Group communications algorithm for dynamically updating in distributed systems

The paper proposes a novel updating technique, dynamically updating to achieve extension or modification of functions in a distributed system. Usual updating techniques require multiple processes to suspend simultaneously in order to avoid an unspecified reception caused by the conflict of different versions of processes. By using the proposed dynamically updating technique, the updating operation can be invoked asynchronously by each process with the assurance of correct execution of the system, i.e., the system can cope with the effect of an unspecified reception caused by a mixture of multiple version processes. This is implemented by using a novel distributed algorithm that consists of group communication, checkpoint setting, and rollback recovery. This algorithm achieves rollback recovery with the lowest overhead, i.e., a set of checkpoints determines the last global state for consistent rollback recovery and a set of processes that need to rollback simultaneously is the smallest