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New WS-Addressing chair addresses the endpoint

Last August, BEA, IBM, Microsoft, SAP and Sun Microsystems submitted the WS-Addressing specification to the W3C. WS-Addressing provides transport-neutral mechanisms to address Web services and messages. It also defines XML elements to identify Web service endpoints and to secure end-to-end endpoint identification in messages. In this interview, Mark Nottingham, senior principal technologist at BEA Systems Inc., who was recently elected chair of the Web Services Addressing Working Group, discusses various open issues and looks at how WS-ReliableMessaging, WS-Eventing and WS-Transaction build upon WS-Addressing. He also describes some of the work being done to better integrate the specification with SOAP and Web Services Description Language (WSDL).

What will your duties be as chair of the Web Services Addressing Working Group?
My job is to act as a neutral party that helps the working group move forward. In effect, it's to embody both the W3C Process and the charter of the working group by assuring that we get a result that best represents consensus in the community, as well as being on target and on time.

In practice, this means leading conference calls and face-to-face meetings, helping drive discussion forward and making sure that all points of view are understood, as well as assuring that people attend meetings, keeping an issues list and lots of other administrivia.

Where is WS-Addressing in terms of ratification?
So far, we've been able to stick to the spirit of the aggressive schedule laid out in our charter. At our last face-to-face meeting in January, we resolved what many believed to be our two most contentious issues. I'm hopeful that we'll be able to deliver Last Call Working Drafts of our first two documents (the "core" document and its binding to SOAP) shortly after our next face-to-face meeting, at the W3C Technical Plenary in early March. After that, we'll still need to address any issues brought up in comments, and then assure interoperability during our Candidate Recommendation phase.

What areas of the specification are you focusing on?
Many of the issues have to do with the integration of WS-Addressing into SOAP and WSDL. As we've worked through those [issues], we've discovered areas that needed more precise specification or modification.

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Can you provide some detail on the three recently released WS-Addressing working drafts: WS-Addressing Core, SOAP Binding and WSDL Binding? Why was the spec split up into these three areas?
Our charter required us to produce three separate deliverables. Doing so allows more flexibility in the future; for example, having a separate Core and SOAP binding allows Addressing properties to be bound to other protocols down the road.

Can you describe the relationship between WS-Addressing and WSDL 1.1?
WS-Addressing can be thought of as a set of message headers that perform common functions, like identifying a particular instance of the message, showing who sent it and where it's going, and where to send other messages [e.g., replies] to.

WSDL, on the other hand, is a language for describing the messages and other constructs that make up a Web services protocol. WSDL 1.1, while widely used, has a number of interoperability problems and self-contradictions that make it difficult to use. The group is now working on WSDL 2.0 to fix these and assure better coordination with other specifications, like WS-Addressing and SOAP 1.2.

How does the work being done in WS-Addressing relate to work being done in other emerging specifications, such as WS-ReliableMessaging, WS-Eventing and WS-Transaction?
These and other specifications are already being built upon early drafts of WS-Addressing. Once it is standardized by the W3C, it will be a stable part of the Web services stack that other specifications can confidently reference.

What kind of security issues need to be considered when communicating between endpoints?
So far, WS-Addressing relies on other specifications, like WS-Security, XML Encryption and XML Digital Signature to secure communication, as part of the overall Web services stack. One of our open issues is to examine this area more closely, to make sure it's possible to use WS-Addressing in a secure fashion.

Are there competing specs out there and what's being done to converge them?
The most obvious is Web Services MessageDelivery (WS-MD), a previous member submission to the W3C. Happily, many of the authors of WS-MD are participating in the working group, assuring that the requirements of WS-MD are heard and considered.

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