Introduction to System Analysis and Design
29.1 INTRODUCTION Systems are created to solve problems. One can think of the systems approach as an organized way of dealing with a problem. In this dynamic world, The subject System Analysis and Design, mainly deals with the software development activities. 29.2 OBJECTIVES After going through this lesson, you should be able to: • • • •
understand a system understand the different phases of system developments life cycle know the components of system analysis know the components of system designing
29.3 Defining A System A collection of components that work together to realize some objective forms a system. Basically there are three major components in every system, namely input, processing and output.
In a system the different components are connected with each other and they are interdependent. For example, Human body represents a complete natural system. We are also bound by many national systems such as political system, economic system, educational system and so forth. The objective of the system demand that some output is produced as a result of processing the suitable inputs. 29.4 SYSTEM LIFE CYCLE System life cycle is an organisational process of developing and maintaining systems. It helps in establishing a system project plan, because it gives overall list of processes and sub-processes required developing a system.
System development life cycle means combination of various activities. In other words we can say that various activities put together are referred as system development life cycle. In the System Analysis and Design terminology, the system development life cycle means software development life cycle. Following are the different phases of software development cycle: • • • • • • • •
System study Feasibility study System analysis System design Coding Testing Implementation Maintenance
The different phases of software development life cycle is shown in Fig.29.1
Fig. 29.1 Different phases of Software development Life Cycle
29.5 PHASES OF SYSTEM DEVELOPMENT LIFE CYCLE Let us now describe the different phases and the related activities of system development life cycle in detail. (a) System Study
System study is the first stage of system development life cycle. This gives a clear picture of what actually the physical system is? In practice, the system study is done in two phases. In the first phase, the preliminary survey of the system is done which helps in identifying the scope of the system. The second phase of the system study is more detailed and in-depth study in which the identification of user’s requirement and the limitations and problems of the present system are studied. After completing the system study, a system proposal is prepared by the System Analyst (who studies the system) and placed before the user. The proposed system contains the findings of the present system and recommendations to overcome the limitations and problems of the present system in the light of the user’s requirements. To describe the system study phase more analytically, we would say that system study phase passes through the following steps: • • •
problem identification and project initiation background analysis inference or findings
(b) Feasibility Study On the basis of result of the initial study, feasibility study takes place. The feasibility study is basically the test of the proposed system in the light of its workability, meeting user’s requirements, effective use of resources and .of course, the cost effectiveness. The main goal of feasibility study is not to solve the problem but to achieve the scope. In the process of feasibility study, the cost and benefits are estimated with greater accuracy. (c) System Analysis Assuming that a new system is to be developed, the next phase is system analysis. Analysis involved a detailed study of the current system, leading to specifications of a new system. Analysis is a detailed study...