Tool-Supported Refinement of High-Level Requirements and Constraints Into Low-Level Policies

In the context of the automated technical management of distributed ambient-assisted-living healthcare systems, we employ high-level policies which describe the abstract requirements of the system from the use cases point of view. At runtime, an efficient low-footprint management system is used which executes low-level management rules of the event-condition-action type. The rules represent the low-level management policies. They monitor the status variables of the software components and change the settings of their configuration variables in order to enforce the high-level requirements. We report on the automated, tool-supported refinement of these policies which is based on a three-layered system model. The top layer reflects the use cases, the middle layer the service infrastructure, and the bottom layer the actual software and hardware components. The automated refinement exploits the model and its refinement relations which associate system elements with all those elements representing them on the next lower model layer. Moreover, the automated refinement is controlled by refinement, evaluation, and control pattern instances introduced by the model designer in order to supply the policy refinement and the policy enforcement with "ideas\´\´ to be applied. The paper outlines our management approach and the graphical modeling tool MoBaSeC. The focus is set on the policy refinement functions and on the utilization of refinement, evaluation, and control patterns.