The World Wide Web Consortium has announced the publication of Architecture of the World Wide Web, Volume One as a W3C Recommendation. The document was developed by the W3C Technical Architecture Group (TAG), edited by Ian Jacobs (W3C) and Norman Walsh (Sun Microsystems).

The W3C Technical Architecture Group began its work in 2001, chartered to "document and build consensus around principles of Web architecture and to interpret and clarify these principles when necessary." According to Tim Berners-Lee, W3C Director, and co-Chair of the TAG the document "emphasizes what characteristics of the Web must be preserved when inventing new technology, [taking] notice where the current systems don't work well, and as a result show weakness."

The TAG's charter understands "Web architecture" to refer to "the underlying principles that should be adhered to by all Web components, whether developed inside or outside W3C. The architecture captures principles that affect such things as understandability, interoperability, scalability, accessibility, and internationalization."

The Architecture of the World Wide Web is presented in seven principal sections. Individual entries are categorized as belonging to Principles, Constraints, or Good Practice Notes. Following an Introduction, the section on 'Identification' discusses Benefits of URIs, URI/Resource Relationships, URI Comparisons, URI Schemes, URI Opacity, Fragment Identifiers, and Future Directions for Identifiers. Section 3 on 'Interaction' covers Using a URI to Access a Resource, Representation Types and Internet Media Types, Inconsistencies between Representation Data and Metadata, and Safe Interactions, and Representation Management.

The Architecture document's Section 4 on 'Data Formats' treats Binary and Textual Data Formats; Versioning and Extensibility; Separation of Content, Presentation, and Interaction; Hypertext; XML-Based Data Formats, and Future Directions for Data Formats. The final Sections 5-7 contain General Architecture Principles (Orthogonal Specifications; Extensibility Error Handling Protocol-based Interoperability), Glossary, and References.

The TAG has also prepared a standalone Summary of 'Architecture of the World Wide Web, Volume One' which presents the Architecture Document's principles, constraints, and good practice notes in an abbreviated format. Each entry has a title, the type of entry (principles, constraints, or good practice note), designation of the section of the Architecture Document where it is discussed, followed by the entry text.

According to the Recommendation's abstract, "The World Wide Web uses relatively simple technologies with sufficient scalability, efficiency and utility that they have resulted in a remarkable information space of interrelated resources, growing across languages, cultures, and media. In an effort to preserve these properties of the information space as the technologies evolve, this architecture document discusses the core design components of the Web. They are identification of resources, representation of resource state, and the protocols that support the interaction between agents and resources in the space. We relate core design components, constraints, and good practices to the principles and properties they support."

Following the publication of Architecture of the World Wide Web, Volume One the W3C TAG reports that it is continuing to track "principles that are currently being tested in rapidly evolving areas. Future TAG publications will build on Volume One with lessons learned from integrating Web services, the Semantic Web, and mobile Web. A single shared Web space is of global benefit. This goal can only be achieved if all the parts work together harmoniously."

Bibliographic Information

Architecture of the World Wide Web, Volume One. W3C Recommendation. 15-December-2004. Edited by Ian Jacobs (W3C) and Norman Walsh (Sun Microsystems, Inc). Developed by W3C Technical Architecture Group (TAG). Authors and contributors are listed below. Version URL: http://www.w3.org/TR/2004/REC-webarch-20041215/. Latest version URL: http://www.w3.org/TR/webarch/. Previous version URL: http://www.w3.org/TR/2004/PR-webarch-20041105/.

"This document was authored by the W3C Technical Architecture Group which included the following participants: Tim Berners-Lee (co-Chair, W3C), Tim Bray (Antarctica Systems), Dan Connolly (W3C), Paul Cotton (Microsoft Corporation), Roy Fielding (Day Software), Mario Jeckle (Daimler Chrysler), Chris Lilley (W3C), Noah Mendelsohn (IBM), David Orchard (BEA Systems), Norman Walsh (Sun Microsystems), and Stuart Williams (co-Chair, Hewlett-Packard). The TAG appreciates the many contributions on the TAG's public mailing list [www-tag@w3.org], which have helped to improve this document...

In addition, contributions by David Booth, Erik Bruchez, Kendall Clark, Karl Dubost, Bob DuCharme, Martin Dürst, Olivier Fehr, Al Gilman, Tim Goodwin, Elliotte Rusty Harold, Tony Hammond, Sandro Hawke, Ryan Hayes, Dominique Hazaêl-Massieux, Masayasu Ishikawa, David M. Karr, Graham Klyne, Jacek Kopecky, Ken Laskey, Susan Lesch, Håkon Wium Lie, Frank Manola, Mark Nottingham, Bijan Parsia, Peter F. Patel-Schneider, David Pawson, Michael Sperberg-McQueen, Patrick Stickler, and Yuxiao Zhao are gratefully acknowledged."

From the W3C Announcement

In November 2001, W3C responded to a clear demand from the Web community and the W3C Membership to write down a description of the architecture of the Web. Aspects of the architecture have been described and debated many times in the past, but the overall principles which make the Web as we know it work, and work well, have not previously been described in a single, coherent document by a group of acknowledged experts, and reviewed in such a focused manner by the community.

"All TAG participants, past and present, have had a hand in many parts of the design of the Web," explains Tim Berners-Lee, W3C Director, and co-Chair of the TAG. "In the Architecture document, they emphasize what characteristics of the Web must be preserved when inventing new technology. They notice where the current systems don't work well, and as a result show weakness. This document is a pithy summary of the wisdom of the community."

The TAG conducted its work on an active, public mailing list, which helped ensure that its description of the Web reflected the real world concerns of developers. In some cases, principles were found to be widely applicable. In others, principles had a more restricted domain or represented tradeoffs between conflicting requirements. The TAG documented the points to be considered, to allow technology developers to make well-informed choices. "The discussion process produced a wider appreciation of the design principles on which the Web is based," notes Chris Lilley, TAG participant, "and the Architecture document crystallizes that shared understanding for easy reference."

Essential Web design principles should not be merely understanding among small groups of expert developers. By collecting and debating issues in an open forum, the TAG has documented and clarified those principles which have stood the test of time and are widely implemented. As the Web continues to grow on an unprecedented scale, new generations of developers need to have a concise reference to the important design concepts. Newer additions can then take advantage of a secure and scalable foundation. It is gratifying to note that some university courses in Distributed Systems have already taken up the TAG's work as a course text, and it is already influencing product design.

Volume One of the Web Architecture significantly advances the state of the art, documenting long-established principles which are well understood and proven in use. In addition, the TAG is tracking principles that are currently being tested in rapidly evolving areas. Future TAG publications will build on Volume One with lessons learned from integrating Web services, the Semantic Web, and mobile Web. A single shared Web space is of global benefit. This goal can only be achieved if all the parts work together harmoniously.

The W3C was created to lead the Web to its full potential by developing common protocols that promote its evolution and ensure its interoperability. It is an international industry consortium jointly run by the MIT Computer Science and Artificial Intelligence Laboratory (CSAIL) in the USA, the European Research Consortium for Informatics and Mathematics (ERCIM) headquartered in France and Keio University in Japan. Services provided by the Consortium include: a repository of information about the World Wide Web for developers and users, and various prototype and sample applications to demonstrate use of new technology. More than 350 organizations are Members of W3C.