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[Bug 7912] New: WS-Mex/All: Consider using Dialect Identifier for implicit operation WSDL?

From: <bugzilla@wiggum.w3.org>
Date: Tue, 13 Oct 2009 21:07:14 +0000
To: public-ws-resource-access-notifications@w3.org
Message-ID: <bug-7912-2780@http.www.w3.org/Bugs/Public/>
http://www.w3.org/Bugs/Public/show_bug.cgi?id=7912

           Summary: WS-Mex/All: Consider using Dialect Identifier for
                    implicit operation WSDL?
           Product: WS-Resource Access
           Version: PR
          Platform: PC
        OS/Version: Windows XP
            Status: NEW
          Severity: normal
          Priority: P2
         Component: All
        AssignedTo: public-ws-resource-access-notifications@w3.org
        ReportedBy: katy_warr@uk.ibm.com
         QAContact: public-ws-resource-access-notifications@w3.org


We resolved 6721 (attaching policy to implicit operations) by introducing a new
WS-MetadataExchange dialect for each specification in order to retrieve its
WSDL.  For example, we introduced the following dialect IRI for WS-Transfer:
http://www.w3.org/2009/02/ws-tra/TransferWSDL

We did not consider simply using the existing WSDL dialect with the namespace
as an identifier. I.e. in order to acquire the WS-Transfer WSDL, the
GetMetadata request could look like this:


   <mex:GetMetadata>
      <mex:Dialect URI="http://schemas.xmlsoap.org/wsdl"
         Identifier="http://www.w3.org/2009/09/ws-tra"/>
   </mex:GetMetadata>

The advantages to this approach are:

1) There is no need to define a new dialect in each specification.  The
behaviour is defined entirely in WS-MetadataExchange.  Hence we have a solution
applicable to all specs whose operations may be implicit, even if they are not
part of the WS-RA group of specifications.  

2) The WS-MetadataExchange spec states:

 "If there is more than one metadata unit with the same Dialect, e.g., more
than one XML Schema document, including them all, one per Metadata Section, is
explicitly encouraged." 

This means that a client could receive all the WSDLs it needed in order to
establish the policy of a Web service exchange (that is: the WSDLs for both the
explicit and implicit operations) via a single GetMetadata call.  With the
current solution, a client needs to get the 'main' WSDL via GetMetadata,
establish a list of the implicit operations, and then issue another GetMetadata
to get the implicit operation WSDL.

Side note: this highlights a problem that's already existing in the Metadata
spec: when multiple WSDL documents are returned from GetMetadata, how do we
distinguish the 'real' one - i.e. the one that would be returned from HTTP GET
targeted at <endpoint>?WSDL ?  We could address this problem under this issue
or under a new one.

3) I think that the spec may have already allowed for this behaviour(!!) and we
may have over-engineered the solution to 6721.  Therefore, we may inadvertently
have 2 solutions for the same problem, leading to potential interoperability
concerns.

Proposal :
----------

Explicitly state in the WS-MetadataExchange specification that the use of the
WSDL dialect combined with the appropriate identifier may be used in order to
acquire the WSDL(s) of any implicit operations.  

Remove the definitions of the dialect IRIs that we added to the individual
specs as part of 6721.


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Received on Tuesday, 13 October 2009 21:07:15 GMT

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