Consensus Service to Solve Agreement Problems

This paper describes an extension of the Consensus Service proposed by Guerraoui and Schiper. The objective is to provide a standard way to implement agreement protocols resilient to Byzantine faults using an intrusion tolerant service built upon virtual machines technology. This is achieved through the implementation of a Generic Consensus Service (GCS). GCS separates specificities of different agreement problems from consensus in a clear way, using client server interaction, allowing total independence between consensus protocols used and problem specific specializations. Besides that, the framework provides a set of properties and guarantees. It will be shown how the GCS works, its general properties and how it may be used to solve some agreement problems, for instance, reliable and atomic broadcast.