Responsiveness of interoperating components

Abstract.

This paper investigates the issue of responsiveness of interoperating components: one not causing the other to deadlock. This is obviously related to the question of whether the two deadlock when put in parallel. However, it is different in that we require that a specific process P is not itself blocked by a plugin Q when it could otherwise have progressed, instead of asking that either process can always proceed (deadlock freedom). The issue becomes yet more subtle when dealing with processes which can nondeterministically block, either through graceful termination or unfortunate deadlock. The relational predicate, that is, binary relation on processes, which we provide is refinement-closed. This is significant as it allows components to be developed independently. In addition, it can be mechanically verified. The contribution of this paper is to identify the issue of responsiveness; to define appropriate properties; to demonstrate the suitability of these properties and consider how they can be mechanically verified. The notation used is CSP with automatic model-checking provided by the FDR tool.