Observable interface behaviour and inheritance

Abstract

This paper formalizes the observable interface behaviour ofopensystems for a strongly-typed, concurrent object-oriented language with single-class inheritance. We formally characterize the observable behaviour in terms of interactions at the program-environment interface. The behaviour is given by transitions between contextual judgments, where the absent environment is represented abstractly as assumption context. A particular challenge is the fact that, when the system is considered as open, code from the environment can be inherited to the component and vice versa. This requires to incorporate an abstract version of the heap into the environment assumptions when characterizing the interface behaviour. We prove the soundness of the abstract interface description.