TOPIC 3.5. PROGRAM MAINTENANCE

• All systems need to be maintained; that is performance monitored, modifications made if required, errors correct, documentation kept up-to-date.
• Alls programs require maintenance, and in fact the vast majority of programmers are employed to maintain existing programs rather than to write new ones.
• There are differing reasons for this, and different types of maintenance as below:

            (1) Perfective maintenance

            (2) Adaptive maintenance

            (3) Corrective maintenance

PERFECTIVE MAINTENANCE

• This maintenance implies that while the system runs satisfactorily, there is still room for improvement.
• For example, extra management information may be needed so that new report programs have to be written. Database queries may be very slow, and a change in a program may be able to improve response time.

ADAPTIVE MAINTENANCE

• All systems will need to adapt to changing needs within a company.
• As a business expands, for example, there may be a requirement to convert a standalone system to a multi-user system.
• New and better hardware may become available, and changes to the software may be necessary to take advantage of this.
• Competition from other firms may mean that systems have to be upgraded in order to maintain a competitive edge.

CORRECTIVE MAINTENANCE

• Problems frequently surface after a system has been in use for a short time, however thoroughly it was tested.
• Some part of the system may not function as expected, or a report might be wrong in some way; total missing at the bottom, incorrect sequence of data, wrong headings, etc.
• Frequently errors will be hard to trace, if for example a file appears to have been wrongly updated.

RESOURCE:

P M Heatcote, [A level Computing, 3rd Edition], Ashford Colour Press Ltd, 1996.