Cooperating evolving components- A rigorous approach to evolving large software systems

Large software systems have a large number of components and are developed over a long time period frequently by a large number of people. We describe a framework approach to evolving such systems based on an integration of product and process modelling. The evolving system is represented as a Product Tower, a hierarchy of components which provides views of the product at multiple levels of refinement. The evolution process is component based with the cooperation between components being mediated by the Product Tower. This ensures that the evolution process is scaleable and that it maintains, and evolves, the design model. We illustrate our approach with an example, outlining an evolution both of the product and of the process. The reflexive facilities of the process are shown to be key in ensuring the framework's ability to evolve.