W3C Workshop on Constraints and Capabilities for Web Services


Oracle Conference Center, Redwood Shores, CA, USA

October 12, 2004 - October 13, 2004

Paper deadline is August 27, 2004.

Various aspects of a Web service may require description. 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 when accessing services.

Many such aspects are typically associated with a number of orthogonal problem domains; for example, it may be desirable to describe constraints and capabilities (also, "policy") regarding security, reliable messaging and message serialization for a particular endpoint. A domain-neutral means of expressing the relationships between policies (e.g., "You MUST use HTTP Authentication and MAY use GZIP compression") would allow a particular aspect to be defined without reference to other domains.

Additionally, Web services provide a number of means of associating metadata (and, therefore, constraints and capabilities) with services; for example, WSDL, UDDI, HTTP and SOAP headers all might allow association of such information with a particular service. It would be advantageous to abstract the association of such metadata with a Web service from its expression, to avoid duplication of effort and allow new association mechanisms to be easily defined.

This Workshop is being held to discuss the establishment of a framework for the expression of such constraints and capabilities and their association with Web services, in order to promote their interoperability and scalability. It is expected that discussion at the Workshop will lead to a common understanding of the problem space and provide recommendations to the W3C regarding further work.