The System Development Life Cycle:

System Development Life Cycle (SDLC) Methodologies

SDLC (System Development Life Cycle), just as the name implies, is defined as the process (as a whole) of developing system or software to meet certain requirements. It covers many activities; starts from understanding why the system should be built, studying the project feasibility, analyzing problems, choosing the system design and architecture, implementing and testing it, up to delivering the system as product to the user. SDLC is a process of gradual refinement, meaning that it is done through several development phases. Each phase continues and refines what’s done in the previous phase. Commonly known development phases in SDLC are:

• Planning. It is the process of understanding why the system should be built and defining its requirements. It also includes feasibility study from several different perspectives, technical, economic, and organization feasibility aspects.
• Analysis. This phase includes activities such as problems identifying and analysis, and even predicting potential problems that may arise in the future regarding the system. The deliverables / products of this phase will drive how the system will be built and guide the developers’ works.
• Design. System analysis leads to design decision, which exactly determines how the system operates in terms of process, data, hardware, network infrastructures, user interface, and other important factors in the system environment.
• Implementation. This is probably the most resource-, cost-, and time-consuming phase of all. This is when the system is actually built, tested, and finally installed. It also includes activities such as user training and system maintenance. Some experts like to separate them into different phases Deployment and Maintenance. However the four phases are the most commonly known and accepted steps.

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 with in the organization – top management, the user, the analyst. User-originated ideas also prompt initial investigation.

Impetus for System Change

The ideas for change originate in the environment or from within the firm Environment-based ideas originate from customers, vendors, government sources, and the like. For example, new unemployment compensation regulations may make it necessary to change the restructures. Customer complaints about the delivery of orders may prompt an investigation of the delivery schedule, the experience of truck drivers, or the volume of orders to be delivered. When investigated, each of these ideas may lead to a problem definition as a first step in the system life cycle process.

Feasibility Study

Depending on the results of the initial investigation, the survey is expanded to a more detailed feasibility study. As we shall learn, 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. It focuses on there major questions:

• What are the user’s demonstrable needs and how does a candidate system meet them?
• What resources are available for given candidate systems? Is the problem worth solving?
• What are the likely impact of the candidate system on the organization? How will it fit within the organization’s master MIS plan?

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.

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.

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.