A Model-Based Framework for Building Self-Adaptive Distributed Software

Abstract

Reconfiguration is widely used for evolving and adapting systems that cannot be shut down for update. However, in distributed systems, supporting reconfiguration is a challenging task since a reconfiguration consists of distributed reconfiguration actions that need to be coordinated and the application consistency must be preserved. To address this challenge, we propose a framework based on a reflexive three layer architecture model for the development of distributed dynamic and reliable component-based applications. The bottom layer of this model is the application layer. It contains the system's application-level functionality. The change management layer is the middle layer. It reacts to changes in state reported from the application layer. The uppermost layer is the self-adaptation layer that introduces the self-adaptation capabilities to the framework itself. It ensures the service continuity of the change management layer and manages the adaptation of this last to the changes which it carries out itself on the application layer. The framework is conceived especially for supporting the distributed reconfigurations. For that, it incorporates a negotiation and coordination mechanism for managing this type of reconfiguration. Moreover, it incorporates a separate system for ensuring the reliability of the application. The paper introduces a prototype implementation of the proposed framework and its empirical evaluation.