W3C home > Mailing lists > Public > xmlschema-dev@w3.org > March 2004

Re: pervasiveness of a redefine

From: Henry S. Thompson <ht@inf.ed.ac.uk>
Date: Tue, 30 Mar 2004 08:54:54 +0100
To: noah_mendelsohn@us.ibm.com
Cc: "'James Taylor'" <JTaylor@nextance.com>, "Michael Kay" <mhk@mhk.me.uk>, xmlschema-dev@w3.org, www-xml-schema-comments@w3.org
Message-ID: <f5b8yhiu5v5.fsf@erasmus.inf.ed.ac.uk>

noah_mendelsohn@us.ibm.com writes:

> It is not an error for the ·actual value· of the schemaLocation 
> [attribute] to fail to resolve it all, in which case no corresponding 
> inclusion is performed. It is an error for it to resolve but the rest of 
> clause 1 above to fail to be satisfied. Failure to resolve may well cause 
> less than complete ·assessment· outcomes, of course. "
>
> My reading is that this comes mighty close to being a roundabout way of 
> saying it's a hint, as you can always claim that you were just 
> sufficiently disconnected from the web that this or that URI didn't 
> resolve.  I would have preferred to say "it's an error for the 
> schemaLocation of an include not to resolve."

My _dim_ memory was that this was in the spirit of our "no use, no
error" policy wrt missing declarations and definitions in general.  On
balance, I still think it's correct.

> I am actually surprised to find that <redefine> is yet different, since I 
> thought we had intended it to be completely parallel to include.  It is in 
> most respects, but the second part of the quote above is not repeated for 
> redefine.  Unless I'm missing something, we are silent on the implications 
> of failure of schemaLocation to resolve for redefine.   Since we went to 
> such trouble to say that it's not an error for <include> and not to say 
> for the very similar <redefine>, one can almost make the case that the URI 
> MUST resolve for <redefine>.  On the other hand, we don't quite say so.

Again, I think that's right (not the unclarity, the error).  With
redefine, a failure to resolve means _wrong_ definitions, not missing
ones, and this may be the only chance to signal the failure.

> At the very least, I think we should clarify the rules for redefine. 

Yes.

> Henry, if you agree, I think one of us should send a note to the comments 
> list openning an issue.

This message CC'ed to the issues list for that purpose.

ht
-- 
 Henry S. Thompson, HCRC Language Technology Group, University of Edinburgh
                     Half-time member of W3C Team
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                   URL: http://www.ltg.ed.ac.uk/~ht/
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Received on Tuesday, 30 March 2004 02:55:47 UTC

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