Verifying Stochastic Behaviors of Decentralized Self-Adaptive Systems: A Formal Modeling and Simulation Based Approach

The development of self-adaptive software has attracted a lot of attention. Decentralization is an effective way to manage the complexity of modern self-adaptive software systems. However, there are still tremendous challenges remained in decentralized self-adaptive systems. One major challenge is to guarantee the achievements of both local goals and global goals. Another challenge is to ensure the performance of the systems operating in highly dynamic environments with existence of internal changes. To solve these problems, we introduce an integrated system framework combining self-adaptive mechanisms with decentralization features, with a formal modeling method based on stochastic timed automata to allow the system to be analyzed and verified. Timed computational tree logic is used to specify the system properties and then stochastic simulations in a dynamic environment are conducted to study system performance. The whole approach is illustrated and evaluated with a motivation example from practical applications in UAV emergency mission scenarios.