A specification and verification of intermittent global order broadcast

Abstract

The goal of my thesis is to specify, model and verify intermittent global order broadcast. Broadcast means that every process in the system receives a copy of every message. Global order means that all processes deliver the messages in the same order. Intermittent global order means that global order holds (luring periods of stability and there are no guarantees during periods of instability. A group of processes is stable if each process can communicate with each other process with some minimal quality of service and no process can communicate with another process outside the group. Intermittent properties, such as intermittent global order, are useful for certain collaborative applications operating in dynamic environments. They help balance conflicting needs for the different applications. We want to be able to formally specify intermittent properties in order to precisely express the guarantees provided by these applications and to be able to verify the algorithms implementing these properties. Because the guarantees hold intermittently, simply stating a definition and building a state-machine specification for an intermittent property is non-trivial. The same is true about verifying that an algorithm satisfies an intermittent property. Existing specification and verification techniques may need to be adjusted.