Peer-to-peer content search supported by a distributed index in a publication/search model

Peer to-peer networks (P2P) are considered a valid approach for the construction of distributed systems. Further research projects in the last few years have focused on using this kind of networks as an alternative for solving different situations that have traditionally required centralized servers, such as search engines. This paper deals with the problem of content search in highly distributed and dynamic environments. We propose and evaluate a distributed index model built upon a peer-to-peer network which supports complete indexing of text documents and allows searching by content. A distinctive feature of this proposal is that it requires no specific network topology or hierarchy. Evaluations with different settings were performed by simulating a 10,000-node network, where each node had the capability to share documents. With regard to the traffic generated, experiments show an improvement in efficiency of between 84% and 93% over similar systems like Gnutella. The evaluation of retrieval performance using a test collection showed that the P2P system was able to achieve the same level of performance as the centralized system. It was also found that the amount of traffic generated by this model varies between 80 and 225 Kb per set of query and answers.