Communication Protocol for Wide-area Group

Distributed systems are composed of multiple computers interconnected by communication networks. Group communication protocol supports the ordered and reliable delivery of messages to multiple destinations in a group of processes. The group communication protocols discussed so far assume that the delay time between every two processes is almost the same. In world-wide applications using the Internet, it is essential to consider a wide-area group communication where the delay times among the processes are signi cantly di erent. We de ne newly a -causality to be applied in the wide-area group. We present a protocol which supports a group of processes with the -causality.