Encapsulation and Behavioral Inheritance in a Synchronous Model of Computation for Embedded System Services Adaptation

International audienceBecause it encourages the incremental development of software and the reuse of code by abstracting away implementation details, object orientation is an intuitive and sensible way to conceive large software out of existing application components and libraries. In practice, however, object-orientation is most of the time applied and used with sequentiality in mind. This practice may sometimes be conceptually inadequate for, eg., control-dominated reactive system components. We address this issue by proposing a process calculus that melts the paradigm of synchronous programming to key object-oriented features: encapsulation and behavioral inheritance with overriding by means of specific algebraic concurrency combinators. This framework provides support for the reuse of components and, more specifically, for the adaptation of embedded systems with new services. Cast in the context of a strict interpretation of the synchronous hypothesis, the proposed model supports a static interpretation of inheritance: overriding is resolved at compile-time (or link-time) and inheritance combinators are translated into primitive synchronous ones. This compilation technique puts object-orientation to work in a syntax-oriented model of synchronous concurrency that naturally supports the incremental, refinement-based design of concurrent systems starting from encapsulated and reused application components. The benefits of our approach are illustrated by a concrete and practical example: the adaptation of services to a plain old telephone service specification