State synchronization and recovery for strongly consistent replicated CORBA objects

The Eternal system provides transparent fault tolerance for CORBA applications, without requiring the modification of either the application or the ORB. Eternal replicates the application objects, and ensures strong replica consistency by employing reliable totally-ordered multicast messages for conveying the IIOP messages of the application. To maintain replica consistency even as replicas fail and are recovered, Eternal ensures the retrieval, assignment and transfer of the three kinds of state, application-level, ORB/POA-level and infrastructure-level state, that are associated with each replicated object. Eternal's mechanisms for recovery include the synchronization of the the state retrieval and the state assignment messages, as well as the logging and replay of messages and checkpoints.