Relatrice: dott.ssa Angela Bonifati

lunedì 18 luglio 2005, ore 15:30, aula 39 del Dipartimento di Matematica (III Piano Facoltà di Scienze)

Sommario: We study a collection of heterogeneous XML databases containing similar and related information, exchanging data via a peer to peer overlay network. Here, a mediated global schema is unrealistic. Yet, users/applications wish to query the databases, via one peer using its schema. We have recently developed HepToX, a P2P Heterogeneous XML database system. A key idea is that whenever a peer enters the system, it establishes an acquaintance with a small number of peer databases. The peer administrator provides correspondences between the local schema and the acquaintance schema using an intuitive notation of arrows and boxes, from which our novel algorithm infers a precise set of mapping rules. We pin down the semantics of query answering, and present a query translation algorithm for a simple but expressive fragment of XQuery. We show the translation algorithm is correct. Finally, we demonstrate the utility and scalability of our ideas and algorithms with a detailed set of experiments on top of the Emulab, a large scale P2P network emulation testbed. This is joint work with Elaine Q. Chang, Laks V.S. Lakshmanan and Terence Ho, University of British Columbia (Canada)