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[Bug 5289] "##defined" in wildcards

From: <bugzilla@wiggum.w3.org>
Date: Fri, 07 Dec 2007 09:14:38 +0000
To: www-xml-schema-comments@w3.org
Message-Id: <E1J0ZI6-0001Ka-AO@wiggum.w3.org>


------- Comment #2 from mike@saxonica.com  2007-12-07 09:14 -------
Noah, your comment seems to be making some technical arguments, but it is
mostly a "point of order" that suggests the issue should not be opened because
it has already been adequately discussed. 

I'm in the slightly ambiguous position here in that I'm a member of the working
group, but I wasn't a member at the time of those discussions. But I don't
think I would feel inhibited from making this comment even if I had initially
been the leading exponent or opponent of the current feature.

My experience of standards work is that you always get a better standard if it
is informed by implementation experience, and that implementing a specification
always yields new insights that were not available when the feature was
initially discussed "in a vacuum". My understanding of the last call process is
that it is there to encourage people to start implementing the specification
and to report their experiences, and I do not think there are any process
grounds for rejecting such feedback.

As for the technical point, I'm not sure I understand your remark that we don't
talk about "adding an element" to a schema. It's true that we don't have a very
well articulated model of schema construction, but we do explicitly say that
the process can be incremental, and that you can use some definitions in the
schema before all definitions are available. All my comment is doing is to
point out that the new ##defined facility adds further implementation
complexity to the process of incremental schema construction.

I also think that we should give more thought to the XML database scenario.
This isn't my scenario as an implementor, but I do come across it as a user and
as a consultant. There are a number of different ways that an XML database can
implement the concept of "a schema", but in most of them, schemas as well as
instances are likely to be long-lived, and to change over time. It sems to me
that action-at-a-distance facilities like ##defined make it more difficult to
ensure that when changes are made to a schema, they are being made in a
backward-compatible way, that is, to guarantee that all existing instances will
remain valid. 
Received on Friday, 7 December 2007 09:14:45 UTC

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