A unified approach for modeling, developing, and assuring critical systems

Abstract

Developing and assuring safety- and security-critical real-time embedded systems is a challenging endeavor that requires many activities applied at multiple levels of abstraction. For these activities to be effective and trustworthy, they must be grounded in a common understanding of the system architecture and behavior. We believe that these activities are best addressed in a unified framework of modeling and programming that enables developers, analysts, and auditors to freely move up and down layers of abstraction, shifting their viewpoints to suit the activities at hand, while maintaining strong traceability across the different layers and views. In this approach, the distinction between “models”, “specifications”, and “programs” is often blurred. In this paper, we summarize an architecture-centric approach to critical system development and assurance that emphasizes the use of formally specified architectures as the “scaffolding” through which many different activities are organized and synchronized. We provide examples of: (a) analyses, behavioral constraints, and implementations, (b) important abstraction transitions, and (c) key traceability relationships within the framework. We discuss how these features are being used to develop systems on time and space partitioned execution and communication platforms for systems in the medical domain. We use an open-source medical device that we are developing – Patient-Controlled Analgesic (PCA) infusion pump as a concrete example.