What are the strategic options for legacy system evolution?

What are the strategic options for legacy system evolution?
Answer: There are four strategic options:

1. Scrap the system completely: This option should be chosen when the system is not making an effective contribution to business processes. This commonly occurs when business processes have changed since the system was installed and are no longer reliant on the legacy system.

2. Leave the system unchanged and continue with regular maintenance: This option should be chosen when the system is still required but is fairly stable and the system users make relatively few change requests.

3. Reengineer the system to improve its maintainability: This option should be chosen when the system quality has been degraded by change and where a new change to the system is still being proposed. This process may include developing new interface components so that the original system can work with other, newer systems.

4. Replace all or part of the system with a new system: This option should be chosen when factors, such as new hardware, mean that the old system cannot continue in operation or where off-the-shelf systems would allow the new system to be developed at a reasonable cost. In many cases, an evolutionary replacement strategy can be adopted in which major system components are replaced by off-the- shelf systems with other components reused wherever possible.