Federating heterogeneous data sources with XML

XML has emerged as the leading language for representing and exchanging data either on the Web or in the enterprise for general purposes. Although XQuery is emerging as the standard for XML query languages, tools are still needed to mediate between XML queries and heterogeneous data sources for the integration of data in XML. This paper presents the XLive mediator, a unique tool for integrating and querying disparate heterogeneous information as unified XML views. It describes the mediator architecture and focuses on the unique distributed query processing technology implemented in this component. Query evaluation is based on an original XML algebra simply extending classical operators to process tuples of tree elements. Further, we present a set of performance evaluation on a relational benchmark, which leads to discuss possible performance enhancements