Ontology-Addressable Contents in P2P Networks

A critical issue for P2P systems is to perform an effective content retrieval taking into account semantic properties of what is searched. Important requirements to be considered for knowledge sharing in P2P systems are related to the inherent dynamism of the P2P context demanding for a decentralized sharing and administration of knowledge and to the role of Semantic Web techniques to support data semantics representation and rich query languages for content retrieval. In this paper, we describe a comprehensive framework, called H, for ontologyaddressable contents in P2P systems, which is composed by a knowledge infrastructure layer (Helios) and a communication infrastructure layer (Hermes). The H framework proposes to build an overlay network among peers in which each peer maintains a peer ontology describing its knowledge of the network. For query routing, the topology of the overlay network mirrors the semantic neighborhood of the peers given by the semantic relationships among the ontologies they own.