Information Technology Reference
In-Depth Information
software, database, telecommunications, personnel, and procedure components; and shows
how these components are related.
Systems implementation
involves creating or acquiring
the various system components detailed in the systems design, assembling them, and plac-
train the users. Systems implementation results in an installed, operational information sys-
tem that meets the business needs for which it was developed. It can also involve phasing out
or removing old systems, which can be difficult for existing users, especially when the systems
are free. In 2005, Walt Disney developed the
Virtual Magic Kingdom (VMK)
game to cele-
offered virtual rewards to game players. When Disney decided to remove or terminate the
game, some players were outraged and protested outside Disney offices in California.
The purpose of
systems maintenance and review
is to ensure that the system operates
and to modify the system so that it continues to meet changing business needs. As shown in
Figure 12.6, a system under development moves from one phase of the traditional SDLC to
the next.
The traditional SDLC allows for a large degree of management control. However, a
major problem is that the user does not use the solution until the system is nearly complete.
Table 12.1 lists advantages and disadvantages of the traditional SDLC.
systems implementation
The systems development phase
involving the creation or acquisition
of various system components
detailed in the systems design,
assembling them, and placing the
new or modified system into
operation.
systems maintenance and
review
The systems development phase
that ensures the system operates
and modifies the system so that it
continues to meet changing
business needs.
Table 12.1
Advantages
Disadvantages
Advantages and Disadvantages
of Traditional SDLC
Formal review at the end of each
phase allows maximum
management control.
Users get a system that meets the needs as
understood by the developers; this might not
be what is really needed.
This approach creates considerable
system documentation.
Documentation is expensive and time consuming
to create. It is also difficult to keep current.
Formal documentation ensures that
system requirements can be traced
back to stated business needs.
Often, user needs go unstated or are
misunderstood.
It produces many intermediate
products that can be reviewed to
see whether they meet the users'
needs and conform to standards.
Users cannot easily review intermediate products
and evaluate whether a particular product
(e.g., data flow diagram) meets their business
requirements.
Prototyping
Prototyping
takes an iterative approach to the systems development process. During each
iteration, requirements and alternative solutions to the problem are identified and analyzed,
encouraged to try the prototype and provide feedback (see Figure 12.7). Prototyping begins
with creating a preliminary model of a major subsystem or a scaled-down version of the
entire system. For example, a prototype might show sample report formats and input screens.
After they are developed and refined, the prototypical reports and input screens are used as
models for the actual system, which can be developed using an end-user programming lan-
guage such as Visual Basic. The first preliminary model is refined to form the second- and
third-generation models, and so on until the complete system is developed (see Figure 12.8).
Prototypes can be classified as operational or nonoperational. An
operational prototype
is
a prototype that works—accesses real data files, edits input data, makes necessary computa-
tions and comparisons, and produces real output. A
nonoperational prototype
is a mock-up,
or model, that includes output and input specifications and formats. The advantages and
disadvantages of prototyping are summarized in Table 12.2.
