HW11: Chapter 9

9.8 Briefly describe the three main types of software maintenance. Why is it sometimes difficult to distinguish between them?

Fault repairs to fix bugs and vulnerabilities: This type of maintenance involves correcting coding, design, or requirements errors. Coding errors are the cheapest to fix, followed by design errors, which may involve rewriting several program components. The most costly of all are requirements errors, which may involve extensive system redesign.

Environmental adaptation to adapt the software to new platforms and environments: This type of software maintenance involves modifying application systems to cope with changes to some aspect of the environment such as the database or the platform operating system.

Functionality addition to add new features and to support new requirements: This type of software maintenance involves adapting the software to changes to system requirements resulting from changes to organizational or business change. This is often the most time and effort-intensive type of maintenance.

One of the reasons it becomes difficult to distinguish between these types of maintenance is the overlap between them - they often occur concurrently. For example, you could run into and proceed to fix faults in the software as you are adapting it to new requirements and features. Likewise, fixing a feature may result in adding a whole new one to accommodate the necessary changes. Additionally, these types of maintenance have alternative names that can confuse people such as “corrective”, “adaptive”, and “perfective”.

9.10 Do software engineers have professional responsibility to develop code that can be easily maintained even if their employer does not explicitly request it?

They certainly do. Developing code that can be easily maintained is best software engineering practice as most code needs to be maintained regularly, especially that of a dynamic company.

It’s only in the software engineers’ best interest, anyway. If they plan to work somewhere long-term, developing difficult-to-maintain code will shoot them in the foot when a fault surfaces or a new feature needs to be added down the line. If they regularly spend extra time and effort maintaining code, there is no way they are reaching anywhere near their full efficiency potential. Hence, habitually developing difficult-to-maintain code means that the engineer is not fulfilling his/her professional duty to work as efficiently as possible. This may cause the employer to feel that the money they are paying the professional is going to waste.

Overall, it’s in their best interest in every way and common courtesy to fellow developers who may need to maintain the code. A little bit of extra time and effort up-front will pay dividends in time and effort maintaining the code later on.

• 2021 11
• 2020 22