The proliferation of XML as a standard for data representation and exchange in diverse, next-generation Web applications has created an emphatic need for effective XML data-integration tools. For several real-life scenarios, such XML data integration needs to be DTD-directed – in other words, the target, integrated XML database must conform to a prespecified, user- or application-defined DTD. In this paper, we propose a novel formalism, XML Integration Grammars (XIGs), for specifying DTD-directed inn of XML data. Abstractly, an XIG maps data from multiple XML sources to a target XML document that conforms to a predefined DTD. An XIG extracts source XML data via queries expressed in a fragment of XQuery, and controls target document generation with tree-valued attributes and the target DTD. The novelty of XIGs consists in not only their automatic support for DTD-conformance but also in their composability: an XIG may embed local and remote XIGs in its definition, and invoke these...
Wenfei Fan, Minos N. Garofalakis, Ming Xiong, Xibe