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RDF Use Cases

From: Jonathan Robie <jonathan.robie@datadirect-technologies.com>
Date: Wed, 18 Sep 2002 17:29:30 -0400
Message-Id: <5.1.0.14.0.20020918172432.016b5e48@mail.verizon.net>
To: public-qt-comments@w3.org, www-xml-query-comments@w3.org, libby.miller@bristol.ac.uk, dan@w3.org, emiller@w3.org, www-rdf-interest@w3.org

This is a response to Libby Miller's comment [1] on RDF query use
cases. These use cases were very helpful in determining how XQuery
might be used on RDF data. In fact, Libby and I were two of the
authors of a paper originally presented at Extreme Markup, then
published in Markup Technologies in a modified form [2].

The most important lessons learned from this paper are:

1. XQuery works fine on RDF or topic maps, but the variety of
syntactic forms for these languages means that datasets must be
normalized either before or after the query, or else more complex
queries must be written to take into account all possible syntactic
representations. Normalization is not particularly difficult, and the
normalizations can also be written in XQuery.

2. Some normalized forms are easier to query than others. For RDF,
merged descriptions were the easiest to query efficiently.

3. XQuery was able to perform the same queries as the special-purpose
query languages, and the resulting queries were not particularly more
complex.

4. The approach we took does not preserve as much RDF or Topic Map
type information as special purpose languages for querying these
sources. A library that does preserve more information is probably
possible, but this work has not been done.

Jonathan Robie
On behalf of the XML Query Working Group

[1] 
http://lists.w3.org/Archives/Public/www-xml-query-comments/2001Jun/0007.html
[2] http://www.w3.org/XML/2002/08/robie.syntacticweb.html
Received on Wednesday, 18 September 2002 17:30:06 GMT

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