Foreseer: A Novel, Locality-Aware Peer-to-Peer System Architecture for Keyword Searches

Peer-to-peer (P2P) systems are becoming increasingly popular and complex, serving millions of users today. However, the design of current unstructured P2P systems does not take full advantage of rich locality properties present in P2P system workloads, thus possibly resulting in inefficient searches or poor system scalability. In this paper, we propose a novel locality-aware P2P system architecture called Foreseer, which explicitly exploits two dimensional localities, both geographical locality and temporal locality by constructing a neighbors overlay and a friends overlay respectively. Each peer in Foreseer maintains a small number of neighbors and friends as well as their content filters used as distributed indices. By combining the advantages of distributed indices and utilization of two dimensional localities, the search scheme of Foreseer is able to satisfy more than 99% keyword search queries, realize very high search performance and introduce low maintenance cost. In addition, query messages rarely touch free-riders, namely avoiding a lot of meaningless messages for P2P systems. Our simulation results show that, compared with current unstructured P2P systems, Foreseer can boost the searching efficiency with an introduction of modest maintenance cost.