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Re: Where does RDF fit in with XQuery?

From: Libby Miller <Libby.Miller@bristol.ac.uk>
Date: Fri, 22 Jun 2001 02:20:43 +0100 (BST)
To: Gary Zakon <gzakon@rcn.com>
cc: www-ql <www-ql@w3.org>, christop@ics.forth.gr
Message-ID: <Pine.GSO.4.21.0106220159040.809-100000@mail.ilrt.bris.ac.uk>

hi Gary

I think there are a few people working on the relationship between
Xquery and RDf query languages at the moment, among them Jonathan Robie
(XQuery) and Vassilis Christophides and others (RQL). I've been helping
Jonathan out with the RDF side of things.

Basically, because there are many different ways of serializing any
given RDF description of, say, a document in XML (see examples in the
RDF model and syntax - http://www.w3.org/TR/REC-rdf-syntax/), XQuery
isn't the easiest way to query RDF. A more straightforward way is to
query the underlying model, which is based on triples, regardless of the
exact syntax. This is what I've done with my prototype RDF query
language Squish, and what the RQL people have done in a rather more
finished way.

So it would be nice to query xml documents and the meta-information
about them in one format, but this looks difficult unless the RDF is in
some canonical format (there isn't one for RDF at least at the moment).

As regards schemas, I would think that XMLSchema would be more useful
for guidence on the sort of XQueries against XML documents that are
likely to be sucessful. RDF Schemas can perhaps help you with RDF
queries.

does that help at all?

RQL:
http://139.91.183.30:9090/RDF/RQL/

Squish:
http://swordfish.rdfweb.org/rdfquery/

RQL/Squish comparison demo
http://swordfish.rdfweb.org/discovery/2001/06/squishtests/

Libby


On Thu, 21 Jun 2001, Gary Zakon wrote:

> Hi,
> 
> I'm struggling a bit with understanding the role of RDF and its relationship
> to XML Schema and now XQuery.  Any help anyone can offer to clarify things a
> bit is much appreciated.
> 
> What role (if any) does RDF play with respect to XQuery?  XQuery allows me
> to query across multiple XML documents.  If those documents are described
> using RDF does that help me formulate my queries in any way?  For example,
> RDF can inform me of the relationships between different XML documents.  Or
> is the XML Schema for those documents more relevant?  Or are they both
> relevant?
> 
> Thanks,
> 
> Gary
> 
> 
Received on Thursday, 21 June 2001 21:21:14 GMT

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