architecture, resolving issues involving Web architecture, and helping to coordinate cross-technology architecture developments inside and outside W3C.

Details on TAG activities can be found from the TAG home page. The TAG meets weekly and sends summaries of its activity to the AC, Chairs, and public TAG mailing list (www-tag archive). The TAG welcomes public discussion of open issues, as well as proposals for new issues, on that same list.

TAG Participants

Following the TAG election results announced in January 2008, the TAG participants are:


Dan Connolly, W3C TAG team contact, August 2008
Stuart Williams, TAG co-chair, October 2008
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