Formal Models for Analysing Dynamic Adaptation Behaviour in Real-Time Systems

Abstract

Self-adaptive systems are able to autonomously adapt themselves to react to dynamic changes in their environment. They, thereby, provide suitable mechanisms to deal with uncertain environment settings, as is required in modern reactive systems, such as cyber-physical systems. However, design and analysis of adaptation logic is complex and error-prone. Thus, early design-time analysis of the adaptation logic is necessary, especially in safety-critical applications. In this paper, we cope with the problem of comprehensively analysing time-dependent self-adaptive systems. We consider rule-based adaptation as a generic mechanism to describe adaptation logic. We automatically extract formal timed models of the functional components from a SystemC system-level implementation. This ensures that analysis results on the models correspond to the actual running system. To analyse the adaptation behaviours, we embed the extracted functional models in a formal, generic, and abstract MAPE-K loop modelled with timed automata. We classify important adaptation properties and show how they can be generally verified on the resulting models together with an abstract model of the environment, which we assume to be given. To evaluate our approach, we analyse the widely used web-based information system Znn.com.