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RE: [rdfmsQnameUriMapping-6] CLOSED: Algorithm for creating a URI from a QName?

From: Dan Connolly <connolly@w3.org>
Date: Wed, 03 Dec 2003 09:19:24 -0600
To: "Williams, Stuart" <skw@hp.com>
Cc: "'ht@cogsci.ed.ac.uk'" <ht@cogsci.ed.ac.uk>, "Ian B. Jacobs" <ij@w3.org>, Jonathan Borden <jborden@mediaone.net>, www-tag@w3.org
Message-Id: <1070464764.19294.33.camel@dirk.dm93.org>

On Wed, 2003-12-03 at 08:24, Williams, Stuart wrote:

> Where I thought we landed was at the statement
> Ian quoted [4] from our minutes:
>   "The use of Qnames as identifiers without providing a mapping to 
>    URIs is inconsistent with Web Architecture." 

yes, quite.

> I don't believe a mapping to URI is necessary when a qname is being used to
> convey a qualified name! 

On the contrary: where we landed follows from web architecture
principle #1: The identification mechanism for the Web is the URI.

These are just principles; there are times and places to make
exceptions; but we discussed those and decided[4] they are
"inconsistent with Web Architecture".

Henry wrote:
> > Consider the QName 'a:b' in an XPath expression.  The XPath 
> > REC specifies carefully how to convert this to a 
> > URI/local-name pair, but it does _not_ specify a mapping to 
> > URIs, because it _can't_.  If the XPath expression concerned 
> > is, in its entirety
> > 
> >    "//*[@a:b]"
> > 
> > what could such a URI possibly be?

Doesn't the XML Schema component designators spec give
us a URI expansion for a:b? Hmm... perhaps that doesn't apply
to XPath.

Perhaps this is one of the exceptions, and whatever a:b
refers to, we cannot "link to it, make or refute assertions about it,
retrieve or cache a representation of it, include all or part of it by
reference into another representation, annotate it, or perform other
operations on it."
 -- http://www.w3.org/2001/tag/2003/webarch-20031128/#identification

> I believe that the TAGs intent is that where qnames are used as a means of
> identifying a Web Resource then there is a burden of the language designer
> to provide an explicit mapping between qnames used in the context of that
> language and URI that identify the same resource.

and that where qnames are not used as identifying a Web Resource,
that's outside of Web Architecture.

> Regards
> Stuart
> --
> [1] http://www.w3.org/2001/tag/doc/qnameids.html
> [2] http://www.w3.org/mid/1070385456.16926.79.camel@seabright
> [3] http://www.w3.org/2001/tag/doc/qnameids.html#sec-qnamesids
> [4] http://www.w3.org/2003/11/15-tag-summary.html#formats

Dan Connolly, W3C http://www.w3.org/People/Connolly/
Received on Wednesday, 3 December 2003 10:19:26 UTC

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