DeDiSys Lite: an environment for evaluating replication protocols in partitionable distributed object systems

Distributed object systems for partitionable systems present a challenge, in that there is a trade-off between availability and consistency. Changes in one partition are not visible in another partition. Therefore, if strong consistency is required, certain operations cannot be permitted. This reduces availability. In the DeDiSys project we aim at allowing this trade-off between consistency and availability to be configurable. The DeDiSys distributed object system relies heavily on replication protocols that allow high-availability, whilst ensuring a level of consistency that is required by a particular application. We have developed DeDiSys Lite, a prototype of the DeDiSys system, which provides a platform to implement and evaluate these replication protocols. Infrastructure components are provided in a minimal implementation. Configuration files allow system parameters, such as the degree of replication or the nesting of object invocations, to be modified, without having to adapt application code. We use DeDiSys Lite as both a simulation environment for the development of new replication protocols and as a basis for the continuous development of the DeDiSys system. Some results obtained using the platform to optimise a new replication protocol are presented in this paper.