Remote Reliable Services to Support Transactional Mobile Agents

Mobile devices are now equipped with multiple sensors and networking capabilities. They can gather information about their surrounding environment and interact both with nearby nodes, using a dynamic and self-configurable ad-hoc network, and with distant nodes via the Internet. While the concept of mobile agent is appropriate to explore the ad-hoc network and autonomously discover service providers, it is not suitable for the implementation of strong distributed synchronization mechanisms. Moreover, the termination of a task assigned to an agent may be compromised if the persistence of the agent itself is not ensured. In the case of a transactional mobile agent, we identify two services, Availability of the Source and Atomic Commit, that have to be supplied by more powerful entities located outside the ad-hoc network, in a remote network, called the support network. We propose a solution where the two services are successively provided by an active entity called the leader. In the support network, crash failures may also occur. To guarantee reliability, the main actions performed by the leader are the subject of a consensus with all the other potential leaders. The proposed solution relies on a single agreement protocol that orders continuously all the new actions.