Design and implementation of a semantic peer-to-peer network

Decentralized and unstructured peer-to-peer (P2P) networks such as Gnutella are attractive for large-scale information retrieval and search systems due to scalability, fault-tolerance, and self-organizing nature. This decentralized architecture, however, makes it difficult for traditional P2P networks to globally share useful semantic knowledge among nodes. As a result, traditional P2P networks cannot support semantic search (support only naive text-match search). In this paper, we describe one possible design of a semantic P2P network which enables semantic keyword search. We exploit the semantics of correlation among keywords rather than synonym. The key mechanism is query expansion, where a received query is expanded based on keyword relationships. Keyword relationships are improved through search and retrieval processes and each relationship is shared among nodes holding similar data items. Our main challenges are 1) managing keyword relationships in a fully decentralized manner and 2) maintaining the quality of search results, while suppressing result implosion. We also describe the prototype implementation and simple evaluation of the semantic P2P network.