A lot of recent work has dealt with improving performance of content searching in peer-to-peer file sharing systems. In this paper we attack this problem by modifying the overlay topology describing the peer relations in the system. More precisely, we create a semantic overlay, linking nodes that are “semantically close”, by which we mean that they are interested in similar documents. This semantic overlay provides the primary search mechanism, while the initial peer-to-peer system provides the fail-over search mechanism. We focus on implicit approaches for discovering semantic proximity. We evaluate and compare three candidate methods, and review open questions. 1.

In the offline world, we look to the people we trust and those they trust for reliable information. In this paper, we present a computational model of this phenomenon and show how it can be used to identify high quality content in an Open Rating System, i.e., a system in which any user can rate content. We present a case study (Epinions.com) of a system based on this model and describe a new platform called PeopleNet for harnessing this phenomenon in an open distributed fashion. 1.

We are going to address several important challenges and issues on Semantic Web Service Constraint Satisfaction Problem (SWSCSP) for P2P systems. The marriage of semantic web and web services has been considered as one of the most important research areas to lift o# semantic web vision on the WWW. The (semantic) web services will be a runaway train if we do not have any constraint and control mechanisms for the entire service process. Unfortunately people did not pay attention on this issue until recently so the results are very scare and primitive [20]. The service constraints are defined as policies that can be specified by combination of ontology and rules. Therefore the OWL Rule Language (ORL) will be the best candidate to declare semantic web service constraints. Furthermore, our SWSCSP research will focus on P2P systems and this infrastructure is more complex and dynamic than the WWW on policy management and enforcement.