Systems Analysis And Design PDF

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Systems Analysis and Design

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 of System Analysis and Design (SAD), mainly deals with software development activities.

Objectives

After going through this lesson, you should be able to l defines a system l explain the different phases of system development life cycle l enumerate the components of system analysis l explain the components of system designing

Defining A System

A collection of components that work together to realize some objectives 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, the human body represents a completely natural system.

We are also bound by many national systems such as the political system, economic system, educational system, and so forth.

The objective of the system demands that some output is produced as a result of processing the suitable inputs.

A well-designed system also includes an additional element referred to as ‘control’ that provides feedback to achieve desired objectives of the system.

SYSTEM LIFE CYCLE

The system life cycle is an organizational process of developing and maintaining systems. It helps in establishing a system project plan because it gives an overall list of processes and sub-processes required for developing a system.

System development life cycle means a combination of various activities. In other words, we can say that various activities put together are referred to as the system development life cycle.

In the System Analysis and Design terminology, the system development life cycle also means software development life cycle.

Following are the different phases of system development life cycle: l Preliminary study l Feasibility study l Detailed system study l System analysis l System design l Coding l Testing l Implementation l Maintenance (a) Preliminary System Study is the first stage of system development life cycle.

This is a brief investigation of the system under consideration and gives a clear picture of what actually the physical system is.

In practice, the initial system study involves the preparation of a ‘System Proposal’ which lists the Problem Definition, Objectives of the Study, Terms of reference for Study, Constraints, Expected benefits of the new system, etc. in the light of the user requirements.

The system proposal is prepared by the System Analyst (who studies the system) and places it before the user management.

The management may accept the proposal and the cycle proceeds to the next stage. The management may also reject the proposal or request some modifications in the proposal.

In summary, we would say that the system study phase passes through the following steps: l problem identification and project initiation l background analysis l inference or findings (system proposal)

(b) Feasibility Study In case the system proposal is acceptable to the management, the next phase is to examine the feasibility of the system.

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, cost-effectiveness.

These are categorized as technical, operational, economic, and schedule feasibility. The main goal of the feasibility study is not to solve the problem but to achieve the scope.

In the process of the feasibility study, the cost and benefits are estimated with greater accuracy to find the Return on Investment (ROI).

This also defines the resources needed to complete the detailed investigation. The result is a feasibility report submitted to the management. This may be accepted or accepted with modifications or rejected.

The system cycle proceeds only if the management accepts it. (c) Detailed System Study The detailed investigation of the system is carried out in accordance with the objectives of the proposed system.

This involves a detailed study of various operations performed by a system and their relationships within and outside the system.

During this process, data are collected on the available files, decision points, and transactions handled by the present system.

Interviews, on-site observation, and questionnaires are the tools used for detailed system study.

Using the following steps it becomes easy to draw the exact boundary of the new system under consideration: l Keeping in view the problems and new requirements l Workout the pros and cons including new areas of the system All the data and the findings must be documented in the form of detailed data flow diagrams (DFDs), data dictionary, logical data structures, and miniature specification.

The main points to be discussed in this stage are l Specifications of what the new system is to accomplish based on the user requirements.

l Functional hierarchy showing the functions to be performed by the new system and their relationship with each other.

l Functional networks are similar to function hierarchy but they highlight the functions which are common to more than one procedure.

l List of attributes of the entities – these are the data items that need to be held about each entity (a record)

Author
Language English
No. of Pages10
PDF Size0.1 MB
CategoryEngineering
Source/Creditsnios.ac.in

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