W3C Workshop on Constraints and Capabilities to Explore Next Web Services Layer

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Workshop Draws Numerous Speakers Interested in Web Services Constraints and Capabilities Framework


http://www.w3.org/ -- 12 October 2004 -- Leading Web services to its full potential, the World Wide Web Consortium has organized a Workshop on Web Services Constraints and Capabilities, hosted by Oracle, on 12-13 October 2004, in California (USA). During the two-day event, attendees will discuss vocabularies for describing common constraints and capabilities and frameworks for combining them. Workshop participants will also discuss the relation of this work to other core Web services work being standardized at W3C, as well as the relation of the work to other Web technologies.

"I am pleased to see so much interest among W3C Members to share crucial information about Web Services through the W3C process. The need for Web Services standards is becoming more and more important as we automate the use of so many Web Services applications. This in turn sets the direction for new work," said Tim Berners-Lee, W3C Director.

A W3C workshop is an opportunity to bring together W3C Members and the public to discuss possible future directions for W3C work. After a successful workshop, W3C may initiate a new Working Group to develop a standard in that area.

Sharing Vocabularies for Describing Web Services

The Web Services Description Language (WSDL2.0) specification provides the basic building blocks for describing a Web service. Designers may achieve more detailed descriptions of Web services constraints and capabilities by using domain-specific vocabularies, implemented as extensions to the basic WSDL model.

"Various aspects of a Web service may require description," explained Mark Nottingham (BEA Systems), co-Chair of the workshop. "This includes its constraints (e.g., 'You must use HTTP authentication when accessing this service') and its capabilities (e.g., 'I can support GZIP compression'). Likewise, clients accessing Web services have constraints and capabilities of their own to consider. This workshop is being held to discuss the establishment of a standard framework for the expression of such constraints and capabilities and their association using technologies such as SOAP, WSDL, and HTTP."

In order to participate in the workshop, W3C Members and the general public were required to submit position papers. The more than 35 position papers received indicate substantial interest in this topic. The papers address subjects ranging from specific problem domains (such as security, reliable messaging, and internationalization), to the use of rule-based languages for building vocabularies, to the construction of a general framework to accommodate a wide variety of vocabulary design needs.

To help focus discussion, participants were asked to address in their position papers a pre-selected use case. Participants were asked to discuss how their proposal would allow a Web service designer to stipulate (among other things) that (1) clients are required to support a reliable messaging protocol, (2) clients are required to encrypt a specific header with WS-Security using an X.509 or user name security token in order to send an acceptable request message, and (3) the service has a P3P privacy policy associated with it. Workshop attendees will discuss vocabularies for expressing policies, how to communicate those policies and policy decisions to other parties, how to manage policies (e.g., how to handle delegation or revocation), and the relation of this work to existing work at W3C and elsewhere.

W3C Actively Developing Core of Web Services Architecture

This workshop represents one of several Web services initiatives at W3C at this time. W3C Members have already selected W3C as the organization to develop core Web services specifications that have become W3C Recommendations or are on their way, including SOAP 1.2 and WSDL 2.0.

"W3C has been working on the core architecture of Web Services since 2000 and Constraints and Capabilities is the next fundamental piece of it," said Philippe Le Hégaret, Architecture Domain Leader for W3C and co-Chair of the workshop. "In this work we are looking at extending WSDL 2.0 and its expressiveness, in ways that allow us to combine existing and future Web Services extensions, such as the security mechanisms."

In August 2004, two new SOAP specifications advanced to Candidate Recommendation status, indicating that W3C considers them ready for implementation: "SOAP Message Transmission Optimization Mechanism" and "Resource Representation SOAP Header Block." The WSD Working Group also issued a "Last Call" for three WSDL 2.0 specifications, indicating that the Working Group believes that the specifications fulfill the Working Group's technical requirements.

On 7 October 2004, W3C launched a new Web Services Addressing Working Group to further work in that core area. The Workshop on Web Services Capabilities and Constraints will help to determine the direction of future Web services work at W3C. It is likely that progress in the area of component descriptions will also accelerate the development of related specifications such as WSDL 2.0.

In addition to the Working Groups that are developing these Web services specifications, W3C representatives are engaging the community on the case for W3C's Web services standards and their relation to other Web standards developed at W3C. Chief Operating Officer Steve Bratt and David Booth (W3C Fellow from Hewlett-Packard) will be speaking and conducting a workshop on WSDL 2.0 at the Gartner Application Integration and Web Services Summit mid-November. Also mid-November, W3C Director Tim Berners-Lee will be a keynote speaker at the Second International Conference on Service Oriented Computing.

About the World Wide Web Consortium [W3C]

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. To date, nearly 400 organizations are Members of the Consortium. For more information see http://www.w3.org/


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