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Re: RDF Issue rdfms-uri-substructure

From: Jan Grant <Jan.Grant@bristol.ac.uk>
Date: Mon, 18 Feb 2002 17:30:42 +0000 (GMT)
To: Brian McBride <bwm@hplb.hpl.hp.com>
cc: www-rdf-comments@w3.org
Message-ID: <Pine.GSO.4.44.0202181727080.15622-100000@mail.ilrt.bris.ac.uk>
On Mon, 18 Feb 2002, Brian McBride wrote:

> Jan,
>
> In
>
>    http://lists.w3.org/Archives/Public/www-rdf-interest/2000Jul/0037.html
>
> you raised an issue which was captured in
>
>    http://www.w3.org/2000/03/rdf-tracking/#rdfms-uri-substructure
>
> as
>
> [[[
> "an xmlns-qualified name is a pair of (namespace URI, name); there is no
> composition function implied apart from the trivial 'shove both bits into a
> pair'. But RDF claims that resources are (or are identified by) URIs only;
> there seems to be an (implicit? explicit?) composition function that takes
> the namespace and the name part and produces a URI from them."
> ]]]
>
> As recorded in
>
>    http://lists.w3.org/Archives/Public/w3c-rdfcore-wg/2002Feb/0476.html
>
> the RDFCore WG has:
>
>    resolved to close this issue on the grounds
>    that changing how resources are named on the
>    web is a web architecture issue and beyond
>    the scope of our charter.
>
> Further:
>
> Whereas:
>
> (a) the RDF 1.0 spec says that property and class names
> are computed from element and attribute names
> by concatenating their namespace names with their local names
>
> (b) it's useuful to be able to process RDF with
> XPath and XSLT, where even though
>          concat(namespace-name(qname1), local-name(qname1))
> is the same as
>          concat(namespace-name(qname2), local-name(qname2))
> the qnames themselves may not compare equal in XPath expressions.
>
> (c) lots of implementors have looked for advice on how to serialize RDF,
> and, in particular, how to compute a namespace name and localname from the
> name of a property or a class.  the WG advises RDF
> schema/namespace/vocabulary designers
>
> (d) choose namespace names that end in non-xml-name-characters such as / # ?
>
> and we advise implementors of RDF serializers:
>
> (e) in order to break a URI into a namespace name and a local name, split
> it after the last XML non-name character.  If the URI ends in a
> non-name-character throw a "this graph cannot be serialized in RDF 1.0"
> exception.
>
> Please could you respond to this message, copying www-rdf-comments@w3.org
> indicating whether this is an acceptable resolution of this issue.

That's fine; my original message just captured some of the confusion
that I (and others I'd spoken to) had expressed at the time. WRT point
(e) above, it's worthwhile pointing out [well, I couldn't figure it out]
that the place where being unable to split a URI into
(namespace,localname) bites you is for property names, since subjects
and objects can be encoded using rdf:about and rdf:resource.

Many thanks to the rdfcore group who are doing a sterling job! :-)

jan

-- 
jan grant, ILRT, University of Bristol. http://www.ilrt.bris.ac.uk/
Tel +44(0)117 9287088 Fax +44 (0)117 9287112 RFC822 jan.grant@bris.ac.uk
"I like oranges more than apples!?" - that's like comparing apples and oranges!
Received on Monday, 18 February 2002 12:33:18 GMT

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