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RE: LC124

From: <paul.downey@bt.com>
Date: Thu, 7 Jul 2005 12:24:40 +0100
Message-ID: <2B7789AAED12954AAD214AEAC13ACCEF2709E4A8@i2km02-ukbr.domain1.systemhost.net>
To: <ryman@ca.ibm.com>, <www-ws-desc@w3.org>


thanks for taking the time and trouble to discuss this issue 
and in trying to gain a company position within IBM. 

I'll try and answer the discussion points raised:

1) Agreed, obviously! Enabling the description of Web 
   services that evolve is likely to be our top reason to 
   move towards using WSDL 2.0. 

2) Agreed, in essence this is an XML Schema issue, hence our 
   original efforts to engage the Schema WG in a joint Task Force 
   for versioning. However, Web services has a strong and simple 
   use case for evolution of messages and much of the current focus 
   of work on versioning within XML Schema has been in gathering 
   other use-cases targeted at XML Schema 1.1

   The cautionary tale regarding SOAP encoding is a good example, 
   however that was a far more radical change than this proposal
   and predated the XML Schema Recommendation.
   ignoreUnkowns allows continued use of a current schema processor 
   for validation, whilst embodying current best practice exhibited 
   by the more flexible data binding implementations.

3) This is an interesting point, but one which does fall into the 
   semantics of the additional content:

   If a processor requires the additional content, or that additional
   content changes the meaning of existing content, then it isn't
   a backwards compatible change, and should be published as a new
   message, operation, service, etc.

   The boolean flag enables publishers to add and accept additional
   content, or highlight that strict validation should be used to 
   constrain the message contents. I'm not sure what more information
   would be useful, without exposing 'semantics', something
   we avoid in WSDL.

4) Please see the latest proposals for text:


-----Original Message-----
From: www-ws-desc-request@w3.org [mailto:www-ws-desc-request@w3.org]On Behalf Of Arthur Ryman
Sent: 06 July 2005 23:33
To: www-ws-desc@w3.org
Subject: LC124

I've been discussing LC124 with my colleagues and I thought I'd post an update in case we discuss this tomorrow. 

1. In general, we agree the versioning is important, and we'd like the problem addressed. 
2. We are concerned that this is really an XML Schema problem and that WSDL is probably not the right place to address it. There is work going on now in the Schema WG. There are several solutions being proposed and it would be premature for WSDL to adopt the validate-twice solution (although that is a strong contender). As a cautionary tale, the creative use of Schema with SOAP Encoding was cited. The schema didn't really describe the message. We don't want a repeat in WSDL 2.0. We are concerned about locking in a solution that may not agree with the direction of Schema. 
3. The boolean nature of ignoreUnknowns is not very useful. In many scenarios, it is important to know if the unknown content is preserved (e.g. passed on) or even processed. 
4. There is no normative document that describes the proposed processing algorithm. Who will write that? (pointing to conference papers is not adequate). The WSDL spec should only cite other specs for Core features. 

I need more time to establish a company position since this is vacation season. I'll try to move this issue forward though. 

Arthur Ryman,
Rational Desktop Tools Development

phone: +1-905-413-3077, TL 969-3077
assistant: +1-905-413-2411, TL 969-2411
fax: +1-905-413-4920, TL 969-4920
mobile: +1-416-939-5063, text: 4169395063@fido.ca
intranet: http://labweb.torolab.ibm.com/DRY6/
Received on Thursday, 7 July 2005 11:25:25 UTC

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