On the challenges of self-adaptation in systems of systems

A system of systems (SoS) integrates independently useful systems into a larger system. Examples are integrated surveillance systems and networked smart homes. A SoS offers functions to users that cannot be provided by its individual parts, but emerge as a combination of these. However, providing these functions with a required level of quality is difficult due to inherent uncertainties, such as systems that attach and detach at will and faults that are difficult to predict. Self-adaptation is a well-studied approach that enables a system to reason about itself and adapt to achieve particular quality objectives in the face of uncertainties and change. However, the inherently decentralized nature of SoS raises fundamental challenges to self-adaptation. This paper presents three architectural styles to realize self-adaptation in SoS, discusses key challenges for each style, and outlines starting points that could help to tackle these challenges.