System Development Life Cycle:   -   A System development life cycle is a framework consisting of many stages. Each stage has its own key questions and importance. Either we can improve the existing system or create new system. We have to perform all the stages step by step. System analysis and design are the key stages of system life cycle. In system engineering, information system and software engineering, is the process of creating or altering the system, and it contains models and methodologies that analyst use to develop these systems.

Systems Development Life Cycle (SDLC) is a process used by which asystems analyst can develop an information system, includingrequirements, validation, training, and user (stakeholder) ownership. Inproject management, a project can be defined both with a project life cycle (PLC) and an SDLC. According to Taylor (2004) "the project life cycle encompasses all the activities of the project, while the systems development life cycle focuses on realizing the product requirements".

It is also called system study. The system analyst gives a system development project meaning and direction with the help of SDLC.

The stages of system development life cycle are given below: -1.      Recognition of Needs.2.      Feasibility Study.3.      Analysis.4.      Design.5.      Implementation.6.      Post-Implementation and Maintenance.

Recognition of Needs

One must know what the problem is before it can be solved. The basis of candidate system is recognition of need for improving the system. The key question is:

What is the problem?

This recognition of need leads to a preliminary survey or an initial investigation of current system to determine whether an alternative system can solve the problem. If the problem is serious enough, management may have an analyst look at it.

The idea for change may originate in the environment or within the firm. Environment-based ideas originate from customers, vendors, government sources etc. When investigated each of these ideas may lead to a problem definition. Idea for change may also come from within the organization – top management, the user, the analyst. User-originated ideas also prompt initial investigation.

Feasibility Study

Depending upon the results of the initial investigation, the survey is expanded to a more detailed feasibility study. A feasibility study is a test of a system proposal according to its workability, impact on the organization, ability to meet user needs and effective use of resources. The key questions are:-

 1.    What are the user’s demonstrable needs and how does a candidate system meet them?

2.      What resources are available for given candidate systems? Is the problem worth solving?

3.      What is the impact of the candidate system on the organization? How well does it is fit within the organization’s master Master Information System plan?

Each of these questions must be answered carefully. All of these questions help to investigate and to evaluate the problem, the cost of each system and final selection of the best system.

The objective of a feasibility study is not to solve the problem but to acquire a sense of its scope. Consequently, Cost and benefits are estimated with greater accuracy at this stage.The result of the feasibility study is a formal proposal. This is simply a formal document detailing the nature and scope of the proposed solution.

Analysis

Analysis is a detailed study of the various operations performed by a system and their relationships with in and outside of the system. A key question is: -

What must be done to solve the problem?

During analysis, data are collected from the available files, decision points and transactions handled by the current system. Tools that are used in analysis are data flow diagrams, interviews, on-site observation, and questionnaires. The interview is a commonly used tool in analysis. Training, experience and common sense are required for collection of the information needed to do the analysis. Once the analysis is completed, the analyst understands that what is to be done?

Design

The tern design describes the final system and the process by which it is developed. It also refers to the technical blue print that will be applied in implementing the candidate system. It also includes the construction of programs and program testing. The key question is: -

How should the problem solved?

The first step in designing is to determine How the output is to be produced and in what format?

The second step is input data and master files (database) have to be designed to meet the requirements of the proposed output.

The third step includes a list of programs needed to meet the system’s objectives and complete documentation.

Finally, Details related to justification of the system and the impact of the candidate system on the user and the organization. These details are documented and evaluated by management.

Before the implementation phase, the final reports like procedural flowcharts, records layouts, report layouts and a workable plan are prepared for implementing the candidate system. At this point, projected costs must be close to actual costs of implementation.

Implementation

The implementation phase is directly concerned with user training, site preparation and file conversion. During the final testing, user acceptance testing is followed by the user training. Conversion usually takes place at about the same time when the user is being trained. Once the program become available and data are ready for testing and the results are OK then the program is run with “live†� data. Otherwise, a diagnostic procedure is used to locate and correct errors in the program.

Sometime, a parallel run is conducted where the new system runs simultaneously with the “old†� system. This method may be costly but provides added assurance against errors in the candidate system. In some cases, parallel processing is not practical possible like it is not possible to run parallel two online point-of-sale (POS) systems for retail chain.

Post-Implementation and Maintenance

After the installation phase is completed and the user or staff is adjusted to the changes create by the candidate system. Evaluation and Maintenance begins. If the new information is inconsistent with the design specifications then changes have to be made. Hardware’s also require periodic maintenance to keep in tune with design specifications.

Changes in organizations requirements or environmental factors also call for system enhancements. This change requires evaluation, program modifications and further testing.

At last, a system project may be dropped at any time prior to Implementation. So, it is the responsibility of the analyst to collect proper information or perform accurately every phase.