A Model of Behaviour Abstraction for Communicating Processes

We investigate the notion that a system, or process, is an acceptable implementation of another base or target process, in the case that they have different interfaces. Base processes can be thought of as specifications, or ideal processes operating in an error-free environment, while implementations model their actual realisation, possibly employing a variety of fault-tolerant techniques. Using the CSP model, we relate implementations to targets in terms of their observable behaviours, through interface abstraction. We obtain two basic results: realisability and compositionality. The former ensures an implementation up to interface abstraction can be put to good use, in the sense that plugging it into an appropriate environment yields a conventional implementation. Compositionality requires that a target made up of subcomponents can be implemented by assembling their respective implementations.