A Dynamic Shadow Approach for Mobile Agents to Survive Crash Failures

Fault tolerance schemes for mobile agents to survive agent server crash failures are complex since developers normally have no control over remote agent servers. Some solutions modify the agent server platform, e.g. a replica of the mobile agent is injected into stable storage upon its arrival at an agent server. However in the event of an agent server crash the replica remains unavailable until the agent server recovers. This paper presents a failure model and a revised exception handling framework for mobile agent systems. An exception handler design is presented for mobile agents to survive agent server crash failures. A replica mobile agent operates at the agent server visited prior to its master’s current location. If a master crashes its replica is available as a replacement. Experimental evaluation is performed and performance results are used to suggest some useful design guidelines.