Efficient Query Routing in RDF/S schema based P2P Systems

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. However, existing P2P systems offer poor data management facilities, limited to IR-style keyword search using eventually a fixed set of document attributes. Schema-based P2P systems have been proposed to support richer facilities in exchanging, querying and integrating structured and semi-structured data hosted by peers. In this paper, we address routing issues for expressive queries in schema-based P2P systems, where peers advertise their local bases using fragments of a community RDF/S schema (i.e., views). We then introduce an original encoding of RDF/S schema fragments, allowing to efficiently 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 centralized and distributed execution over a DHT-based P2P system. We finally evaluate experimentally the proposed framework to demonstrate its scalability for large P2P networks and arbitrary RDF/S schema fragments, as well as, to estimate the number of routing hops required by the two versions of our lookup service.