GROUP COMMUNICATIONS ALGORITHM FOR DYNAMICALLY UPDATING IN DISTRIBUTED SYSTEMS

This paper proposes a novel updating technique. dynamically updating, for achieving extension or modification of functions in a distributed system. Usual updating technique requires synchronous suspension for m ultiple processes for avoiding unspecified reception caused by the con flict of different versions of processes. Thus, this technique needs v ery high overhead and it must restrict the types of distributed system s, to which it can be applied, to RPC (remote procedure call) type or client-server type. Using the proposed dynamically updating technique, updating management can be invoked asynchronously by each process wit h assurance of correct execution of the system, i.e., the system can c ope with the effect of unspecified reception caused by mixture of diff erent version processes. Therefore, low overhead updating can be achie ved in partner type distributed systems, that is more general type inc luding communications systems or computer networks. Dynamically updati ng technique is implemented by using a novel distributed algorithm tha t consists of group communication, checkpoint setting, and rollback re covery. By using the algorithm proposed in this paper. rollback recove ry can be achieved with the lowest overhead, i.e., a set of checkpoint determines the last global state for consistent rollback recovery and a set of processes that need to rollback simultaneously is the smalle st one. This paper also proves the correctness of the proposed algorit hm.