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[Bug 7015] New: Separation of Verb and Content

From: <bugzilla@wiggum.w3.org>
Date: Thu, 11 Jun 2009 23:50:14 +0000
To: public-ws-resource-access-notifications@w3.org
Message-ID: <bug-7015-2780@http.www.w3.org/Bugs/Public/>

           Summary: Separation of Verb and Content
           Product: WS-Resource Access
           Version: FPWD
          Platform: PC
        OS/Version: Windows NT
            Status: NEW
          Severity: normal
          Priority: P2
         Component: Transfer
        AssignedTo: public-ws-resource-access-notifications@w3.org
        ReportedBy: geoffbu@microsoft.com
         QAContact: public-ws-resource-access-notifications@w3.org

Background and details:

The submitted version of WS-Transfer allows the body element of a SOAP message
to directly contain a resource representation.  Some members of the working
group strongly desired to insert a wrapper element around the resource
representation so that WSDL descriptions of such messages would conform to WS-I
Basic Profiles.  

This could have been achieved by defining a single wrapper element, having the
same element name regardless of which WS-Transfer message it would appear in. 
However, the working group defined multiple wrapper elements, such that each
WS-Transfer action (as expressed in the wsa:Action header) would correspond
uniquely to a distinct wrapper element.

Having multiple, distinguished wrapper elements encourages fracturing of the
web services community around two different and non-interoperable
implementation choices.  Here is why:

Historically, before WS-Addressing [2] became a standard, many web service
implementations used the first child element of the SOAP body in order to
determine which operation to invoke.  The first child element name effectively
became the “verb” used to route web service messages.  WS-Addressing
standardized “action” semantics in the SOAP header (using the action URI) to
achieve this goal and thus required no semantics at all in the SOAP body.  This
action URI became the new way to define the verb, and also aligned with the
principles used in HTTP [3] (i.e. that the HTTP body should contain content,
not dispatch information).

WS-Transfer [4] contains a normative reference to WS-Addressing, and is
designed around the dispatch of messages using the action URI.

The decision here, to require that the name of the first child element match
the action, makes ambiguous the role of the first child element in defining the
verb used for routing messages.  Implementers could incorrectly dispatch using
the first child element as the verb, rather than support the WS-Addressing
action as the verb.  Replication of information always decreases
interoperability, and this continued polarization has to stop if
interoperability is to be achieved.  This interoperability issue is real, not
just hypothetical.

Use a single wrapper.

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Received on Thursday, 11 June 2009 23:50:20 UTC

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