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Re: An analysis of mustUnderstand and related issues

From: <Noah_Mendelsohn@lotus.com>
Date: Tue, 15 May 2001 11:13:53 -0400
To: Mark Jones <jones@research.att.com>
Cc: moreau@crf.canon.fr, xml-dist-app@w3.org
Message-ID: <OFBE161760.86567A91-ON85256A4D.004FC341@lotus.com>
Mark Jones writes:

>> I also wondered about disjunction. 

I agree, it's potentially useful.  I think the overall XML experience 
teaches us to be very reluctant about adding complexity, even if the 
function provided seems "useful".  Indeed, the most obvious criticism of 
my proposal as it stands is that even the function it does provide has not 
been shown to meet that 80/20 or value/simplicity cut.  The concern I have 
about the additional complexity of supporting disjunctions is that it 
rapidly leads to at least predicate logic, and maybe a full programming 
language.  Can I do a full:

        <SOAP-ENV: Header SOAP-ENV:dependsOn="( (AND (OR A B C )  D  (OR E 
F)))"/>  ?

(and yes, we would probably want to use full markup, as you suggest).  Do 
we allow full Turing-complete computation? 

Now, that's not necessarily a bad thing, but it's significantly more 
complexity in SOAP processors, harder to write tools that reason about 
what's happening, etc., harder for users to grok, etc.  Also:  at some 
point you want to tie this stuff into higher level flow management systems 
such as WSFL [1]. 

So, my recommendation is that we do indeed consider the proposal for 
disjunctions, but that we set the bar reasonably high on actually agreeing 
to mandate it.  Thank you.

[1]  http://www-4.ibm.com/software/solutions/webservices/pdf/WSFL.pdf

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Noah Mendelsohn                                    Voice: 1-617-693-4036
Lotus Development Corp.                            Fax: 1-617-693-8676
One Rogers Street
Cambridge, MA 02142
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Received on Tuesday, 15 May 2001 11:17:37 GMT

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