Enabling semantic search in P2P systems through a three-layer Distributed Service Registry

Effective searching and access to data and functionalities in P2P environments require platform independency for integrating different sources over the Web and must take into account the presence of high dynamicity and the absence of a common resource conceptualization. Service Oriented Architecture enables to export shared data and functionalities through Web Services, thus enabling platform-independent resource discovery. In P2P networks, available services are published and retrieved on different registries, that are autonomous and heterogeneous. Semantic Web Service technology is suggested to face semantic heterogeneity. We propose a virtual Distributed Service Registry (DSR) and a reference architecture to support semantic search over P2P networks. The DSR is organized on three layers: a logical layer, in which single registries are connected as peers in a P2P network; a semantic layer, where peer registries are semantic-enriched and semantic links between peer registries holding similar services are established; a mapping layer, where mappings between similar services are defined to support service interoperability between heterogeneous peers. In the reference architecture, each peer is equipped with: a service knowledge evolution manager, to update peer local knowledge through interactions with other peers; a semantic search assistant, that exploits the three-layer organization of the DSR to satisfy requested user searches, also suggesting possible alternative services or related services suitable for composition, on the basis of semantic links.