W3C home > Mailing lists > Public > xmlschema-dev@w3.org > September 2002

Re: How to reference attributes from list items

From: <noah_mendelsohn@us.ibm.com>
Date: Mon, 9 Sep 2002 14:03:30 -0400
To: "Eric Jain" <Eric.Jain@isb-sib.ch>
Cc: "xmlschema-dev" <xmlschema-dev@w3.org>
Message-ID: <OFD3CA2F2F.A2BAAE27-ON85256C2F.0062621A@lotus.com>

Eric Jain writes:

>> I guess in order to express co-occurrence
>> constraints in a general way you would 
>> need some kind of if-then-else constructs. 

Or something schematron-like based on some combination of fuller XPath, 
XSLT, etc.  I'd really like to make sure if we go that way that the 
possibilities for optimized performance are in then same range as what we 
have today, that streaming is no worse than what you'd expect 
(co-occurrence always involves keeping a bit of data aside to deal with 
forward references, but what we have today is essentially just the key 
data, and is completely predictable as you first encounter the instance 
data), and I'd really prefer to have all constraints as part of the type 
system.  Anyway, it's something that would take some serious design work 
to get right.  Other than my concerns about the risks of complicating an 
already complex language, I do hope we get to it.  I think it's the most 
consistent requirement we hear from users, at least as to a missing 
feature.  Thanks.

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Noah Mendelsohn                              Voice: 1-617-693-4036
IBM Corporation                                Fax: 1-617-693-8676
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Received on Monday, 9 September 2002 14:05:00 GMT

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