Semantic Query Routing and Processing in P2P Database Systems:

Abstract. Peer-to-peer (P2P) computing is currently attracting enormous attention. In P2P systems a very large number of autonomous computing nodes (the peers) pool together their resources and rely on each other for data and services. More and more P2P data management systems rely nowadays on intensional (i.e. schema) information for integrating and querying peer bases. Such information can be easily captured by emerging Semantic Web languages such as RDF/S. However, a fully-fledged framework for evaluating semantic queries over peer RDF/S bases (materialized or virtual) is missing. In this paper we present the ICS-FORTH SQPeer middleware for routing and processing RQL queries and RVL views. The novelty of SQPeer lies on the use of intensional active schemas for determining relevant peer bases, as well as, constructing distributed query plans. In this context, we consider optimization opportunities for SQPeer query plans.