With currently available tools and languages, translating between an existing XML format and RDF is a tedious and error-prone task. The importance of this problem is acknowledged by the W3C GRDDL working group who faces the issue of extracting RDF data out of existing HTML or XML files, as well as by the Web service community around SAWSDL, who need to perform lowering and lifting between RDF data from a semantic client and XML messages for a Web service. However, at the moment, both these groups rely solely on XSLT transformations between RDF/XML and the respective other XML format at hand. We propose a more natural approach for such transformations based on merging XQuery and SPARQL into the novel language XSPARQL.

Recently, two new languages have entered the stage for processing XML and RDF data: XQuery is a W3C Recommendation since early last year and SPARQL has finally received W3C's Recommendation stamp in January 2008. While both languages operate in their own worlds - SPARQL in the RDF- and XQuery in the XML-world - we show in this specification that the merge of both in the novel language XSPARQL has the potential to finally bring XML and RDF closer together. XSPARQL provides concise and intuitive solutions for mapping between XML and RDF in either direction, addressing both the use cases of GRDDL and SAWSDL. As a side effect, XSPARQL may also be used for RDF to RDF transformations beyond the capabilities of "pure" SPARQL. We also describe an implementation of XSPARQL, available for user evaluation.


Any inquiries should be directed to: Axel Polleres or Nuno Lopes from DERI Galway at the National University of Ireland, Galway, Ireland (axel.polleres@deri.org, nuno.lopes@deri.org).