Abstract

Agreement protocols have been extensively used by distributed data management systems to provide robustness and high availability. The broad spectrum of design dimensions, applications, and fault models have resulted in different flavors of agreement protocols. This proliferation of agreement protocols has made it hard to argue their correctness and has unintentionally created a disparity in understanding their design. To address this disparity, we study the chemistry behind agreement and present a unified framework that simplifies expressing different agreement protocols. Specifically, we extract essential elements of the agreement and define atoms that connect these elements. We illustrate how these elements can help to explain and design various agreement protocols.