Software evolution process includes the fundamental activities of change analysis, release planning, system implementation, and releasing a system to customers. The cost and impact of these changes are assessed to see how much of the system is affected by the change and how much it might cost to implement the change. If the proposed changes are accepted, a new release of the system is planned. During release planning, all proposed changes (fault repair, adaptation, and new functionality) are considered. A decision is then made on which changes to implement in the next version of the system. The changes are implemented and validated, and a new version of the system is released. The process then iterates with a new set of changes proposed for the next release.
In change implementation the revisions to the system are designed, implemented, and tested. However, a critical difference is that the first stage of change implementation may involve program understanding, especially if the original system developers are not responsible for change implementation. During this program understanding phase, you have to understand how the program is structured, how it delivers functionality, and how the proposed change might affect the program. You need this understanding to make sure that the implemented change does not cause new problems when it is introduced into the existing system.
During the evolution process, the requirements are analyzed in detail and implications of the changes emerge that were not apparent in the earlier change analysis process. This means that the proposed changes may be modified and further customer discussions may be required before they are implemented. Change requests sometimes relate to system problems that have to be tackled urgently.
