Using Coordinated Atomic Actions to Design Safety-Critical Systems: a Production Cell Case Study

Coordinated Atomic actions (CA actions) are a unified approach to structuring complex concurrent activities and supporting error recovery between multiple interacting objects in object-oriented systems. This paper explains how we have used the CA action concept to design and implement a safety-critical application. We have used the Production Cell model that was developed in the Forschungszentrum Informatik (FZI), Karlsruhe, Germany, to present a realistic industry-oriented problem, where safety requirements play a significant role. Our design consists of two levels: the first level deals with the scheduling of CA actions, and the second level deals with the interactions between devices. Both the scheduling mechanism and the device interactions are enclosed by CA actions. Exception handling and error recovery are incorporated into CA actions in order to satisfy high safety and fault tolerance requirements. A controlling program based on our design was developed in the Java language and used to drive a graphical simulator provided by the FZI.