Dynamic Composition of Cyber-Physical Systems

Future cyber-physical systems must fulfill strong demands on timeliness and reliability, so that the safety of their operational environment is never violated. At the same time, such systems are networked computers with the typical demand for reconfigurability and software modification. The combination of both expectations makes established modeling and analysis techniques difficult to apply, since they cannot scale with the number of possible operational constellations resulting from the dynamics. The problem increases when components with different non-functional demands are combined to one cyber-physical system and updated independent from each other. We propose a new approach for the design and development of composable, dynamic and dependable software architectures, with a focus on the area of networked embedded systems. Our key concept is the specification of software components and their non-functional composition constraints in the formal language TLA+. We discuss how this technique can be embedded in an overall software design workflow, and show the practical applicability with a detailed resource scheduling example.