W3C Technical Architecture Group Status Report (August - December, 2010)

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

Administration and participation


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

The next F2F meeting of the TAG will be held 8-10 February 2011 at the offices of the W3C in Cambridge, MA.

Membership changes

The TAG election nomination period closed at the end of November. There were three nominees for three open positions, so all nominees were elected without a vote (section 2.5.2 of the W3C Process Document). The members who were elected or re-elected are:

All terms begin 1 February 2011 and end 31 January 2013. A complete list of TAG participants is provided below. On position on the TAG remains open for appointment by the Director.

Core Mechanisms of the Web

During this period, the TAG worked on the following areas relating to core mechanisms of the Web. Much of this work was done in cooperation with the IETF:

Mime and the Web

The MIME system was originally created for use with e-mail, but is now also the primary means of typing representations in HTTP. Although the use of MIME on the Web has been in many respects very successful, there are some problems and inconsistencies, relating in part to its history as an e-mail technology. Under the auspices of the TAG, Larry Masinter has prepared Internet Draft: MIME and the Web (draft-masinter-mime-web-info-02), which explores some of the issues, and which suggests development of a new Best Common Practice for registration of Internet Media Types and Charsets.

Internationalized Resource Identifiers

The TAG has been actively following, and on occasion commenting on security and other concerns relating to the adoption of IRIs and Internationalized Domain Names (IDNS) on the Web.

Fragment identifiers

The TAG contributed to community discussion of at least two issues relating to use and interpretation of fragment identifiers (I.e. the part of a URI that follows a "#"):

Domain name persistence

The TAG continues to explore steps that the W3C might take to facilitate the use of URIs, and in particular http-scheme URIs, as stable identifiers that can be relied upon to remain associated with the intended resource over a very long period of time. Such stable identifiers are required, for example, for references to scholarly publications, for use in libraries, etc. For a variety of reasons, URIs are perceived not to have the required characteristics today. Well known issues relate to the way in which the DNS names are assigned and reassigned, the lack of a means of assigning such a DNS name for more than a few years at a time, etc. Jonathan Rees has been leading the TAG's efforts to understand the requirements and concerns, and to propose steps that might make URIs more appropriate for persistent references.

IETF Liaison

At the Nov. 2010 Technical Plenary, the TAG met with Alexey Melnikov, who was at that time outgoing Application Area Director for the IETF. The aim was to facilitate coordination between the W3C and the IETF (minutes).


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.

During this period, the TAG opened a new TAG issue: (ISSUE-67: HTML and XML Divergence), and it created an informal group to explore improved architectural synergy between XML and HTML5. This group includes some members of the TAG, but it consists primarily of recognized experts from both the HTML and XML communities. Former TAG member Norm Walsh has agreed to chair this effort; weekly calls are being held, and there is an active e-mail discussion on the public list public-html-xml@w3.org.

At the technical plenary in November, the TAG and HTML WG chairs discovered that an administrative error had caused confusion as to whether document http://dev.w3.org/html5/spec/author/ would be carried forward on the Recommendation track. This is of concern to the TAG, because that document is central to the agreed resolution of an earlier TAG request for publication of a language reference for HTML5. While at TPAC, HTML WG chair Paul Cotton sent a note and opened HTML WG ACTION-190 to ensure that the necessary draft will indeed be carried forward on the Recommendation track. The TAG very much appreciates the quick and helpful response of the HTML WG in resolving this problem.

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. The TAG also met with the Web Applications Working Group at the November 2010 Technical Plenary in Lyons. The following sections describe a few of the application-related areas in which the TAG has been active:

API Design for Web Applications

The TAG discussed a number of issues relating to the design of APIs for Web applications. Specifically, we considered techniques that might be used to support evolution of such APIs from one version to another, and in particular the benefits of using a consistent architecture across the families of APIs for which the W3C (and perhaps others) are responsible.

We also discussed the benefits of API "minimization" as an approach to reducing unnecessary exposure of user data. The concern is that certain existing APIs return data in bulk. For example, an application using an API to retrieve a phone number might also be given the user's address, age, e-mail address, etc., all of which might reside together in an address book entry. If the API is minimized or factored to provide information in smaller but still useful groupings, then access control can be achieved at a finer grain, and unnecessary disclosure of information may be reduced.

TAG member Dan Appelquist has agreed to write an initial draft of a TAG Finding on Web Application APIs.

Client-side state

TAG member Ashok Malhotra is revising a draft TAG Finding on Client-side State in Web applications, adapting earlier work that was done by outgoing TAG member T.V. Raman. The traditional "Web of Documents" tends to involve little if any manipulation of state at the client, except for very localized control of things like scrolling and history lists. With AJAX-style Web applications, the use of URIs and other state-related mechanisms like cookies becomes more complicated. The relationship between the URI that the user initially accesses, the data that's actually displayed, and the URIs that are shown in address bars and history lists, is not as clear as with traditional uses of the Web. The draft finding explores these issues, with the intention of eventually suggesting best practices for the construction of such applications.

Client-side storage

In addition to the relatively short-lived "state" discussed above, Web applications also make use of facilities such as SQL stores or HTML5 Web Storage to preserve data between browser sessions. The TAG is exploring best practices for use of such storage, and for using (when appropriate) URIs to identify the information stored, and is considering the pros and cons of maintaining local/remote transparency (consider an e-mail application: should the e-mail be accessed using the same URI, regardless of whether the access is to a server, or to a copy of the e-mail in local Web storage?) Ashok Malhotra is drafting a finding that explores these concerns.


During the period covered by this report, TAG members participated in two privacy workshops:

  1. The W3C Workshop on Privacy for Advanced Web APIs, 12 & 13 July 2010, London
  2. The Internet Architecture Board's Internet Privacy Workshop, 8 & 9 December 2010 (co-sponsored by W3C, ISOC, and MIT

TAG member Daniel Appelquist was instrumental in organizing both of these, and the IAB workshop resulted in several proposed work items for the W3C (see wrapup slides from the workshop). The TAG does not expect to be directly responsible for W3C responses to these proposals, but we are taking the lead in working with Thomas Roessler and others to ensure that the W3C gives them suitable consideration.

Metadata access and representations

The TAG continues to explore the use of the Web for storing and retrieving metadata, and for associating that metadata with the data to which it applies. At the TAG's October face-to-face meeting, Jonathan Rees offered an informal outline of concerns relating to metadata. Jonathan has agreed to produce by 1 April 2011 a first draft of a TAG Finding on Metadata Architecture.

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. Peter Linss (Hewlett Packard)3
  5. Ashok Malhotra (Oracle)3
  6. Larry Masinter (Adobe)3
  7. Noah Mendelsohn (Unaffiliated) (Chair)2,4
  8. Jonathan Rees (Creative Commons)2
  9. T. V. Raman (Google)1
  10. Henry Thompson (U. of Edinburgh)2

Noah Mendelsohn, TAG co-chair

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