Group Communication Systems
Wenbing Zhao · 2021
This chapter focuses on several group communication systems that are elegantly designed and are representatives of the respective approaches. A group communication system must define two protocols, one for normal operation when all nodes in the current membership can communicate with each other in a timely fashion, and the other for membership change when one or more nodes are suspected as failed, or when the failed nodes are restarted. The chapter describes a more robust sequencer based group communication system. It also describes the rotating sequencer based approach and the design of the Totem (single-ring) group communication system. Using a vector clock at each node in the system can track the causal relationship between different messages accurately. The chapter discusses how to adapt the vector clock based causal ordering protocol when the membership changes.