W3C Technical Architecture Group Status Report (March - July, 2010)

This is a report from the W3C Technical Architecture Group to the W3C membership on TAG activities from March through July, 2010.


That TAG continues to organize most of its work into three major focus areas:

  1. HTML
  2. Web Application Architecture
  3. Metadata Access and Formats

Sections below discuss each of these, as well as TAG work in some other areas. Several TAG members have also agreed to participate in the effort chartered by Jeff Jaffe to refocus the mission of the W3C.


As noted in our previous status report, the TAG has somewhat shifted its focus toward working closely with groups like the HTML WG and others in the community, on issues of immediate importance to emerging specifications. In conjunction with this shift, we have, at least for now, de-emphasized work on Recommendation-track documents and findings.

During this period we have also focused on producing materials that might complement the existing Architecture of the World Wide Web, Volume One with material that would explore more deeply the architecture of Web applications. We have chosen not at this point to settle the likely form of such new material, I.e. whether it might be an additional volume of the Architecture document, revisions to the existing document, new TAG findings, and/or more informal publications such as blog postings. We have also chosen not, so far, to publish new formal working drafts of First Public Working Draft Usage Patterns For Client-Side URI parameters , but we have continued to discuss the technical content of that document. The TAG may or may not decide to take this forward on the Recommendation track.

During the period covered by this report, several less formal drafts and planning documents were prepared and discussed, including MIME and the Web, a blog posting prepared by Larry Masinter. In general, these informal publications have no official status except as part of the record of the TAG's discussions, but it is possible that we will in the future decide to evolve some of these into TAG Findings or Recommendations.


During the period covered by this report, the TAG held or participated in the following face-to-face meetings:

We were joined for part of the March TAG meeting by two of the HTML Working Group chairs and by the HTML activity lead; at the London meeting we discussed long term persistence of URI assignments with Helen Hockx-Yu, who is Web Archiving Programme Manager at The British Library, and with Kevin Ashley, Director of the Digital Curation Centre in the UK.

Membership changes

In June of 2010, Yves Lafon replaced Dan Connolly as W3C Staff Contact for the TAG. Dan was a member of the TAG since the group was first chartered, and he has made extraordinarily valuable contributions to our work. We sincerely thank him for all he has done for the TAG, and wish him the best in his new position.

Yves brings to the TAG not just long experience at W3C, but depth in many of the technologies that the TAG works with. For example, he is an editor of the planned revision to the HTTP RFC (HTTPbis). Yves was able to join us at our June meeting in London, and has already started to make significant contributions to the TAG's work.

Also during this period, Noah Mendelsohn retired from his position at IBM. He has agreed to continue as chair of the TAG, and he has therefore been re-appointed to serve the remainder of his two year term.


The TAG continues to work with the HTML Working Group and other concerned members of the Web community to help refine technical details of the proposed HTML 5 Recommendation. Specific areas in which the TAG has been active in this period include:

The TAG remains concerned that the proposed level of compatibility between HTML 5 and XML may be less than is both desirable and reasonably achievable. Accordingly, the TAG has encouraged Tim Berners-Lee to gather members of the Web community, including W3C-members and non-members alike, to investigate more effective approaches to aligning these technologies. We expect that Tim and the TAG will be working on this in coming months.

Web Application Architecture

As described in our previous report, the Web was initially a system for sharing documents, typically in HTML. Languages like Javascript were then introduced, in part to provide somewhat more dynamic rendering, or for aids to navigation. Later, a new class of Web applications has emerged: the browser is now used as a container for applications that may execute for extended periods, that integrate information from diverse sources, and that provide users with the ability to navigate among states while remaining in the same application. Some of these applications also store information for offline use. HTML is used not as a representation of an individual document, but as a framework for hosting complex program logic, which is typically coded in Javascript.

The TAG continues to focus on the many architectural issues raised by these new Web applications. Indeed, the TAG has asked several of its members to prepare drafts of analyses that might eventually contribute to new TAG publications in this area. During the period covered by this report, we reviewed several such early drafts, and we specifically discussed the following technical issues, among others:

Metadata access and representations

The TAG continues to explore several issues relating to publishing and accessing metadata on the Web.

Metadata Access

The TAG has since 2003 been tracking an issue titled ISSUE-36: Web site metadata improving on robots.txt, w3c/p3p and favicon etc. Noting with pleasure that the recently adopted RFC 5785: Defining Well-Known Uniform Resource Identifiers (URIs) by M. Nottingham and E. Hammer-Lahav appears to address this need in an effective and standardized way, the TAG resolved in July to close its issue. The TAG thanks the editors of the RFC for their patient attention to its concerns during the development of the new Web site metadata standards.

The TAG has also been tracking progress of two related IETF drafts: Web Linking, and LRDD: Link-based Resource Descriptor Discovery.

Other topics

In addition the primary focus areas discussed above, the TAG did work in several other areas:

HTTP Semantics

As noted in our previous report, an informal interest group has been attempting to establish formal semantics for the HTTP protocol. Phone calls are held several times per month, and discussion is held on the public-awwsw@w3.org (archives). Although this is not a formal effort of the TAG, it was inspired in part by discussions held at the TAG. During the period covered by this report, TAG members Jonathan Rees and Dan Connolly have both summarized for the TAG formal methods that appear promising as tools for expressing the semantics of HTTP.

Fragment identifiers in application/____+xml media types

At its London F2F, the TAG noted that drafts of a proposed revision to RFC 3023 (RFC 3023bis) require that generic processors of application/____+xml family media types interpret URI fragment identifiers as XPointers, I.e. as if the type were application/xml. Although the TAG believes this is desirable in principle, we noted that at least one widely deployed media type, application/rdf+xml, requires a different interpretation of its fragment identifiers. The TAG therefore proposed that generic processing of fragment ids be eliminated from RFC 3023bis. Some of the responses to this suggestion expressed strong concern, and the TAG expects to consider those responses in coming weeks.

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 via teleconference and several times each year in person. Summaries (such as this one) of the TAG's activity are provided periodically to the W3C Advisory Committee, W3C working group chairs, and to the 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. The TAG's previous status report was published in March, 2010.

TAG Participants

  1. Tim Berners-Lee (W3C) (Chair)
  2. Dan Appelquist (Vodafone)2
  3. John Kemp (Nokia)1
  4. Ashok Malhotra (Oracle)3
  5. Larry Masinter (Adobe)1
  6. Noah Mendelsohn (Unaffiliated) (Chair)2,4
  7. Jonathan Rees (Creative Commons)2
  8. T. V. Raman (Google)1
  9. Henry Thompson (U. of Edinburgh)2

Noah Mendelsohn, TAG co-chair

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