Using dynamic proxy agent replicate groups to improve fault-tolerance in multi-agent systems

Despite the considerable effort spent researching and developing multi-agent systems the actual number of deployed systems is still surprisingly small. One of the reasons for the significant gap between developed and deployed systems is their brittleness. Multi-agent systems are susceptible to all of the same faults as any distributed system, they lack centralized control components, which makes it difficult to detect and treat failures of individual agents, and the agents making up the system are social, thus risking fault-propagation These faults can impact system performance and lead to overall system failure. Multi-agent systems must be made more dependable before they will be deployed on a large scale. Using redundancy by replication of individual agents within a multi-agent system is one possible approach for improving fault-tolerance, and hence improving reliability and availability-two key components of dependability. Having a group of agents, a replicate group, act like an individual agent leads to increased complexity and system load, and it introduces new challenges to system construction. Using a message proxy, to handle communication for the group, and passive replication strategies effectively deals with the complexity and overhead issues. This paper presents an architecture for implementing agent replicate groups using a message proxy and passive replicate group management. Experimentation and application testing using an implementation of the architecture is presented. The architecture is demonstrated to be a viable technique for increasing dependability in multi-agent systems.