Compositional Development in the Event of Interface Difference

We present here an implementation relation which allows compositional development of a network of communicating processes, in the event that corresponding specification and implementation components have different interfaces. This relation is compositional, in the sense that a target composed of several connected systems may be implemented by connecting their respective implementations. In addition, an implementation, when plugged into an appropriate environment, is to all intents and purposes a conventional implementation of the target. We illustrate our approach by outlining the development of a fault-tolerant system based on coordinated atomic actions (CA actions).