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4.7 Requirements management 113

Identified Revised
Problem Problem Analysis and Change Analysis Change Requirements
Change Specification and Costing Implementation

1. Requirements identification Each requirement must be uniquely identified so
Figure 4.18
Requirements change that it can be cross-referenced with other requirements and used in traceability
management assessments.
2. A change management process This is the set of activities that assess the impact
and cost of changes. I discuss this process in more detail in the following section.
3. Traceability policies These policies define the relationships between each require-
ment and between the requirements and the system design that should be recorded.
The traceability policy should also define how these records should be maintained.
4. Tool support Requirements management involves the processing of large amounts
of information about the requirements. Tools that may be used range from specialist
requirements management systems to spreadsheets and simple database systems.

Requirements management needs automated support and the software tools for
this should be chosen during the planning phase. You need tool support for:

1. Requirements storage The requirements should be maintained in a secure, man-
aged data store that is accessible to everyone involved in the requirements engi-
neering process.
2. Change management The process of change management (Figure 4.18) is sim-
plified if active tool support is available.
3. Traceability management As discussed above, tool support for traceability
allows related requirements to be discovered. Some tools are available which
use natural language processing techniques to help discover possible relation-
ships between requirements.

For small systems, it may not be necessary to use specialized requirements man-
agement tools. The requirements management process may be supported using the
facilities available in word processors, spreadsheets, and PC databases. However,
for larger systems, more specialized tool support is required. I have included links
to information about requirements management tools in the book’s web pages.

4.7.2 Requirements change management

Requirements change management (Figure 4.18) should be applied to all proposed
changes to a system’s requirements after the requirements document has been approved.
Change management is essential because you need to decide if the benefits of imple-
menting new requirements are justified by the costs of implementation. The advantage of