System Development Life Cycle (SDLC) | SAD


Developing Information Systems and System Development Life Cycle (SDLC)

Most organizations use a standard set of steps, called a systems development methodology to develop and support their information systems. It is a standard process followed in an organization to conduct all the steps necessary to analyze, design, implement, and maintain information systems. And systems development life cycle (SDLC) is the traditional methodology used to develop, maintain, and replace information systems. It includes different phases as shown in the figure below. This representation of SDLC is sometimes referred to as the waterfall model or classic life cycle.
 
Developing Information Systems and System Development Life Cycle (SDLC)
Fig: The systems development life cycle

The first phase is called planning. In this phase, someone identifies the need for a new or enhanced system. These needs are then analyzed, prioritized and arranged into a plan for the IS department. Here, a potential information systems project is explained and an argument for continuing or not continuing with the project is presented; a detailed plan is also developed for conducting the remaining phases or the SDLC for the proposed system.
The next phase is called analysis. During this phase, the analyst studies the current system and proposes alternative replacement systems. Here, the analyst thoroughly studies the organization’s current procedures and the information systems used to perform organizational tasks. The analyst work with users to determine what the users want from a proposed system. The analyst carefully studies any current systems, manual and computerized, that might be replaced or enhanced as part of this project. The analyst studies the requirements and structures them according to their interrelationships and eliminates any redundancies; generates alternative initial designs to match the requirements; compare these alternatives to determine which best meets the requirements within the cost, labor, and technical levels the organization is willing to commit to the development process. The output of this phase is a description of the recommended alternative solution. Once the recommendation is accepted by owners, you can begin to make plans to acquire any hardware and system software necessary to build or operate the system as proposed.
The next phase is called design. During this phase, you convert the description of the recommended alternative solution into logical and then physical system specification. Here, you must design all aspects of the system form input and output screens to reports, databases, and computer processes. Logical design is the part of the design process that is independent of any specific hardware or software platform. Theoretically, the system could be implemented on any hardware and systems software. Physical design is the part of the design phase in which the logical specifications of the system from logical design are transformed into technology-specific details from which all programming and system construction can be accomplished.
The next phase is called implementation. In this phase, the information system is coded, tested, installed, and supported in the organization. During coding, programmers write the programs that make up the information system. During testing, programmers and analysts test individual programs and the entire system in order to find and correct errors. During installation, the new system becomes a part of the daily activities of the organization. Implementation activities also include initial user support such as the finalization of documentation, training programs, and ongoing user assistance.
The final phase of SDLC is called maintenance. In this phase, information system is systematically repaired and improved. When a system is operating in an organization, users sometimes find problems with how it works and often think of better ways to perform its functions. Also the organization’s needs with respect to the system change over time. In maintenance, you make the changes that users ask for and modify the system to reflect changing business conditions. Waterfall model is the oldest and the most widely used paradigm for information systems development. While it does have weaknesses, it is significantly better than a haphazard approach. This model is suitable for the projects in which user requirements are certain and precise. The problems that are sometimes encountered with the linear sequential model are:
Changes can cause confusion as the project team proceeds.
It is often difficult for the customer to state all requirements explicitly. The linear sequential model requires this and makes difficulty to respond to changing customer requirements.
A working version of the system will be available to customers late in the project time-span. A major blunder, if undetected until the working program is reviewed, can be disastrous.
The linear nature of the classic life cycle leads to “blocking states” in which some project team members must wait for other members of the team to complete dependent tasks.
User involvement is limited.

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