REPLICATED DISTRIBUTED PROGRAMS.

Abstract

A troupe is a set of replicas of a module, executing on machines that have independent failure modes. Troupes are the building blocks of replicated distributed programs and the key to achieving high availability. Individual members of a troupe do not communicate among themselves, and are unaware of one another's existence; this property is what distinguishes troupes from other software architectures for fault tolerance. Replicated procedure call is introduced to handle the many-to-many pattern of communication between troupes. The semantics of replicated procedure call can be summarized as exactly-once execution at all replicas. An implementation of troupes and replicated procedure call is described, and its performance is measured. The problem of concurrency control for troupes is examined, and a commit protocol for replicated atomic transactions is presented. Binding and reconfiguration mechanisms for replicated distributed programs are described.