CIBM- Business InformationSystemsChapter Ten Systems Design andDevelopment
10.2.1 Systems Development• Systems development is a problem-solving process of investigating a situation; designing a system solution to improve the situation; acquiring the human, financial, and technological resources to implement the solution; and finally evaluating the success of the solution.• After a steering committee determines that a proposed project is desirable, a project team of end users and systems analysts is formed to develop the system. An end user is a person who will use the information system or the information it provides. A systems analyst is the IT professional who develops the system.
10.2.2 The Systems DevelopmentLife Cycle• An information system has a systems development life cycle (SDLC)—a sequence of steps or phases it passes through between the time the system is conceived and the time it is phased out. The phases of the systems life cycle include: investigation, analysis, design, development, implementation, maintenance, and retirement.
Investigation• System investigation involves defining the problem— identifying the information needs of the organization, examining the current system, determining how well it meets the needs of the organization, and studying the feasibility of changing or replacing the current system.• After completing the initial investigation of the problem, a systems analyst produces a feasibility study to help management decide whether to continue with the system analysis. Types of feasibility are:• Technical.• Economic.• Operational.• Organizational.
Analysis• During the analysis phase, the systems analyst gathers documents, interviews users of the current system (if one exists), observes the system in action, and generally gathers and analyses data to help understand the current system and identify new requirements. The systems analyst identifies the requirements related to each subsystem of the proposed system:• Input/output requirements.• Processing requirements.• Storage requirements.• Control requirements.
Design• The investigation phase focuses on why, the analysis phase focuses on what, and the design phase focuses on how. The systems analyst considers important how-to questions in three categories:• User interface design.• Database design.• Process design.• In many cases, the design phase produces a prototype system—a limited working system or subsystem to give the users and management an idea of how the completed system will work. With prototyping, the systems analyst can modify the prototype until it meets the needs and expectations of the organization.
Development• After the design is completed, the actual system development can begin. A large part of the development schedule is devoted to testing the system. Members of the system development team perform early testing to locate and eliminate bugs. This initial testing is known as alpha testing. Later, potential users who are willing to work with almost-finished software perform public beta testing and report bugs to the developers.
Implementation• When the testing is completed and known bugs have been eradicated, the new system is ready to replace the old one. In some cases, the new system is run in parallel with the old system until the analyst is confident that the new system is stable and reliable.• The systems analyst can choose one of four approaches for converting to the new system:• Direct cutover.• Parallel systems approach.• Phase-in approach.• Pilot approach.
Maintenance• The maintenance phase involves evaluating, repairing, and enhancing the system. For large custom systems, maintenance involves a continual process of evaluating and adjusting the system to meet organizational needs. In either case, maintenance usually lasts throughout the lifetime of the system.
Retirement• At some point in the life of a system, ongoing maintenance isn’t enough. Because of changes in organizational needs, user expectations, available technology, and other factors, the system no longer meets the needs of the users or the organization. At that point, it’s time to phase it out in favour of a newer system and begin another round of the system life cycle.