Stitch: A language for architecture-based self-adaptation

Requirements for high availability in computing systems today demand that systems be self-adaptive to maintain expected qualities-of-service in the presence of system faults, variable environmental conditions, and changing user requirements. Autonomic computing tackles the challenge of automating tasks that humans would otherwise have to perform to achieve this goal. However, existing approaches to autonomic computing lack the ability to capture routine human repair tasks in a way that takes into account the business context humans use in selecting an appropriate form of adaptation, while dealing with timing delays and uncertainties in outcome of repair actions. In this article, we present Stitch, a language for representing repair strategies within the context of an architecture-based self-adaptation framework. Stitch supports the explicit representation of repair decision trees together with the ability to express business objectives, allowing a self-adaptive system to select a strategy that has optimal utility in a given context, even in the presence of potential timing delays and outcome uncertainty.