Models and analysis for user-driven reconfiguration of rule-based IoT applications

Introduction: The Internet of Things consists of devices and software interacting altogether in order to build powerful and added-value services. One of the main challenges in this context is to support end users with simple, user-friendly, and automated techniques to design such applications. IFTTT-style rules are a popular way to build IoT applications as it addresses this challenge. Problem statement: Given the dynamicity of IoT applications, these techniques should also consider that these applications are in most cases not built once and for all. They can evolve over time and objects may be added or removed for several reasons (replacement, loss of connectivity, upgrade, failure, etc.). There is a need for techniques and tools supporting the reconfiguration of rule-based IoT applications to ensure certain correctness properties during this update tasks. Methodology: In this paper, we propose new techniques for supporting the reconfiguration of running IoT applications, represented as a set of coordinated rules acting on devices. These techniques compare two versions of an application (before and after reconfiguration) to check if several functional and quantitative properties are satisfied. This information can be used by the user to decide whether the actual deployment of the new application should be triggered or not. Contributions and results: The analysis techniques have been implemented using encodings into formal specification languages and verification is carried out using corresponding analysis frameworks. All these techniques for designing new applications, analysing the aforementioned reconfiguration properties, and deploying the new applications have been integrated into the WebThings platform and applied on real-world examples for validation of the approach.