System Development Life Cycle Method
It is a step-by-step, structured process for the development of a system. This process draws upon the engineering approach to the analysis and solution of complex problems. It is based upon the concept of a sequence of necessary activities through which systems must pass during the period of their creation and existence, or life cycle. Within the lifecycle, significant series of related activities are combined into phases, called the lifecycle phases. The concept of lifecycle has lead to the adoption of a project-oriented approach to the design and development of systems. This method is referred to as the life-cycle methodology, commonly referred to as the systems development life cycle, or SDLC.
System development life cycle is sometimes also referred to as system study. To understand system development, it has to be recognized that a system has a life cycle, just like a living system. In common the activities that must be executing throughout the systems development life cycle and the series in which they are performed are well identified and known. These stages are-
1. Recognition of need
2. Feasibility study
6. Post-implementation and maintenance
a) Recognition of need: One must know about what the problem is before it can be handled or solved. It could be improving or redesigning an existing system or procedure. For example, compiling a bibliography on a topic would involve scanning periodicals for collecting the references which is time consuming. An alternative could be to build a database that can solve the problem of time delay. An analyst's first task is to prepare a statement specifying the scope and objective of the problem. At this stage, only a rough estimate of the development cost of the project may be reached.
b) Feasibility study: Based on the statement of scope and objective of the problem, a more detailed study is conducted. The feasibility study is the test of a system proposal on the basis of its workability, ability to meet user needs, impact on the organization, and effective use of resources. The objective of the feasibility is not to solve the problem but to acquire a sense of its scope. During the study, problem definition is crystallized and aspects of the problem to be included in the system are determined. As a result, costs and benefits are expected with greater accurateness at this stage.
The consequence of the feasibility study is a formal proposal. The proposal sums up what is recognized and what is going to be done. It consists of statement of the problem, summary of findings and recommendations, details of findings, and recommendations and conclusions. After the proposal is analyzed by the management, it turns out to be a formal agreement that paves the way for concrete design and implementation.
c) Analysis: Analysis is a thorough study of the diverse operations done by a system and their relationships inside and outside the system. During analysis, data are accumulated on the decision points, available files, and transactions handled by the present system. Data flow diagrams, interviews, on-site observations, and questionnaires are tools used collect data and information. Once analysis is finished, the analyst has a firm understanding that what is to be done. The next step is to make a decision on how the problem might be solved.
d) Design: The word design explains a ultimate system and the process by which it is developed. It refers to technical specifications that will be applied to implementing the candidate system. It also contains the creation of programs and program testing.
The first step in system design is to determine who the output is to be produced and in what format. Samples of the output (and input) are also accessible. Second, input data and master files (data base) have to be designed to meet the requirements of the output. The operational (processing) phase handled through program construction and testing, including a list of the programs needed to meet the system's objectives and complete documentation. At last, details linked to justification of the system and an approximation of the impact of the candidate system on the user and the organization are documented and analyzed by management as a step ahead for implementation.
e) Implementation: The implementation stage is concerned with user training, site preparation, and file conversion. During the last testing, user approval is tested, followed by training. Conversion generally occurs at approximately the same time the user is being trained or later. System testing checks the readiness and accuracy of the system to access, updates, and retrieve data from new files. Once the programs become accessible, test data are study into the computer and processed against the files given for testing. If successful, the program(s) is then run with actual data. The new system runs simultaneously with the "old" system to enables the staff to gain experience and learn the new system.
f) Post-implementation and maintenance: For the successful and trouble free working of the system periodic maintenance of hardware and software is carried out.
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