Exploiting semantics in structured P2P systems

A fundamental challenge in Peer-To-Peer (P2P) systems is how to locate objects of interest, namely, the look-up service problem. In the distributed hash table (DHT), including Chord, CAN, Pastry and Tapestry, among others, both object id and network node are randomly hashed to a same id space, so that ¿locality-awareness¿ is not inbuilt in the basic DHT design. Therefore, objects are referred to in a location-independent manner. In this paper, we propose an semantic approach to build a P2P system called SemanticChord which aims to integrate and organize the data/information resources based on the domain of interest to route requests to the most likely physical location of data. We apply the Topic maps approach as a semantic layer in aggregating and organizing resources based on the domain of interest on top of the Chord Protocol. Experimental results show that SemanticChord improves the traditional DHT-based Chord in terms of average number of messages per lookup (11%), the average success rate for content location (6%) and response time.