Deriving Available Behavior All Out from Incompatible Component Compositions

In component-based software development, an important problem is behavioral incompatibility in component compositions. That two components are behaviorally incompatible means that they cannot work together due to the mismatching order of exchanged messages between them. One of the approaches to solving this problem is to construct an environment for the incompatibility components and make it possible that they can work together in the environment. In practice, if two components, particularly commercial off-the-shelf (COTS) components, are behaviorally incompatible, we usually desire that most of the useful behavior can be preserved all out from their composition rather than discard them simply. In this paper, we use interface automata to model the behavior of components, and present an approach to deriving available behavior all out from incompatible component compositions. The main idea of the approach is to construct a comprehensive legal environment (CLE) such that two incompatible components can work together and the behavior of their composition can be preserved as much as possible. The principle of CLEs is to obviate the incompatible points of behavior, i.e. the states at which an input action provided by one component is not accepted by the other, to be reached in the composition by selecting the appropriate input actions provided for the composition. We develop an algorithm to construct CLEs, and discuss the possible improvement for the algorithm.