Trustworthy Service Caching: Cooperative Search in P2P Information Systems

We are developing an approach for P2P information systems, where the peers are modeled as autonomous agents. Agents provide services or give referrals to one another to help find trustworthy services. We consider the important case of information services that can be cached. Agents request information services through highlevel queries, not by describing specific objects as in caching in traditional distributed systems. Moreover, the agents autonomously decide whom to contact for a service, whom to provide a service or referral, whether to follow a referral, and whether to cache a service. Thus the information system itself evolves as agents learn about each other and the contents of the caches of the agents change. We study the effect of caching on service location and on the information system itself. Our main results are that (1) even with a small cache, agents can locate services more easily; (2) since the agents that cache services can act like service providers, few initial service providers are enough to serve the information needs of the consumers; and (3) agents benefit from being neighbors with others who have similar interests.