PUBLICATIONS A group communication protocol for CORBA," with L. E. Moser, P. M . ABSTRACT The InterGroup Protocols: Scalable Group Communication for the Internet by Karlo BerketReliable group ordered delivery of multicast messages in a distributed system is a useful service that simpli es the programming of distributed applications. Such a service helps to maintain the consistency of replicated information and to coordinate the activities of the various processes. With the increasing popularity of the Internet, there is an increasing interest in scaling the protocols that provide this service to the environment of the Internet. The InterGroup protocol suite, described in this dissertation, provides such a service, and is intended for the environment of the Internet with scalability t o large numbers of nodes and high latency links.The InterGroup protocols approach the scalability problem from various directions. They rede ne the meaning of group membership, allow v oluntary membership changes, add a receiver-oriented selection of delivery guarantees that permits heterogeneity of the receiver set, and provide a scalable reliability service.The InterGroup system comprises several components, executing at various sites within the system. Each component provides part of the services necessary to implement a group communication system for the wide-area. The components can be categorized as: 1 control hierarchy, 2 reliable multicast, 3 message distribution and delivery, and 4 process group membership.We h a v e implemented a prototype of the InterGroup protocols in Java, and have tested the system performance in both local-area and wide-area networks.vii viii 1