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building a data model), which further requires and expands on the requirements and
ultimately lead to design [13].
2.2.2.1 System requirements
The terms system requirement refer to all of the capabilities and constraints that the new
system must meet. Generally analysts divide system requirements into two categories:
functional and nonfunctional requirements.
Functional
requirements
are
the
activitie s
that
the
system
must
perform
-
that
is,
the
business uses to which the system will be applied. For example, if you are developing a
payroll system, the required business uses might include functions such as “write
paychecks,” “calculate commission amounts,”
“calculate
payroll
taxes”,
“maintain
employee-dependent
information,”
and
“report
year-end tax deduction to
the IRS”.
The
new system must handle all these functions [14].
Nonfunctional
requirements
refer
to
behavioral
properties
that
the
system
must
have,
such as performance and usability.
Notice that the nonfunctional requirements describe a variety of
characteristic regarding
the system: operational, performance, security, and cultural and political. These
characteristics do not describe business process
or
information,
but
they
are
very
important in understanding what the final system would be like [13].
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