Hierarchical Formal Modeling of Internet of Things System Oriented to User Behavior

Ensuring the correctness and reliability of the Internet of Things system is the key to the advancement of the Internet of Things project. It is very necessary to fully inspect the Internet of Things system before it is actually deployed, so as to find the errors and defects in the system design as soon as possible and make improvements. Compared with conventional simulation and testing, the formal method has the advantages of low cost, short cycle and simple steps, which provides efficient support for the inspection and analysis of the Internet of Things system before deployment. Based on the stateful timed communication sequence process (STCSP), we consider the formal modeling framework for the Internet of things system from the perspective of external environment input and system architecture. We then propose a hierarchical formal modeling method for the Internet of things system oriented to user behavior. Taking the elderly home monitoring application scene as an example, as the input of the external environment, the user behavior and its implementation object are combined into a whole for modeling, so as to keep the two states in sync, restrict each other, and avoid unrealistic sequence of activities. From the perspectives of perception mode, communication mode, predefined rules and application services, we have completed the hierarchical modeling of the three-layer architecture of the Internet of Things system, that is, perception layer, middle layer and application layer. Finally, the model verification tool PAT analyzes and verifies the above model from the aspects of security, accessibility, and system consistency. This method provides scientific basis for the correctness inspection and reliability analysis of the Internet of Things system before deployment in the Internet of Things project.