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RE: Proposed XQuery requirement and/or objective

From: Rob Shearer <Rob.Shearer@networkinference.com>
Date: Tue, 20 Jul 2004 10:42:48 -0700
Message-ID: <CFE388CECDDB1E43AB1F60136BEB497302810A@rome.ad.networkinference.com>
To: "Howard Katz" <howardk@fatdog.com>, "Steve Harris" <S.W.Harris@ecs.soton.ac.uk>, <public-rdf-dawg@w3.org>

As usual, Howard's analysis is entirely correct. (And I meant to use //,
not /, just as he points out.)

The idea is that 'asserted()' is in fact an external function; in the
simplest case we're assuming the RDF data is just sitting in the context
somehow, not necessarily accessible in any way other than these external
functions.

> -----Original Message-----
> From: Howard Katz [mailto:howardk@fatdog.com] 
> Sent: Tuesday, July 20, 2004 10:20 AM
> To: Rob Shearer; Steve Harris; public-rdf-dawg@w3.org
> Subject: RE: Proposed XQuery requirement and/or objective
> 
> Steve,
> 
> Just to clarify Rob's example a bit (you don't mind, do you, Rob?):
> 
> 1) Rob's using an XML document with one or more <Person> 
> elements in it. It
> looks like this could be any sort of XML document, not necessarily an
> RDF/XML serialization. (Is that correct, Rob?)
> 
> 1) His use of "doc(http://foo/people.xml)/Person" implies a 
> single document
> with a single <Person> as the root element. Since that's not 
> very useful,
> it's more likely he meant to say:
> 
>     doc( http://foo/people.xml" )//Person
> 
> which implies that the document has mulitple <Person> 
> elements in it, the
> more likely scenario; the descendant operator (//) then 
> dereferences off the
> single document node returned by doc() and grabs all its 
> <Person> elements
> at one fell swoop.
> 
> 2) If it's straightforward XML and didn't have any xmlns: namespace
> declaration against <Person>, you don't need a namespace 
> prefix to retrieve
> it via XPath.
> 
> 3) Whether the step operator is "/" or "//", neither usage implies an
> rdf:type. Rob's working in XML and he's getting XML <Person> 
> elements back,
> not RDF.
> 
> Rob:
> Just to clarify something, when you say:
> 
>     asserted( $member/URI, ...#worksFor, ...#NetworkInference )
> 
> is asserted() an external function (ie, one that's allowed to 
> manipulate
> *anything*, not necessarily just items that are in the XQuery 
> data model)
> that has access to an actual RDF graph or graphs and is doing 
> "real" RDF
> querying against their triples directly? That would make 
> sense to me if so.
> 
> Howard
> 
> > -----Original Message-----
> > From: public-rdf-dawg-request@w3.org
> > [mailto:public-rdf-dawg-request@w3.org]On Behalf Of Rob Shearer
> > Sent: Tuesday, July 20, 2004 9:18 AM
> > To: Steve Harris; public-rdf-dawg@w3.org
> > Subject: RE: Proposed XQuery requirement and/or objective
> >
> >
> >
> > > > for $member in doc(http://foo/people.xml)/Person
> > > > where asserted($member/URI, http://foo#worksFor,
> > > http://foo#NetworkInference)
> > > > return $member/name
> > >
> > > Wouldn't "Person" in the first line require some
> > > namespace/prefix? Also, I
> > > dont quite understand why the / after doc() implies the
> > > rdf:type part of the
> > > 	($memeber  rdf:type  foo:Person)
> > > triple. Is it just shorthand? if so, why "/"?
> >
> > No; this example was meant to demonstrate use of XML along with RDF
> > stuff, so the XPath expression was just selecting all the top-level
> > <Person> elements in some XML doc in the conventional way. 
> Everything
> > but the asserted() call is vanilla XQuery.
> >
> 
> 
Received on Tuesday, 20 July 2004 13:45:07 GMT

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