Requirements management planning

Planning is an essential first stage in the requirements management process.
Requirements management is very expensive. For each project, the planning stage
establishes the level of requirements management detail that is required. During the
requirements management stage, you have to decide on:
1. Requirements identification Each requirement must be uniquely identified so
that it can be cross-referenced by other requirements and so that it may be used
in traceability 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 requirements,
and between the requirements and the system design that should be
recorded and how these records should be maintained.
4. CASE tool support Requirements management involves the processing of large
amounts of infonnation about the requirements. Tools that may be used range
from specialist requirements management systems to spreadsheets and simple
database systems.
There are many relationships among requirements and between the requirements
and the system design. There are also links between requirements and the underlying
reasons why these requirements were proposed. When changes are proposed,
you have to trace the impact of these changes on other requirements and the system
design. Traceability is the property of a requirements specification that reflects
the ease of finding related requirements.
There are three types of traceability infonnation that may be maintained:
1. Source traceability infonnation links the requirements to the stakeholders who
proposed the requirements and to the rationale for these requirements. When a
change is proposed, you use this infonnation to find and consult the stakeholders
about the change.
2. Requirements traceability infonnation links dependent requirements within the
requirements document. You use this infonnation to assess how many requirements
are likely to be affected by a proposed change and the extent of consequential
requirements changes that may be necessary.
3. Design traceability infonnation links the requirements to the design modules
where these requirements are implemented. You use this infonnation to assess
the impact of proposed requirements changes on the system design and implementation.
Traceability infonnation is often represented using traceability matrices, which
relate requirements to stakeholders, each other or design modules. In a requirements
traceability matrix, each requirement is entered in a row and in a column in the
matrix. Where dependencies between different requirements exist, these are
recorded in the cell at the row/column intersection.
Requirements management needs automated support; the CASE tools for this should
be chosf:n during the planning phase. You need tool support for:
l. Requirements storage The requirements should be maintained in a secure, managed
data store that is accessible to everyone involved in the requirements engineering
process.
2. Change management The process of change management (Figure 7.13) is simplified
if active tool support is available.
3. Traceability management As discussed above, tC101 support for traceability allows
related requirements to be discovered. Some Itools use natural language processing
techniques to help you discover possible relationships between the
requirements..
For small systems, it may not be necessary to use specialised requirements management
tools. The requirements management process may be supported using the
facilities availablt: in word processors, spreadsheet.s and PC databases. However,
for larger systems, more specialised tool support is required. I have included links
to infonnation about requirements management tools such as DOORS and
Requisitf:Pro in the book's web pages.