Superimposition: a component adaptation technique

Several authors have identified that the only feasible way to increase productivity in software construction is to reuse existing software. To achieve this, component-based software development is one of the more promising approaches. However, traditional research in component-oriented programming often assumes that components are reused “as-is”. Practitioners have found that “as-is” reuse seldomly occurs and that reusable components generally need to be adapted to match the system requirements. Existing component object models provide only limited support for component adaptation, i.e. white-box techniques such as copy-paste and inheritance and black-box approaches such as aggregation and wrapping. These techniques suffer from problems related to reusability, efficiency, implementation overhead or the self problem. To address these problems, this paper proposes superimposition, a novel black-box adaptation technique that allows one to impose predefined, but configurable types of functionality on a reusable component. Three categories of typical adaptation types are discussed, related to the component interface, component composition and component monitoring. Superimposition and the types of component adaptation are exemplified by several examples.