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WSDL "service references" and WSA endpoint references

From: Jonathan Marsh <jmarsh@microsoft.com>
Date: Wed, 27 Apr 2005 17:08:52 -0700
Message-ID: <7DA77BF2392448449D094BCEF67569A50756A142@RED-MSG-30.redmond.corp.microsoft.com>
To: <public-ws-addressing@w3.org>

At the recent WSDL FTF, we discussed issue LC117 [1] which is about
"service references".  WSDL 2.0 doesn't define a specific construct in
the WSDL Core spec, but instead provide a wsdl:ServiceType in our schema
from which <wsdl:service> is derived.  In the primer [2] we show how an
application can define structures derived from wsdl:ServiceType that
serve as references to a Web service.  The scenario this attempts to
satisfy is describing a Web service that refers the client to another
Web service, by indicating the address and type (interface and or
binding) the referenced service implements.

It has become apparent that our current solution has drawbacks - namely
that XML Schema limits one's ability to describe the service reference
by fixing certain values (interface and binding) of children elements in
the WSDL namespace.  This is causing us to reevaluate the current
design, and to revisit previous proposals to provide a separate XML
construct for service references.

We noted the similarity of endpoint references and service references,
and many felt there may be some opportunities for convergence or
harmonization.  However, it appears that the same limitation in our
service references applies to wsa:EndpointReferences - namely, how can
one use XML Schema to derive from the wsa:EndpointReferenceType, fixing
the allowed values of wsa:Metadata/wsaw:ServiceName or
wsa:Metadata/wsaw:InterfaceName?

We would like the WS-A WG to:
1) review the service reference topic of the primer [2],
2) examine the relationship of service references to endpoint 
   references, and
3) examine the problem of describing an EPR with certain fixed values 
   using XML Schema.

- Jonathan Marsh on behalf of the WSDL WG.

[1] http://www.w3.org/2002/ws/desc/4/lc-issues/issues.html#LC117
[2]
http://dev.w3.org/cvsweb/~checkout~/2002/ws/desc/wsdl20/wsdl20-primer.ht
ml#adv-service-references
Received on Thursday, 28 April 2005 00:10:09 GMT

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