1
Requirements definition
A “requirements definition” clarifies the function, performance, and content required of the system and software, and includes a “system requirements definition” and a “software requirements definition.” The demands of the user (system user department) are surveyed/analyzed to determine whether they are technologically feasible, and the requirements for
achieving the demands are then defined in detail.
This is the first step in system design, which plays a critical role in determining the success or failure of the subsequent system.
In order to develop a better system, the requirements are defined in cooperation with the various departments that will use the system.
2
System design
Development technology
●Software requirements definition
In a “software requirements definition,” the required software content is
specified on the basis of the actual business content.
In general, details such as the system interface, operability, functions required for business, operation, and maintenance are stipulated. At such
time, hearings are conducted with the users (system user department) in
order to gather as many opinions as possible, although it is also necessary
to analyze/consider whether those requirements can be realized.
Chapter 4
●System requirements definition
In a “system requirements definition,” the types of functions that are required for computerization are clearly stipulated.
In general, factors that determine system reliability such as operating conditions, security performance, and hardware used are stipulated. Accordingly, it is necessary to set priorities in order to maximize results within a
limited budget, and determine whether the content described in the system
requirements definition is worth the cost.
The system is designed based on the requirements definition.
The procedure for designing a system is summarized below.
Systems architecture
design (External design)
The user (system user department) designs the
components of the system that can be seen from the
outside.
Software architecture
design (Internal design)
The system development department designs the
internal functions required by the system in order to
realize the functions determined in the system
architecture design.
Software detailed design
(Program design)
The system development department designs the internal
structure of the programs based on the software
architecture design.
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