section three :: system development
The systems approach can be
applied to the solution of many types of problems. However, when it
is applied to the development of information system solutions to business
problems, it is called information systems development or application
development. Most computer-based information systems are conceived,
designed, and implemented using some form of a systematic development
process. In this process, end users and information specialists design
information systems based on an analysis of the information requirements
of an organization. Thus, a major part of this process is known as
systems analysis and design. However, several other major activities
are involved in a complete development cycle.
 Beginning the development
System Investigation:Do we have a business
problem (or opportunity)? What is causing the problem? Would a new or
improved information system help solve the problem? What would be a
feasible information system solution to our problem? These are the questions
that have to be answered in the systems investigation stage-the first
step in the systems development process. This stage may involve consideration
of proposals generated by an information systems planning process. The
investigation stage includes the screening, selection, and preliminary
study of proposed information system solutions to business problems.
Systems Analysis :We need information of the system,
problems, options and consequences. Systems analysis traditionally involves
a detailed study of:
 Systems Implementation:Systems analysis describes
what a system should do to meet the information needs of users. Systems
design specifies how the system will accomplish this objective. Systems
design consists of design activities that produce system specifications
satisfying the functional requirements developed in the systems analysis
stage. User Interface Design and System Specifications (data
design + process design)
Other Implementation Issues:
Testing, documentation, and training are keys to successful implementation of a new system.
The initial operation of a new computer-based system can be a difficult task. Such an operation is usually a conversion process in which the personnel, procedures, equipment, input/output media, and databases of an old information system must be converted to the requirements of a new system. Four major forms of system conversion include: (1) Parallel conversion. (2) Phased conversion. (3) Pilot conversion. (4) Plunge or direct cutover.
Conversions can be done on a parallel basis, whereby both the old and the new systems are operated until the project development team and end user management agree to switch completely over to the new system. It is during this time that the operations and results of both systems are compared and evaluated. Errors can be identified and corrected, and the operating problems can be solved before the old system is abandoned. Installation can also be accomplished by a direct cutover or plunge to the newly developed system. It can also be done on a phased basis, where only parts of a new application or only a few departments, branch offices, or plant locations at a time are converted. A phased conversion allows a gradual implementation process to take place within an organization. Similar benefits accrue from using a pilot conversion, where one department or other work site serves as a test site. A new system can be tried out at this site until developers feel it can be implemented throughout the organization.
Once a system is fully implemented and being operated by end users, the maintenance function begins. Systems maintenance is the monitoring, evaluating, and modifying of operational information systems to make desirable or necessary improvements. For example, the implementation of a new system usually results in the phenomenon known as the learning curve. Personnel who operate and use the system will make mistakes simply because they are not familiar with it. Though such errors usually diminish as experience is gained with a new system, they do point out areas where a system may be improved. Maintenance is also necessary for other failures and problems that arise during the operation of a system. End users and information systems personnel then perform a troubleshooting function to determine the causes of and solutions to such problems.
The maintenance activity includes a post implementation review process to ensure that newly implemented systems meet the systems development objectives established for them. Errors in the development or use of a system must be corrected by the maintenance process. This includes a periodic review or audit of a system to ensure that it is operating properly and meeting its objectives. This audit is in addition to continually monitoring a new system for potential problems or necessary changes. Maintenance includes making modifications to a system due to changes in the business organization or the business environment. For example, new tax legislation, company reorganizations, and new business ventures usually require making a variety of changes to current business information systems.