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RE: [Fwd: xmlns, uri+name pairs or just uris..? Clarification n eeded.]

From: McBride, Brian <bwm@hplb.hpl.hp.com>
Date: Mon, 31 Jul 2000 20:33:24 +0100
Message-ID: <5E13A1874524D411A876006008CD059F239328@0-mail-1.hpl.hp.com>
To: "'Graham Klyne'" <GK@Dial.pipex.com>, caro@Adobe.COM
Cc: RDF-list <www-rdf-interest@w3.org>
Hi Graham,

> It seems to me that the requirement to find the 
> namespace-related 
> portion of a URI in isolation is not reasonable.  It's also 
> not clear to me 
> what purpose it serves.

SiRPAC's java API only ever passes through the full URI - it
never passes through the URI split into the namespace part 
and the rest.  If an RDF processor wishes to determine what
schema applies, perhaps to do validation or schema directed
editing, it needs to be able to figure out the right namespace.
So either the java api needs to change or there needs to be
a way to figure out the namespace.  I guess I'm uncomfortable
with Dan's suggestion of the parser adding statements to the
model - not its job to modify the model it is given really.

Further, independent of the API, there are situations when it would be 
helpful for an RDF processor to be able to determine the
namespace of a resource from its URI, e.g. when it encounters
a subPropertyOf property in a schema.  The processor may well
wish to determine the schema of the super property, e.g. to 
determine domain and range constraints.

Brian McBride

> At 11:41 AM 7/28/00 -0700, Perry A. Caro wrote:
> >Gerard Maas wrote:
> >
> > > > I have seen '/' as well. If I'm not mistaken, the 
> rdf-api assumes either
> > > > a "#" or a "/" separating the namespace from the local name.
> >
> >Ouch.  What about the class of schema URIs that use ":" as a 
> separator?
> >URNs, for example?
> >
> >For any RDF processor that uses concatanation for expanded 
> names, I would
> >recommend the following best practice:  When an expanded 
> name needs to be
> >decomposed into its namespace and local parts, take the URI 
> and do a reverse
> >scan, character by character, from the end of the string, 
> until a character
> >is found that is not legal as an XML name, OR until a colon 
> ":" is found.
> >The last clause is necessary because ":" is legal in XML names.
> >This practice broadens the field of well-formed RDF that 
> processors will
> >accept.  Why rule out "+" or "?" or "="?
> >
> >It would also be nice if the RDF Schema spec made a VERY STRONG
> >recommendation that namespace URIs for RDF end in either "#" 
> or "/". That,
> >with the addition of ":", is what our internal namespace guidelines
> >recommend.
> >
> >Perry
> ------------
> Graham Klyne
Received on Monday, 31 July 2000 15:33:59 UTC

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