Fault Tolerant Mobile Agent Systems by using Witness Agents and Probes

In Mobile agents systems, agents can perform their programs with traveling from the server to others and fault tolerance is important in their itinerary. In the paper, existent methods of fault tolerance in mobile agents are considering and described. Then the method is considered that which uses cooperating two agents to fault tolerance, to detect and to recover server and agent failure, meaning three type of agents involved : actual agent which performs programs for its owner, witness agent which monitors the actual agent and the witness agent after itself, probe which is sent for recovery the actual agent or the witness agent on the side of the witness agent. Communication mechanism is message passing between these agents. Traveling agent through servers, the witness is created by actual agent. Scenarios of failure and recovery of server and agent are discussed in the method. During performing the actual agent, the witness agents and probe are increased by addition the servers. Proposed scheme is that minimizes the witness agents as far as possible. Number of created witnesses and number of created probes until any server are considered and evaluated too. This method is Simulated by C-Sim.