Thank you for your comments on the Web Services Address 1.0 - Metadata specification concerning the default action pattern for WSDL 2.0. The Web Services Addressing Working Group discussed this issue during its June 4th teleconference and I was given the task of relating this discussion to you.
Although the WS-Addressing 1.0 Metadata document refers to a "best practice in WSDL 2.0", the WG was unclear about the intent of these "best practices". The language in Sections 2.3.1 and 2.4.1 of the WSDL 2.0 core document concerns the ability to derive one interface from another whereas the language in Section 4.4. of the WSA Metadata spec (augmented by the memories of the participants in the WG) is about the ability to dispatch an incoming message to the correct handler for the intended WSDL operation (though, obviously, these two concerns are closely related).
The point was raised that the handling of new messages and the handling of fault messages are not symmetric. At the point in which a processor receives a new message, there is no context or other information about that message. The default action pattern for input/output messages allows the service to dispatch the message to the correct handler for the WSDL operation. On the other hand, when the processor receives a fault, it does so as a result of previously sending a message. The "core task", if you will, of the processor receiving a fault is to correlate the fault to the request for which it is a response. Knowing which operation triggered the fault doesn't help you perform this task, since a service consumer may have sent multiple messages for the same operation, some of which caused faults and some of which did not. On the other hand, the [relationship] property (wsa:RelatesTo) of the fault message does allow you to correlate the fault to the request which triggered it.
Another point raised was that changing the default action pattern would impact existing implementations of WS-Addressing 1.0. To the extent that the default action pattern for WSDL 2.0 faults has remained unchanged for some time now (going back to second working draft of the WS-Addressing WSDL Binding specification in January of 2005), it is likely that changing this pattern will break existing implementations of WS-Addressing 1.0. While its true that organizations have no right to expect that a pre-Recommendation specification will not change, it's considered bad form to make these sorts of changes (i.e. changes that are reflected on the wire) at this stage without a compelling reason. Furthermore, such breaking changes shouldn't be made without reflecting the change in the namespace of the specification. Although the default action patterns are specified in the WS-Addressing 1.0 Metadata specification, it seems clear that we would actually have to change the WS-Addressing namespace to indicate to implementations that these patterns have changed (since the "wsam" namespace wouldn't necessarily appear in a fault message).
When the WG weighed the harm of the existing default action pattern for WSDL 2.0 faults against the impact of changing this pattern, it was decided that it would be best to leave that pattern as it is. Consequently this issue was closed with no action.
That being said, there are some actions that should be carried forward into any further work on the WS-Addressing 1.0 Core and Metadata specifications (i.e. as errata, etc.)
1.) The reference to the "WSDL 2.0" best practices in Section 4.4 of the Metadata specification should either be removed or clarified. If clarified they should (a) clearly indicate which "best practices" are being referred to and (b) describe the motivation behind the use of such "best practices".
2.) The intended use of the [action] property in fault messages, specifically within the context of WSDL 2.0, should be clarified. Is it enough to indicate which fault was generated or does the "semantics implied by a fault message" need to include an indication of the operation that generated the fault?
the Web Services Addressing Working Group would like to move Web
Services Addressing 1.0 - Metadata to Candidate Recommendation. Since
the Group decided, after due considerations, to close your issue with no
action , we'd like to hear from you and know if you're ok with us
moving forward or if you would like the Group to reconsider it. We'd
appreciate if you can tell us your position asap. Failing to hear from
you by June 21, we would request the Director to move forward,
|Free forum by Nabble||Edit this page|