Correctness and Consistency of Event-Based Systems

Event-based systems encounter challenges of correctness and consistency. Correctness means that the execution results match the intention of the designer. Consistency means that different data elements that co-exist within a certain system creates an internal consistency with respect to the system's requirements. In this tutorial, we cover the different aspects of correctness and consistency. We discuss issues of correctness with respect of the temporal properties of the system, such as order of events, and boundaries of time windows. We further discuss the different aspects of fine-tuning required in event-based system, where different semantic interpretations are possible, such as: repeating events, or consumption. The consistency discussion relates to two classic issues in the data management world: data dependencies and integrity constraint enforcement. Since event-based systems typically consist of loosely coupled component architecture in distributed environment, the challenge is compliance with data dependencies and assertions about consistency. Finally, yet importantly, we discuss the validation of event-based systems by using static and dynamic analysis.