Behavioural Contracts for a Sound Assembly of Components

Component based design is a new methodology for the construction of distributed systems and applications. In this new setting, a system is built by the assembly of (pre)-existing components. Remains the problem of the compositional verification of such systems. We investigate methods and concepts for the provision of ”sound” assemblies. We define an abstract, dynamic, multi-threaded, component model, encompassing both client/server and peer to peer communication patterns. We define a behavioural interface type language endowed with a (decidable) set of interface compatibilty rules. Based on the notion of compliance of components to their interfaces, we define the concepts of ”contract” and ”contract satisfaction”. This leads to the notion of sound assemblies of components, i.e., assemblies made of contracted components interacting through compatible interfaces. Sound assemblies possess interesting properties like ”external deadlock freeness” and ”message consumption”.