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Re: Fwd: I-D ACTION:draft-daigle-uri-std-00.txt

From: Michael Mealling <michael@bailey.dscga.com>
Date: Thu, 7 Sep 2000 11:29:45 -0400
To: John Aldridge <john.aldridge@informatix.co.uk>
Cc: michaelm@netsol.com, "Simon St.Laurent" <simonstl@simonstl.com>, xml-uri@w3.org
Message-ID: <20000907112945.B23109@bailey.dscga.com>
Comemnts below, I wnated to preserve the flow of the comments....

On Thu, Sep 07, 2000 at 04:14:59PM +0100, John Aldridge wrote:
> At 10:21 07/09/00 -0400, Michael Mealling wrote:
> >On Thu, Sep 07, 2000 at 02:51:39PM +0100, John Aldridge wrote:
> > > I'm quite happy with resources being a flexible, extensible concept.  I'm
> > > also happy with the name of a resource being a URI.  I understand, and I'm
> > > comfortable with the fact that the entity body associated with the 
> > resource
> > > may change from time to time; and that two distinct resources may, in 
> > fact,
> > > have the same associated entity body.
> > >
> > > What I'm not happy with is that there is no widespread agreement on how I
> > > tell whether two URIs name the same resource or not.
> >
> >There are really two answers to this and I'm afraid your not going to like
> >either of them:
> 
> On the contrary, I do like these answers...
> 
> >Resource: any abstract concept which is identified by a URI
> >URI:      a unique string that is bound in a 1:1 relationship with a Resource
> 
> >lexical equivalence: the act of comparing two URIs to see if they are
> >           syntactically identical and thus, by the first two definitions,
> >           identify the same Resource.
> 
> So, as I understand what you've said, two URIs identify the same resource 
> if those URIs are byte-for-byte identical.

Once you apply the canonicalization rules in RFC 2396, yes. You have
to do things like lower case domain-names, look at default port numbers, etc.
I know thats a pain but its not that hard to do.....

> I've snipped stuff which says that distinct resources may, in fact, be 
> functionally equivalent for various purposes.  Absolutely agreed.
> 
> Do you also agree with the following:
> 
> Do you go further and say that  XSLT (which matches elements and attributes 
> based on their namespaces being the same) must therefore use this 
> definition of equivalence?  I.e. two QNames match if their namespace URIs 
> are byte-for-byte identical and their local parts are the same?

I think this is dangerous ground because lexical equivalence of URIs
is a little more complciated that just byte-for-byte comparison. If you
do the correct canonicalization, then yes, byte for byte is correct. 
(now you have to realize that we're talking URIs here, not URI References
which is why I still support deprecating URI References for namespace names)

> Again, I agree, but Henrik Frystyk Nielsen (at least) has expressed the 
> view that this is not what the relevant RFCs/RECs say (or what they should 
> say).

Can you point me to that so I can see what he's saying? We may be using
different words and meaning the same thing....

-MM

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Received on Thursday, 7 September 2000 11:40:13 GMT

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