Group communication specifications: a comprehensive study

View-oriented group communication is an important and widely used building block for many distributed applications. Much current research has been dedicated to specifying the semantics and services of view-oriented Group Communication Systems (GCSs). However, the guarantees of different GCSs are formulated using varying terminologies and modeling techniques, and the specifications vary in their rigor. This makes it difficult to analyze and compare the different systems. This paper provides a comprehensive set of clear and rigorous specifications, which may be combined to represent the guarantees of most existing GCSs. In the light of these specifications, over thirty published GCS specifications are surveyed. Thus, the specifications serve as a unifying framework for the classification, analysis and comparison of group communication systems. The survey also discusses over a dozen different applications of group communication systems, shedding light on the usefulness of the presented specifications. This paper is aimed at both system builders and theoretical researchers. The specification framework presented in this paper will help builders of group communication systems understand and specify their service semantics; the extensive survey will allow them to compare their servic