Indexing Views to Route and Plan Queries in a Peer Data Management System

Abstract

P2P computing gains increasing attention lately, since it provides the means for realizing computing systems that scale to very large numbers of participating peers, while ensuring high autonomy and fault-tolerance. Peer Data Management Systems (PDMS) have been proposed to support sophisticated facilities in exchanging, querying and integrating (semi-)structured data hosted by peers. In this thesis, we are interested in routing and planning graph queries in a PDMS, where peers advertise their local bases using fragments of community RDF/S schemas (i.e., views). We introduce an original encoding for these fragments, in order to e#ciently check whether a peer view is subsumed by a query. We rely on this encoding to design an RDF/S view lookup service featuring a stateless and a statefull execution over a DHT-based P2P infrastructure. We design and implement a mechanism based on an interleaved execution of the routing and planning activities in order to distribute the processing of a query. We finally evaluate experimentally our system (a) to demonstrate its scalability for large P2P networks and arbitrary RDF/S schema fragments, (b) to estimate the number of routing hops required by the two versions of our lookup service and (c) to demonstrate the degree of distribution achieved by the interleaved query routing and planning. To the best of our knowledge this is the first system o#ering the aforementioned functionality and performance