Requirements Analysis - Requirements Engineering and Management for Software Development Projects - page 60

software design phase. We need to carry out this assessment for each of the
requirements until all requirements are neatly grouped into their logical groups.
Group Ancillary Functionality Requirements into Their Logical Groups—
The ancillary functionality requirements are enumerated in Chap. 2 . While all core
functionality requirements can be designed by one class of designers, all ancillary
functionality requirements cannot be designed by one class of designers. Some of
the ancillary functionality requirements such as security requirements, and
usability requirements would need a different class of designers. Therefore, it is
necessary to group ancillary functionality requirements into their logical groups to
facilitate better software design.
Identify Requirements that are Duplicated—Especially in large projects
wherein requirements are collected from multiple agencies, it is possible that
stated requirements are duplicated. We need to eliminate the duplicated require-
ments so that design effort is not wasted. This can be easily achieved if we had
followed requirements description conventions suggested in an earlier section. We
can sort the requirements by the ''Requirement Description'', second column of
Table 4.1 . We can examine if any requirements are duplicated and if any such
duplication is uncovered, we can easily eliminate such duplication. This step is in
fact a cleansing step that provides us unique requirements.
Identify Requirements that are Contradictory to each Other—This step is
also a cleansing step but is not as easy as locating duplicate requirements. If we
have contradictory requirements and allow them to slip through design and con-
struction, we would have a software product that provides unpredictable/unreliable
results. To identify contradictory requirements, we need to study each of the
requirements; understand it in the right perspective and then see if any other
requirement is contradicting the one at hand. The following tips would help in
identifying contradictory requirements:
1. When requirements for the same function are collected from two or more
workstations, we are likely to receive contradictory requirements. When
looking for contradictory requirements, we need to look into the requirements
specified for the same function by different individuals.
2. It is likely to have contradiction between the perceptions of the person per-
forming a function and the individuals providing inputs or receiving outputs
from that function. So, we need to look closely at the requirements specified by
the individual performing a function and the persons providing inputs to that
function or receiving outputs from that function.
3. There is also a possibility of contradiction in the perceptions of the person
performing a function and his supervisor. It is more likely to be so if the length
of experience of these two individuals varies significantly. That is, one of them
is new to the function and the other is much more senior. To identify contra-
dictory requirements, we also need to look closely at the information provided
by the person performing the function as well as the person to whom he/she is
reporting to.