With the increasingly huge amount of data located in various databases and the need for users to access them, distributed information retrieval (DIR) has been at the core of the preoccupations of a number of researchers. Indeed, numerous DIR systems and architectures have been proposed including the broker-based architecture. Moreover, providing DIR with more flexibility and adaptability has led researchers thinking to build DIR with software agents. Thus, this research proposes a design and an implementation of a novel system based on the broker-based architecture and the peer-to-peer (P2P) network called broker-based P2P network. The proposed architecture is implemented with a multi-agent system (MAS) where the main agent playing the role of the broker, receives query from a peer agent and forwards them to other peer agents each with their index and resources. Upon completing retrieval process at each peer agent, results are directly sent to the peer agent that initiated the query without using the broker agent. Java Agent DEvelopment framework (JADE) is used to implement the agents and, for experiments, TERRIER (TERabyte RetRIEveR) is extended and used as the search engine to retrieve the Text Retrieval Conference (TREC) collections dataset notably TREC-6. The peer agent that originated the query progressively collects results coming from other peer agents, normalises and merges them and then proceeds with re-ranking. For normalisation, MinMax and Sum that are unsupervised normalisation methods are used.
A Suite of Testbeds for the Realistic Evaluation of Peer-to-Peer Information Retrieval Systems
