W3C | Submissions

Team Comment on Web Services Policy Attachment for Endpoint Reference (WS-PAEPR) Submission

W3C is pleased to receive the Web Services Policy Attachment for Endpoint Reference (WS-PAEPR) from Axway, BEA Systems, Inc., JBoss Inc., Nokia, Oracle, and Progress Software Corporation.

This Submission defines a mechanism to attach policies written using the Web Services Policies 1.5 Framework specification to an endpoint reference, defined by the Web Services Addressing 1.0 - Core specification.

Endpoint references

The Web Services Addressing 1.0 - Core specification defines endpoint references (EPR), a construct designed to exchange endpoint information, such as references to specific service instances that are created as the result of stateful interactions. For example, one might receive an EPR for the intended receiver for replies to or faults related to a message. An EPR may contain metadata that describes the behavior, policies and capabilities of the endpoint. It is not necessarily a complete statement of the metadata pertaining to the endpoint.

Attaching Policies to Endpoint References

The Submission defines a mechanism for including policies, as defined in Web Services Policy 1.5 - Framework specification, in the metadata contained within the EPR. It also indicates how to calculate the effective policy for the endpoint, by providing a simple algorithm to combine the policies. The specification mentions the case of calculating the effective policy for an EPR that would contain WSDL 1.1 or WSDL 2.0 description within its metadata. It should be noted here that the June 2007 version of the Web Services Addressing Metadata specification indicates that the sections 2.1 Referencing WSDL Metadata from an EPR and 2.2 Embedding WSDL Metadata in an EPR, defining how to reference WSDL Metadata from an EPR and how to embed WSDL Metadata in an EPR, are considered at risk.

Relation to current work

Web Services Policy Working Group

The Web Services Policy Working Group defines the policy language Web Services Policy 1.5. It also provides attachment mechanisms to UDDI 2.0/3.0 and WSDL 1.1/2.0. The Working Group investigated the issue of attaching policies to EPR and decided not to address it (see issue 4129). Web Services Policy 1.5 - Attachment, section 3.4 External Policy Attachment, does however give an example of the external attachment mechanism with an endpoint reference domain expression.

Web Services Addressing Working Group

The Web Services Addressing Working Group also had an issue on attachment of policies to an endpoint (see issue lc137). The Working Group decided to close the issue, hoping that a new Group would be willing to tackle the issue.

Web Services Metadata Exchange

Web Services Metadata Exchange is a specification produced by a separate group of companies. It defines an encapsulation format for metadata, specifically for Web services policies, descriptions, and schemas (ie WS-Policy, WSDL, and XML Schema), and defines mechanisms to retrieve metadata. This format can be used within the metadata section of an EPR (see section 6 Metadata in Endpoint References).

Next steps

This new Submission will be brought to the attention of the Web Services Addressing and Web Services Policy Working Groups as well as the Web Services Coordination Group. The W3C would be however concerned if one of the Groups would decide to start the work using the Submission as a basis, without considering the Web Services Metadata Exchange specification. The W3C is interested in avoiding competing solutions in the Web Services space and in working with the various parties to come up with a common solution.

Author: Philippe Le H├ęgaret
$Date: 2007/08/02 18:17:34 $