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Proposed Resolution: Issue 294 - "message exchange context out of nowhere?"

From: Marc Hadley <marc.hadley@sun.com>
Date: Fri, 18 Oct 2002 14:16:26 -0400
To: xml-dist-app@w3.org
Message-Id: <B728AE66-E2C5-11D6-9506-0003937568DC@sun.com>

Issue 294 concerns problems with the notion of a message exchange 
context. In particular it notes that:

"The notion of Message Exchange Context (MEC) is central to the
Binding Framework. However:

    (i) No formal definition for it is given in the glossary. There
      is only a vague description for it in part 2, section 5.1.2.
    (ii) No real indication is given as to how a MEC is initialized
      or, possibly, transferred. For example, how does a SOAP node
      determine it should instantiate
      "context:ExchangePatternName" to
      "http://www.w3.org/2002/06/soap/mep/request-response/" and
      not to something else? IMO, part 2 should be explicit,
      either saying this is implementation specific, or providing
      a standard means for indicating, for example, the features
      being used."

Point (i)
I agree with the concern expressed, the notion of an MEC is only 
introduced loosely within the text. However part 2 contains no glossary 
and as MECs are only mentioned in part 2 it would seem strange to add 
this to the part 1 glossary. To fix point (i) I recommend that section 
5.1.2 be restructured to contain subsections for Message Exchange 
Context and Environment containing tighter definitions of the two terms.

Point (ii)
Instantiation of an MEC for the Request-Response and SOAP Response MEPs 
is covered in sections 6.2.3 and 6.3.3 respectively for both requesting 
and receiving SOAP nodes. At the abstract level I think this is 
sufficient well specified. However I agree with the originator of the 
issue that bindings need to spell out how this information is 
transferred and I don't think the current HTTP binding does this 
explicitly for the MEP identifier at the moment (the other properties 
are covered however. To fix point (ii) I recommend that text be added 
to section 7.5 to describe how the binding exchanges/determines the 
value of context:ExchangePatternName (presumably using the HTTP method: 
GET==SOAP Response, POST==Request-Response ?).

Regards,
Marc.

--
Marc Hadley <marc.hadley@sun.com>
XML Technology Center, Sun Microsystems.
Received on Friday, 18 October 2002 14:16:50 GMT

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