Querying XML Sources Using an Ontology-Based Mediator Bernd Amann, Catriel Beeri, Irini Fundulaki, and Michel Scholl   View Paper (PDF)   Return to Query Processing Abstract In this paper we propose a mediator architecture for the querying and integration of Web-accessible XML data sources. Our contributions are (i) the definition of a simple but expressive mapping language, following the local as view approach and describing XML resources as local views of some global schema, and (ii) efficient algorithms for rewriting user queries according to existing source descriptions. The approach has been validated by the STYX prototype. DiSC'03 © 2003 Association for Computing Machinery