Information Technology Reference
In-Depth Information
to software components in the library. DTE's developers meet frequently to discuss ideas,
problems, and opportunities of using the library of reusable software components.
Chapter 4 discussed a number of programming languages that use the object-oriented
approach, including Visual Basic, C++, and Java. These languages allow systems developers
to take the OO approach, making program development faster and more efficient, resulting
in lower costs. Modules can be developed internally or obtained from an external source.
After a company has the programming modules, programmers and systems analysts can
modify them and integrate them with other modules to form new programs.
Object-oriented systems development (OOSD)
combines the logic of the systems de-
velopment life cycle with the power of object-oriented modeling and programming. OOSD
follows a defined systems development life cycle, much like the SDLC. The life cycle phases
are usually completed with many iterations. Object-oriented systems development typically
involves the following tasks:
•
object-oriented systems
development (OOSD)
An approach to systems
development that combines the
logic of the systems development
life cycle with the power of object-
oriented modeling and
programming.
Identifying potential problems and opportunities within the organization that would
be appropriate for the OO approach.
This process is similar to traditional systems
investigation. Ideally, these problems or opportunities should lend themselves to the
development of programs that can be built by modifying existing programming modules.
•
Defining what kind of system users require.
This analysis means defining all the objects
that are part of the user's work environment (object-oriented analysis). The OO team
must study the business and build a model of the objects that are part of the business
(such as a customer, an order, or a payment). Many of the CASE tools discussed in the
previous section can be used, starting with this step of OOSD.
•
Designing the system.
This process defines all the objects in the system and the ways
they interact (object-oriented design). Design involves developing logical and physical
models of the new system by adding details to the object model started in analysis.
•
Programming or modifying modules.
This implementation step takes the object model
begun during analysis and completed during design and turns it into a set of interacting
objects in a system. Object-oriented programming languages are designed to allow the
programmer to create classes of objects in the computer system that correspond to the
objects in the actual business process. Objects such as customer, order, and payment are
redefined as computer system objects—a customer screen, an order entry menu, or a
dollar sign icon. Programmers then write new modules or modify existing ones to produce
the desired programs.
•
Evaluation by users.
The initial implementation is evaluated by users and improved.
Additional scenarios and objects are added, and the cycle repeats. Finally, a complete,
tested, and approved system is available for use.
•
Periodic review and modification.
The completed and operational system is reviewed at
regular intervals and modified as necessary.
As discussed earlier in the chapter, systems investigation is the first phase in the traditional
SDLC of a new or modified business information system. The purpose is to identify potential
problems and opportunities and consider them in light of the goals of the company. In
general, systems investigation attempts to uncover answers to the following questions:
•
What primary problems might a new or enhanced system solve?
•
What opportunities might a new or enhanced system provide?
•
What new hardware, software, databases, telecommunications, personnel, or procedures
will improve an existing system or are required in a new system?
•
What are the potential costs (variable and fixed)?
•
What are the associated risks?
