BestPeer: A Self-Con gurable Peer-to-Peer System

In a peer-to-peer (P2P) distributed system, nodes of equivalent capabilities and responsibilities pool their resources together to share information and services. However, most of the existing P2P systems such as Napster and Gnutella provide a coarse granularity of information sharing (i.e., le level) that ignore the content of the le. Moreover, a node's peers are typically statically de ned. In addition, there is no support for nodes that are connected intermittently with temporary network addresses. In this paper, we present BestPeer, a prototype P2P system that we have implemented at the National University of Singapore. BestPeer is unique in several ways. First, it combines the power of mobile agents into P2P systems to perform operations at peers' sites. This facilitates content-based searching easily. Second, it is selfcon gurable, i.e., a node can dynamically optimize the set of peers that it can communicate directly with based on some optimization criterion. By keeping peers that provide most information or services in close proximity (i.e, direct communication), the network bandwidth can be better utilized and system performance can be optimized. Third, BestPeer provides a location independent global names lookup server to identify peers with dynamic (or unpredictable) IP addresses. In this way, several peers can always collaborate (or share resources) even if their IP addresses may be di erent at di erent occasions. We evaluated BestPeer on a cluster of 32 Pentium II PCs each running a Java-based storage manager. Our experimental results show that BestPeer provides excellent performance compared to traditional non-con gurable models. Further experimental study reveals its superiority over Gnutella's protocol. Keyword: Peer-to-peer, mobile agent, neighbors, dynamic recon guration, replacement policy.