Object Group A ( Active Replication ) Method N Eternal ORB Method N ERM

The Eternal system enhances the CORBA standard to provide fault tolerance within distributed systems that are susceptible to network partitioning. Fault tolerance is achieved through consistent replication of both client and server objects. Objects may be actively or passively replicated, and replicated objects of both types may coexist. Nested operations involving both active and passive objects are accommodated. Suppression of duplicate operations is ensured by unique message and operation identifiers. Continued operation is allowed in all components of a partitioned network. State transfer mechanisms and fulfilment operations restore the consistency of the states of the replicas when communication is re-established and the components remerge.