Web Services Metadata Exchange is an initiative of the industry leaders BEA Systems, Computer Associates, IBM, Microsoft, SAP AG , Sun, and webMethods to drive and ensure interoperability for the exchange of Web services metadata.
Web services use metadata to describe what other endpoints need to know to interact with them. Specifically, WS-Policy describes the capabilities, requirements, and general characteristics of Web services; WSDL describes abstract message operations, concrete network protocols, and endpoint addresses used by Web services; XML Schema describes the structure and contents of XML-based messages received by and sent by Web services.
To bootstrap communication with Web services and to retrieve these and other types of metadata, WS-MetadataExchange defines two request-response interactions. When the type of metadata sought is clearly known, e.g., WS-Policy, a requester may indicate that only that type should be returned; where additional types of metadata are being used, or are expected, or when a requester needs to retrieve all of the metadata relevant to subsequent interactions with an endpoint, a requester may indicate that all available metadata, regardless of their types, are expected.
The interactions defined in WS-MetadataExchange are intended for the retrieval of metadata (i.e., service description information) only. They are not intended to provide a general purpose query or retrieval mechanism for other types of data associated with a service, such as state data, properties and attribute values, etc.
Web Services Metadata Exchange fits into the core Web service architecture since it is built on top of XML, XML Schema, WSDL, and WS-Policy.
the draft is available from the SAP IFR site. The authors are planning a feedback workshop in middle October in California. In the workshop, and authors will share with the public the design and the use cases of ws-metadataexchange, and solicit public feedback for further improvements before it can be submitted to a standard organization. The workshop is open to public, please let me know if you or your customer is interested in receiving an invitation.