Formal Development of Cooperative Exception Handling for Mobile Agent Systems

摘要

Mobile agent systems often require sophisticated cooperation and coordination during error detection and recovery. In this paper we propose novel fault tolerance mechanisms that support cooperative exception handling in such systems.The paper demonstrates how mechanisms like these can be formally developed and analysed. We start with identifying modes of failures in agents and analysing possible failure and recovery scenarios in mobile systems. Stepwise refinement is used as our formal framework for top-down development and verification. Using the framework we formally verify the essential model properties, such as interoperability, local and global state consistency and termination of error recovery. Our approach provides developers with formal generic patterns for incorporating fault-tolerance mechanisms into mobile agent systems. We also demonstrate how the results of our formal development can be instantiated and reused in developing real-world agent software.