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RE: Incompatibilities in RDQL implementations

From: Seaborne, Andy <andy.seaborne@hp.com>
Date: Thu, 6 May 2004 13:38:20 +0100
Message-ID: <E864E95CB35C1C46B72FEA0626A2E808031A8F9D@0-mail-br1.hpl.hp.com>
To: Jeremy Carroll <jjc@hplb.hpl.hp.com>, Jeen Broekstra <jeen@aduna.biz>, www-rdf-interest@w3.org
Cc: Arjohn Kampman <arjohn.kampman@aduna.biz>



-------- Original Message --------
> From: www-rdf-interest-request@w3.org <>
> Date: 6 May 2004 13:24
> 
> > Steve Harris wrote:
> > 
> > > On Thu, May 06, 2004 at 10:16:35 +0100, Phil Dawes wrote:
> > > 
> > > > SELECT ?family , ?given
> > > > WHERE  (?vcard  vcard:FN "John Smith")
> > > >       (?vcard  vcard:N  ?name)
> > > >       (?name   vcard:Family  ?family)
> > > >       (?name   vcard:Given  ?given)
> > > > USING  vcard FOR <http://www.w3.org/2001/vcard-rdf/3.0#>
> > > > 
> > > > 
> > > > Unfortunately both Sesame(1.0) and RAP(0.71) require '<' and '>'
> > > > around qnames for the query to parse.
> > > 
> > > 
> > > FWIW 3store requires both <>'s and commas, the commas thing is a
> > > bug and will be fixed. I'm be reluctant to remove or stop
> > > requireing the <>'s as I think it makes the queries more readable.
> > 
> > ObAOL: Ditto for Sesame.
> 
> What about the potential confusion between <vcard:Family> qname and
> <vcard:Family> new URI scheme?

I can't find the definition of the vcard: URI scheme just at the moment.

RDQL/Jena looks at <> things to see if there is such a prefix is defined.
If it is, then it's a qname-like thing and prefix/localname concatentation
is done; if not, its left as is.  So don't define a prefix of http:  :-)

This is all for compatibility with RDF with incorrect URIs in it and also
where databases have got scrambled by charset mismatches in the past.   The
use of <> on qnames allows quoting of characters ouside the grammar
production for qnames and then forcing the query to be read not as UTF-8.

	Andy

> 
> While I don't use RDQL much, I note that N3 has the same convention: <>
> indicate URI, no-<> indicates qname.
> 
> 
> 
> Jeremy
Received on Thursday, 6 May 2004 08:38:40 GMT

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