Modeling Fault-Tolerant and Reliable Mobile Agent Execution in Distributed Systems

The reliable execution of a mobile agent is a very important design issue in building a mobile agent system and many fault-tolerant schemes have been proposed so far. To further develop mobile agent technology, reliability mechanisms such as fault tolerance and transaction support are required. For this purpose, we first identify two basic requirements for fault-tolerant mobile agent execution: (1) non-blocking (i.e., a single failure does not prevent progress of the mobile agent execution) and (2) exactly-once (i.e., multiple executions of the agent are prevented). To achieve fault tolerance for the agent system, especially for the agent transfer to a new host, we use Distributed Transaction Processing. This paper proposes a novel approach to fault-tolerant mobile agent execution, which is based on modeling agent execution as a sequence of agreement problems. Each agreement problem is one instance of the well-understood consensus problem. Our solution does not require a perfect failure detection mechanism, while preventing blocking and ensuring that the agent is executed exactly once. We derive the Fault-Tolerant approach for Mobile Agents design which offers a user transparent fault tolerance that can be activated on request, according to the needs of the task, also discuss how transactional agent with types of commitment constraints can commit. Furthermore we propose a solution for effective agent deployment using dynamic agent domains. Key-Words: Fault-Tolerant, Mobile Agent, Security, Network Management , Crash ,Failures, , Replication.