An Approach for Composing Multiple Control Loops Hierarchically

To ensure self-adaptation, the Manager Subsystem must include Control Loop (CL). However, create and perform a single CL able to achieve multi-attributes self-adaptation is difficult. So, the system must include many CLs to ensure separation of concerns. The major challenge is that how multiple CL entities can interact with each other to coordinate the system management? On the other hand, how concerns can separate among different CLs? In this paper, we propose HCLs (Hierarchical Control Loops), a pattern for the manager sub-system, with benefits from the leveraging of the hierarchical and dynamic component model, Fractal. The proposed approach allows managing the complexity of self-adaptation by separating concerns using Fractal component model in the form of an hierarchy of MAPE loops. Furthermore, we distinguish three types of adaptations as following: Local Adaptation, Regional Adaptation, and Superior Adaptation in order to achieve multi-level adapting.