Classification on Composition and Interoperation

Object-oriented programming supports the reuse of software because classes can be extended and modified without direct changes to the original class. Additionally, objects act as independent and inter- active components. If we build software systems by combining predefined objects we have to consider composition and interoperation mechanisms used by their classes. We suggest a classification of composition and interoperation mechanisms. We distingiush levels of composition of components with data, user, and program interfaces. Interoperation is distinguished according to control and data interaction. This results in composition levels and a matrix of interoperation mechanisms that are presented as posters and (hopefully) serve as a basis for frutiful discussion on that subject.