W3C home > Mailing lists > Public > xmlschema-dev@w3.org > September 2006

RE: including a schema document multiple times

From: <noah_mendelsohn@us.ibm.com>
Date: Mon, 18 Sep 2006 18:35:38 -0400
To: "Michael Kay" <mike@saxonica.com>
Cc: "'Sandy Gao'" <sandygao@ca.ibm.com>, "'Wolfgang Jeltsch'" <wolfgang@jeltsch.net>, xmlschema-dev@w3.org
Message-ID: <OF67225621.420191CF-ON852571ED.007B9F8E-852571ED.007C1EA3@lotus.com>

Michael Kay writes: 

> (It doesn't even make it clear how you should absolutize the URI, 
> for example I've heard a serious suggestion recently that it's 
> incorrect to take xml:base into account.)

Sigh, yes.  Which is why my note of earlier this afternoon carefully said: 
"where two includes have schemaLocations with exactly the same 
URI".  A relative URI and an absolute URI are not the same URI, though 
they may "absolutize" to the same URI.  I was talking about the case where 
they were specified as character-by-character the same on the include.  I 
claim that case is fairly well covered.

The Recommendation says, as Sandy noted:

"Note: The above is carefully worded so that multiple <include>ing of the 
same schema document will not constitute a violation of clause 2 of Schema 
Properties Correct (3.15.6), but applications are allowed, indeed 
encouraged, to avoid <include>ing the same schema document more than once 
to forestall the necessity of establishing identity component by 
component."

Though a language lawyer could surely find lots of wiggle room, I don't 
think it's a great leap to suggest that this does cover the case where the 
exact same (character for character) URI appears on two includes.  To be 
clear, I'm not disagreeing that the wording is unfortunately vague, that 
there are important cases not covered, that it should if possible be 
improved, or that the rules for dealing with relative URIs aren't quite as 
clear as they might be.  I am saying that I think the intention in the 
case where the two URIs are really the same is clear enough.

--------------------------------------
Noah Mendelsohn 
IBM Corporation
One Rogers Street
Cambridge, MA 02142
1-617-693-4036
--------------------------------------








"Michael Kay" <mike@saxonica.com>
09/18/2006 05:52 PM
 
        To:     <noah_mendelsohn@us.ibm.com>
        cc:     "'Sandy Gao'" <sandygao@ca.ibm.com>, "'Wolfgang Jeltsch'" 
<wolfgang@jeltsch.net>, <xmlschema-dev@w3.org>
        Subject:        RE: including a schema document multiple times


> I haven't heard anyone question the intent of the section 
> quoted by Sandy in the common case where two includes have 
> schemaLocations with exactly the same URI. 

> Anyway:  I think there are important cases in which the 
> recommendation is quite clear. 

I agree that it's common sense to treat two includes on the same
(absolutized) URI as identical. I disagree that the Recommendation makes 
it
clear that you should do so. (It doesn't even make it clear how you should
absolutize the URI, for example I've heard a serious suggestion recently
that it's incorrect to take xml:base into account.)

Michael Kay
http://www.saxonica.com/
Received on Monday, 18 September 2006 22:35:57 GMT

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