Distributed systems have progressed by the large scale integration technology and the advent of local area networks. The distributed systems have made a set of workstations an affordable system with the dame guaranteed computer capacity at all times. In the distributed systems, cooperating processes on different hosts on a network can be shown as a single logical entity, called a group. Groups are introduced to promote performance, fault tolerance and availability of distributed services. To support group communications, new communication protocols are needed.
Group interactions can be thought of as communications between two logical objects: the set of member processes in a group can be shown as a single logical object. Such group communications consist of inter and intra-group communications. By means of such abstraction, group interactions can be separately thought as consisting of inter-group communications and intra-group communications. To make Group Interaction system work correctly and efficiently, there should be effective inter- and intra-group communication mechanisms.
A set of intra-group protocols should guarantee reliability and effectiveness in group interactions. If a set of intra-group protocols are provided for applications, those applications can choose cost-effective one among the intra-group protocols. We proposed an appropriate set of intragroup protocols, designed their engineering model, and implemented a subset of the proposed intra-group protocols. Keywords: group, interaction modes, multicast protocol, RPC, REX, GEX, intra-group protocols.