Software Evolvability by Component-Orientation

Software is often in a state of flux because of inaccurate or incomplete requirements at development time or due to changing needs during the life cycle. Component-orientation structures software systems in compartments which localise the impact of requirement changes, simplifying replacement of subsystems if the need arises. Unfortunately, current technologies focus on the initial construction phase, disregarding software evolvability aspects. Although the number of compartments affected by requirement changes is usually small, rather tight coupling between components complicates and in certain circumstances even prevents evolvability. This paper introduces a loosely coupled component model whose communication scheme is based on arbitrarily interleavable message propagation scopes which define and constrain the "connectedness" of software components. Inspired by biological concepts, namely principles of signal transmission at cell level and communication mechanisms of higher order organisms, analogies between biological components and software components which help to increase adaptability and flexibility are drawn. Finally, the model's benefits within the context of COMDECO are sketched to give an impression of its practical applicability