Weak consistency group communication for wide-area systems

Replicated services can be implemented as process groups. Member processes use group communication protocols to communicate amongst themselves and group membership protocols to determine what processes are in the group. These protocols can provide various levels of consistency between members. The author investigates weak consistency protocols that guarantee that messages are delivered to all members, but do not guarantee when. He reports on a new family of communication protocols, an associated group membership mechanism, and current progress in evaluating their efficiency and utility for real applications