A fault-tolerant protocol for providing the exactly-once property of mobile agents

Mobile agent technology has been proposed for various fault-sensitive application areas, including electronic commerce, systems management and active messaging. Due to the autonomy of mobile agents, there is no natural instance that monitors the progress of an agent's execution. As a result, agents may be lost or blocked due to node crashes or network partitioning even if there are other nodes available that could continue processing. In this paper, we describe a protocol that provides exactly-once semantics of agent execution and additionally reduces the blocking probability of agents by introducing observer nodes for monitoring the progress of agents. This protocol is based on conventional transactional technology such as defined by X/Open DTP or CORBA OTS. It is being implemented in Mole, a mobile agent system developed at Stuttgart University.