Adaptive systems respond to changes in their internal state or external environment with guidance from an underlying control system. ULS systems are particularly likely to re- quire dynamic adaptation because of their decentralized con- trol and the large number of independent stakeholders whose actions are integral to the system"s behavior. Adaptation may take various forms, but the system structure will al- most inevitably include one or more closed feedback loops. We argue that adaptability is a characteristic of a solution, not of a problem, and that the feedback loop governing con- trol of adaptability should be explicit in design and analysis and either explicit or clearly traceable in implementation.

Preferred citation: Visibility of Control in Adaptive Systems, Hausi Müller, Mauro Pezzè, and Mary ShawSecond International Workshop on Ultra-Large-Scale Software-Intensive Systems (ULSSIS 2008), at the International Conference on Software Engineering (ICSE 2008), Leipzig, Germany, May 2008, Pages 23-26