Software engineering for self-adaptive systems:research challenges in the provision of assurances

The important concern for modern software systems is to become more cost-effective, while being versatile, flexible, resilient, dependable, energy-efficient, customisable, configurable and self-optimising when reacting to run-time changes that may occur within the system itself, its environment or requirements. One of the most promising approaches to achieving such properties is to equip software systems with self-managing capabilities using self-adaptation mechanisms. Despite recent advances in this area, one key aspect of self-adaptive systems that remains to be tackled in depth is the provision of assurances, i.e., the collection, analysis and synthesis of evidence that the system satisfies its stated functional and non-functional requirements during its operation in the presence of self-adaptation. The provision of assurances for self-adaptive systems is challenging since run-time changes introduce a high degree of uncertainty. This paper on research challenges complements previous roadmap papers on software engineering for self-adaptive systems covering a different set of topics, which are related to assurances, namely, perpetual assurances, composition and decomposition of assurances, and assurances obtained from control theory. This research challenges paper is one of the many results of the Dagstuhl Seminar 13511 on Software Engineering for Self-Adaptive Systems: Assurances which took place in December 2013

The Reflective State Pattern

This paper presents the Reflective State pattern that is a refinement of the State design pattern [GHJV95] based on the Reflection architectural pattern [BMRS+96]. This pattern proposes a solution for some design decisions that have to be taken in order to implement the State pattern, such as the creation and the control of State objects and the execution of state transitions. When the object has a complex dynamic behavior, its implementation can also become very complex. The Reflective State pattern implements the control aspects in the meta level, separating them from the functional aspects that are implemented by the Context object and the State objects located at the base level. This pattern provides a solution that is easier to understand, extend and reuse than the State pattern. 2 Introduction The State design pattern[GHJV95] is a well known pattern that has been used in various applications[JZ91] [Rub94]. Its purpose is to allow an object to change its behavior when its intern..