- From: Jonathan Robie <jonathan.robie@datadirect-technologies.com>
- Date: Wed, 18 Sep 2002 17:30:07 -0400 (EDT)
- 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 Thursday, 19 September 2002 04:22:32 UTC