From Software Systems to Complex Software Ecosystems: Model- and Constraint-Based Engineering of Ecosystems

Software is not self-supporting. It is executed by hardware and interacts with its environment. So-called software systems are complicated hierarchical systems. They are carefully engineered by competent engineers. In contrast, complex systems, like biological ecosystems, railway systems and the Internet itself, have never been developed and tested as a whole by a team of engineers. Nevertheless, those complex systems have the ability to evolve without explicit control by anyone, and they are more robust to dealing with problems at the level of their constituent elements than classical engineered systems. Consequently, in this article we introduce the concept of complex software ecosystems comprised of interacting adaptive software systems and human beings. Ecosystems achieve the demanded flexibility and dependability by means of a kind of higher-level regulatory system. Their equilibrium is continuously preserved through the appropriate balance between the self-adaptation and the self-control capabilities of an ecosystem’s participants.