Design of self-managing dependable systems with UML and fault tolerance patterns

Abstract

The development of dependable software systems is a costly undertaking. Fault tolerance techniques as well as self-repair capabilities usually result in additional system complexity which can even spoil the intended improvement with respect to dependability. We therefore present a pattern-based approach for the design of service-based systems which enables self-managing capabilities by reusing proven fault tolerance techniques in form of Fault Tolerance Patterns. The pattern specification consists of a service-based architectural design and deployment restrictions in form of UML deployment diagrams for the different architectural services. The architectural design is reused when designing the system architecture. The deployment restrictions are employed to determine valid deployment scenarios for an application. During run-time the same restrictions are at first used to automatically map additional services on suitable nodes. If node crashes are detected, we secondly employ the restrictions to guide the self-repair of the system in such a way that only suitable repair decisions are made.