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Re: A new proposal (was: Re: which layer for URI processing?)

From: John Cowan <jcowan@reutershealth.com>
Date: Fri, 26 May 2000 13:45:23 -0400
Message-ID: <392EB833.FE80F255@reutershealth.com>
To: Jonathan Borden <jborden@mediaone.net>, "xml-uri@w3.org" <xml-uri@w3.org>
Jonathan Borden wrote:

>         No, I am asking what the precise definition of equivalence is. If you allow
> me to define u1 = u2 (literal comparison) and R1 equivalent R2, by
> definition, even for relative URIs then problem solved.

There are no "relative URIs".  There are relative URI references, but
string-equality for URI references is neither necessary nor sufficient
to make the URI references identify the same resource.

If the URI references are string-equal and so are the base URIs, then
the resources identified are the same, but this is not a necessary
condition.

> What if the provider of the resource doesn't have a clue (as is literally
> true if you care to poll a number of real website providers :-)

*shrug*.  If I ask you whether your (imaginary) book "XML Without Tears"
is the same as your other book "Learning XML While Standing On One Foot", is
it really probable that you won't have a clue about it?

Hardly.  You will say, "No, they are different books", or "Yes, they are the same
book but with different titles in the U.S. and the U.K." or something like this.
 
>         Do we agree on this? If this is true for relative URIs then you agree that
> there is no problem with the current Namespace rec, clase closed.

It would be if there were any relative URIs, but there aren't.  :-)
 
>         You are missing my point. I am arguing to keep the current Namespace rec as
> specified. The "problem" which exists is not unique to relative URIs but
> also for "absolute" URIs (e.g. "file" "news" "http"?) which are context
> dependent.

The problem (from the TimBL camp's viewpoint) is not that some URI references are
context-dependent, but that the Namespace Rec defines a version of equality
between pairs of URI references that conflicts with the rest of the Web
system's understanding of equality.

>         Banning relative URIs, or 'absolutizing' them (quotes because prepending
> the base URI which itself may be a file URI doesn't cut it) doesn't solve
> the problem of context dependency.

"Absolutizing" is a term of art, equivalent to "RFC 2396 resolution".

-- 

Schlingt dreifach einen Kreis um dies! || John Cowan <jcowan@reutershealth.com>
Schliesst euer Aug vor heiliger Schau,  || http://www.reutershealth.com
Denn er genoss vom Honig-Tau,           || http://www.ccil.org/~cowan
Und trank die Milch vom Paradies.            -- Coleridge (tr. Politzer)
Received on Friday, 26 May 2000 13:46:25 UTC

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