This paper presents a system for efficient data transformations between XML and relational databases, called XML Data Mediator (XDM). XDM enables the transformation by externalizing the specification of the mapping in a script and using an efficient run-time engine that automates the conversion task. The runtime engine is independent from the mapping script. A parser converts a mapping script into an internal conversion object. For the mapping from relational to XML, we use a tagging tree as a conversion object inside the runtime engine, and use an SQL outer-join scheme to combine multiple SQL queries in order to reduce the number of backend relational database accesses. For the mapping from XML to relational, the conversion object is a shredding tree, and we use an innovative algorithm to process the XML as a stream in order to achieve linear complexity with respect to the size of the XML document. Categories and Subject Descriptors E.2 [Data Storage Representation] General Terms Alg...
Nianjun Zhou, George A. Mihaila, Dikran S. Melikse