Re: RDF Issue rdfms-uri-substructure

On Mon, 18 Feb 2002, Brian McBride wrote:

> Jan,
> In
> you raised an issue which was captured in
> 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
> 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
> 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 grant, ILRT, University of Bristol.
Tel +44(0)117 9287088 Fax +44 (0)117 9287112 RFC822
"I like oranges more than apples!?" - that's like comparing apples and oranges!

Received on Monday, 18 February 2002 12:33:18 UTC