Wildcard Search in Structured Peer-to-Peer Networks

We address wildcard search in structured peer-to-peer (P2P) networks, which, to our knowledge, has not yet been explored in the literature. We begin by presenting an approach based on some well-known techniques in information retrieval (IR) and discuss why it is not appropriate in a distributed environment. We then present a simple and novel technique to index objects for wildcard search in a fully decentralized manner, along with some search strategies to retrieve objects. Our index scheme, as opposed to a traditional IR approach, can achieve quite balanced loads, avoid hop spots and single point of failure, reduce storage and maintenance costs, and offer some ranking mechanisms for matching objects. We use the compact disc (CD) records collected in FreeDB (http://freedb.org) as the experimental data set to evaluate our scheme. The results confirm that our index scheme is very effective in balancing the load. Moreover, search efficiency depends on the information given in a query: the more the information, the higher the performance.