Information Technology Reference
In-Depth Information
Fig. 9.1 Software life cycle
model (Raymond
2003
)
Requirements
Testing
Design
Implementation
9.1.1 Implementation Standards
Implementation is the process of translating the detailed design into code. When
this is done by a single individual, the process is relatively well understood. But,
most real-life products today are too large to be implemented by one programmer
within the given time constraints (Schach
2007
). Code is produced from the de-
liverables of the design phase during implementation, and this is the longest phase
of the software development life cycle. For a developer, this is the main focus of
the life cycle because this is where the code is produced. Implementation may
overlap with both the design and testing phases. Many tools exists (CASE tools) to
actually automate the production of code using information gathered and produced
during the design phase. Figure
9.1
shows the general life cycle model including
the implementation phase.
In the implementation phase, the system or system modifications are installed
and made operational in a production environment. Activities in this phase include
notification of implementation to end users, execution of the previously defined
training plan, data entry or conversion and post implementation review. This phase
continues until the system is operating in production, and is in accordance with the
defined user requirements. The new system can fall into three categories,
replacement of a manual process, replacement of a legacy system, or upgrade to an
existing system. Regardless of the type of system, all aspects of the implemen-
tation phase should be followed. This will ensure the smoothest possible transition
to the organization's desired goal.
Implementation standards should be in place to address the responsibilities of
application and system programmers. Application programmers are responsible for
developing and maintaining end-user applications. System programmers are
responsible for developing and maintaining internal and open-source operating
system programs that link application programs to system software and subse-
quently to hardware. Managers should thoroughly understand development and
production
environments
to
ensure
they
appropriately
assign
programmer
responsibilities.
Implementation standards should prohibit a programmer's access to data,
programs, utilities and systems outside their individual responsibilities. Library
controls can be used to manage access to, and the movement of programs between,
implementation, testing and production environments. Management should also
establish standards requiring programmers to document completed programs and
test results thoroughly. Appropriate documentation enhances a programmer's
ability to correct programming errors and modify production programs.
Coding standards, which address issues such as the selection of programming
languages and tools, the layout or format of scripted code and the naming con-
ventions of code routines and program libraries, are outside the scope of this
