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RE: Action Item 2004-07-01 Solution to 168/R114

From: Martin Gudgin <mgudgin@microsoft.com>
Date: Tue, 13 Jul 2004 03:00:33 -0700
Message-ID: <DD35CC66F54D8248B6E04232892B633802B0462E@RED-MSG-43.redmond.corp.microsoft.com>
To: "David Booth" <dbooth@w3.org>, "Jeffrey Schlimmer" <jeffsch@windows.microsoft.com>
Cc: "Umit Yalcinalp" <umit.yalcinalp@oracle.com>, "WS Description List" <www-ws-desc@w3.org>


Let's take an interface with operations B and C both of which have the
same input message, X. Operation B has an output message Y, while
operation C has a different output message Z. Both B and C use the
In-Out pattern.  Whether you get message Y or Z back depends on the
content of X. Let's for the sake of argument say that if a particular
value in X is over 1000 you get Z, otherwise you get Y.

I believe that this is a coherent (if somewhat simplistic) example in
messaging systems. I also understand that it does not fit particularly
well into the RPC style. And that the WSDL does not describe the details
of how the server determines whether to send Y or Z. C'est la vie. There
is still enough information in the WSDL to construct messages that the
service will accept and to deconstruct messages the service will emit,
that is to interoperate with the service.

Some of you are wondering what happened to operation A. But that's
another story...

Gudge

> -----Original Message-----
> From: www-ws-desc-request@w3.org 
> [mailto:www-ws-desc-request@w3.org] On Behalf Of David Booth
> Sent: 08 July 2004 17:40
> To: Jeffrey Schlimmer
> Cc: Umit Yalcinalp; WS Description List
> Subject: RE: Action Item 2004-07-01 Solution to 168/R114
> 
> 
> At 02:30 PM 7/7/2004 -0700, Jeffrey Schlimmer wrote:
> 
> >WSDL 2.0 should not require identifying the operation name 
> because doing
> >so will unnecessarily limit the applicability of WSDL 2.0.
> 
> Can you give an example?
> 
> >R114 mandates that the WSD language define a way to uniquely 
> map, but it
> >does not mandate that each WSDL document must uniquely map.
> 
> The current wording of R114 is indeed ambiguous ("R114: The 
> description 
> language MUST allow unambiguously mapping any on-the-wire 
> Message to an 
> Operation.").  It isn't clear whether the "MUST allow" verb 
> applies to the 
> _mapping_ or the _writer_of_a_WSDL_document_, i.e., whether 
> it MUST allow 
> any message to be mapped to an operation (this would be the stronger 
> interpretation), or whether it MUST allow a WSDL document to 
> be written 
> such that any message can be mapped to an operation (this 
> would be the 
> weaker interpretation).  Also, the wording of this 
> requirement somehow 
> changed (weakened) after the WG agreed to it on 4 April 2002, 
> though I 
> can't find anything in the minutes to justify the change.  
> (Here is the 
> chronology that I found:
> http://lists.w3.org/Archives/Public/www-archive/2004Jul/0021.html )
> 
> However, I think the precise wording of R114 is somewhat 
> irrelevant.  The 
> real question is what does the WG think we need.
> 
> Jeffrey, are you suggesting that you think Scenario X (
> http://lists.w3.org/Archives/Public/www-ws-desc/2004Jun/0300.html )
> is an acceptable situation and is not a interoperability 
> problem that we 
> need to solve?
> 
> >The RPC style (http://www.w3.org/2004/03/wsdl/style/rpc) 
> defines a way
> >to uniquely map and therefore satisfies R114. Nothing else is needed.
> 
> Again, that depends on your interpretation of R114.  Unique GEDs also 
> provide a way to uniquely map.  Personally, I think the weak 
> interpretation 
> of R114 would render R114 somewhat pointless, because the 
> author of a WSD 
> can always simply write the WSD to use unique GEDs -- nothing 
> special is 
> needed in the WSDL 2.0 spec to facilitate this.
> 
> 
> -- 
> David Booth
> W3C Fellow / Hewlett-Packard
> Telephone: +1.617.253.1273
> 
> 
Received on Tuesday, 13 July 2004 06:01:05 GMT

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