The staged model of the software lifecycle: A new perspective on software evolution

In the conventional view of the software life cycle, software is produced, delivered to the user, and then enters a maintenance stage. Maintenance is the more expensive and extensive activity, and many surveys exist that analyze it in terms of constituent activities such as corrective, perfective, adaptive maintenance, etc. In this paper, we suggest a different view that partitions the conventional maintenance phase in a more useful, relevant and constructive way. We retain initial development, but then propose an explicit evolution stage. Next is a service stage, consisting of simple tactical activities. Later still, the software moves to a phase-out stage and finally to a close-down. The key point is that software evolution is quite different and separate from servicing, from phase-out, and from close-down, and this distinction is crucial in clarifying both the technical and business consequences. This perspective, by adopting both technical and business roles, is useful in planning and stimulates a set of research issues.