XML-based data integration

Today’s fast and continuous growth of large business organizations enforces an increasing need in integrating and sharing large amounts of data, coming from a number of heterogeneous and distributed data sources. Thus, during the last decade, research and business community interest has migrated from DataBase Management Systems (DBMS) to data integration systems. Whereas the former make a unique local data source accessible through a schema, the latter offer the necessary framework to combine the data from a set of heterogeneous and autonomous sources through a socalled global schema. We call such a system a hierarchical data integration system. Today, one more step is being achieved towards so-called Peer-to-Peer (P2P) data integration systems, which are characterized by an architecture constituted by various autonomous nodes which hold information, and are linked to each other by means of mappings. Another technical progress, somehow orthogonal to the aforementioned one, is the one that concerns with the impressive growth of Internet and the consequent proposal of the XML standard for the exchange of data on the Web. Our goal is to develop a formal framework that captures all the issues related to hierarchical data integration systems, whose global schema is expressed by means of an XML schema language. In particular, we will start by considering the case of a global schema specification given by means of a DTD and a set of XML integrity constraints. Moreover, we plan to investigate issues related to XML-based P2P data integration systems. Our research will be done in joint supervision of the department of Computer Science of the University of Rome ”La Sapienza” and the GEMO Project, born from the merging of INRIA-Rocquencourt Verso Project and the IASI group of the University of Paris-Sud.