9.8 > Briefly describe the three main types of software maintenance. Why is it sometimes difficult to distinguish between them?
- Bug Fixing - this is repairing faults found in the software after it has been launched. The bugs are there possibly because testing was not as thorough as it should have been or clients have exposed bugs by using the software in unexpected ways. Coding errors, design errors, and requirement errors are the least, middle, and most expensive to correct, respectively.
- Modifying software to work in a new environment - when the hardware or platform that the system was built to run on changes, then the software must change as well in order to be compatible and avoid being obsolete.
- Implementing new or changed requirements - software must be updated or changed so that it conforms with any new requirements.
It is sometimes difficult to distinguish between the different types of maintenance because they are often given different names and also because faults that arise within a system can maybe have overlapping maintenance requirements.
9.10 > Do software engineers have a professional responsibility to develop code that can be easily maintained even if their employer does not explicitly request it?
Yes definitely! Software development and maintenance are not separate activities. It is important to keep in mind how a system will need to be maintained if, for example, it is a system that is meant to last a long time and will have a revolving-door of developers working on it. A software developer who cares about the quality of their work will want to reduce the future cost of maintaining their software. According to the textbook, they can do this by using "Good software engineering techniques such as precise specification, test-first development, the use of object-oriented development, and configuration management" to help reduce the cost of future maintenance (Sommerville 259). The ACM Software Engineering Code of Ethics says that a software engineer must "promote an ethical approach to the practice of the profession". This can only by done by carefully constructing software that is in the best interests of the employer (even if they do not require it), the client (who will have to pay for future maintenance), and the public (who want to use the software).