Newcastle upon Tyne, NE1 7RU, UK. Exception Handling in Coordination-based Mobile Environments

Abstract. Interest in mobile agent systems is sharply increasing. Mobile agent systems have many attractive features, including asynchrony, openness, dynamicity and anonymity, making them indispensable in designing complex modern applications which involve moving devices, human participants and software. To make these systems useful this list should include fault tolerance, but unfortunately as our analysis shows this characteristics is often overlooked by the middleware designers. The few existing solutions for fault tolerant mobile agents are developed for tolerating exclusively hardware faults without providing any general support for the application-specific recovery. In this paper we describe a novel exception handling model that allows applicationspecific recovery in the coordination-based systems consisting of mobile agents. The proposed mechanism is general enough to be used in both loosely-and tightly-coupled communication models. The general ideas behind the mechanism are applied in the context of the Lime middleware and demonstrated with two examples.