Interaction interfaces-towards a scientific foundation of a methodological usage of message sequence charts

Abstract

We introduce the formal notion of an interaction interface. Its purpose is to specify formally the interaction between two or more components that co-operate as subsystems of a distributed system. We suggest the use of interaction interfaces for the description not of the behaviour of a single component in isolation but of the interface, the co-operation, between two or more components that are interacting within a distributed system. Typical examples are the interaction between an embedded system and its environment or the interaction between a sender and a receiver in a communication protocol. An interaction interface can be formally described by predicates characterising sets of interaction histories. We understand the specification of interaction histories as a typical step in system development that prepares the decomposition of a system into interacting subcomponents. After fixing the distribution structure of the system, an interaction interface is worked out that describes how the introduced subcomponents interact. In a successive development step we systematically derive the individual component specifications from the interface description. We show how such an interaction interface can be decomposed systematically into component specifications.