7. Maintaining software solutions

Question 1

Define Maintainability

Answer 1

A measure of the ease with which source code can be understood and modified

Question 2

Changing user requirements

Answer 2

Modifying code to include new functionality due to change in users’ requirements

Question 3

Upgrading the user interface

Answer 3

The user interface is often the most significant influence on the ongoing success of a software product. Changes to the user interface can cause problems for users skilled in the use of the existing product. Care must be taken to maintain consistency between subsequent versions of software products. It is significantly preferable for user interfaces to evolve without significantly altering their structure.

Question 4

Changes in the data to be processed

Answer 4

Modifications to software are often required when the structure or format of the input data changes

Question 5

Introduction of new hardware or software

Answer 5

Software developers must modify their products if they wish to use new features of hardware

Question 6

Changing organisational focus

Answer 6

Software applications often require modification to cater to the changes in organisations. Custom designed solutions often require continual modification.

Question 7

Changes in government requirements

Answer 7

Government legislation covers many areas that can affect software applications. As legislation and laws are changed by government these software applications must be modified to comply.

Question 8

Poorly implemented code

Answer 8

Testing and evaluating software solutions aims to ensure that software applications are bug free and perform their tasks efficiently. Maintenance is required to correct problems as they are discovered.

Question 9

Define plagiarism

Answer 9

Copying or imitating the work of another and claiming it to be your own

Question 10

Use of variables or constants instead of literal constants

Answer 10

Programmers overcame the problem of replacing every occurrence of a value by assigning literal constants to variables.

Question 11

Meaningful names for variables

Answer 11

Meaningful variable names greatly increases the readability and hence the maintainability of source code. Meaningful identifiers should also be used for subroutines. Code that uses meaningful identifiers is said to be self-documenting.

Question 12

Explanatory comments in the code

Answer 12

Comments within the source code should explain what the code does rather than how it does it. Comments that describe the detail of the processing will be incorrect if the processing is altered. Comments should also be used to document changes made to the code.

Question 13

A clear and uncluttered mainline

Answer 13

The mainline or main program of a software solution should include minimal actual processing. The mainline of many programs will essentially be a series of calls to subroutines.

Question 14

One logical task per subroutine

Answer 14

Subroutines that accomplish a single logical task increase the maintainability of the product. The longer the subroutine is, the more difficult it will be to understand, test, and subsequently maintain. Short routines that accomplish single, well-defined tasks are generally easier to understand, test, reuse and consequently maintain.

Question 15

Documentation to the user

Answer 15

Before modifying a product, it is important that the developers understand the operation of the existing product from the user’s perspective. Types of user documentation include installation guides, user manuals, reference manuals, online help and tutorials.

Question 16

Documentation to the developer

Answer 16

The source code itself is the most crucial piece of documentation when modifying software solutions. Other forms of technical documentation, that were produced during the product’s design and development, will also be of assistance when attempting to understand and interpret code in preparation for modification. Types of technical documentation in addition to the source code include requirements, design specifications; system models, system flowcharts, data flow diagrams, structure charts; IPO charts; data dictionaries; algorithms and screen designs and storyboards.