Object-Oriented mediator queries to XML data

The mediator/wrapper approach is used to integrate data from different databases and other data sources by introducing a middleware virtual database that provides high level abstractions of the integrated data. A framework is presented for querying XML data through such an Object-Oriented (OO) mediator system using an OO query language. The mediator architecture provides the possibility to specify OO queries and views over combinations of data from XML documents, relational databases, and other data sources. In this way interoperability of XML documents and other data sources is provided. The mediator provides OO views of the XML data by inferring the schema of imported XML data from the DTD of the XML documents, if available, using a set of translation rules. A strategy is used for minimizing the number of types (classes) generated in order to simplify the querying. If XML documents not having DTDs are read, or if the DTD is incomplete, the system incrementally infers the OO schema from the XML structure while reading XML data. This requires that the mediator database is capable of dynamically extending and modifying the OO schema. The paper overviews the architecture of the system and describes incremental rules for translating XML documents to OO database structures.