8.4.2 Enabling Changes in Systems throughout the Entire Life-Cycle – Key to Success ?

In the past decades the world has been changing in almost every aspect. Systems development is facing rapidly changing and increasingly global environments in markets, competition, technology, regulatory and societal systems. Systems to be delivered must be designed not only to meet customer or market needs, but increasingly to meet requirements and constraints of systems sharing its operational context and throughout their entire lifecycle. The design of a system must provide for a continuous evolution of its architecture either by upgrading a system already in service or releasing a new version. Based on these key challenges imosed on development systems, this paper will evolve the idea of incorporating changeability into a systems architecture. Flexibility, agility, robustness, and adaptability as four key aspects of changeability will be defined and described. Design principles to enable flexibility, agility, robustness, and adaptability within integrated systems are proposed and described. A measurement of a degree of implementation of certain aspects of changeability as well as cost associated with it are addressed with metrics. A basic process outlining and guiding an application of the framework described concludes this paper. Examples from varying industries will illustrate the applicability and implementation of selected principles. Thus this paper spans a view from why, when and where, what, and how changeability has to be incorporated into a systems architecture.