SYSTEM DEVELOPMENT LIFE CYCLE (SDLC) (TRADITIONAL MODEL)
This methodology was first developed in the 1960s to manage the large software projects associated with corporate systems running on mainframes. It is a very structured and risk-averse methodology designed to manage large projects that included multiple programmers and systems that would have a large impact on the organization.
SDLC is defined as the process (as a whole) of development system or software to meet certain requirements. It covers many activities; starts from understanding why the system should be built studying the project visibility, analyzing problems, choosing the system and architecture, implementing and testing it, up to deliver 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: –
1. Problem definition
2. Feasibility study
3. System Analysis
4. System Development / construction/ codding/ Programming
7. Maintenance and Review
The first stage of any project, sometimes called the preliminary assessment, is a brief investigation of the system under consideration to provide to any project team. The idea of developing a new system occurs to the user when he recognizes that he has a problem with the means by which he currently carries out his business. This awareness marks the beginning of the recognition of problem phase, as almost all computer systems replace an existing system.
It identifies the problem to be solved and how it fits with the current business and technology in line with the original goals and objectives. This will be when the organization realizes that it cannot cope with certain business needs because the existing system (manual or computerized) is failing and is not satisfactory or there is a lag in model developments. A steering committee is formed which look into project and works with personal from the affected department.
Its outcomes are a detailed terms of reference document which define the problem, states the objectives, details the scope of investigation i.e. boundaries of project, lists the resources required and available, states the time frame of the project, explain system limitations and constraints. A system analyst’s first task is to obtain more crucial information by interviewing and meeting concerned people. This will clarify how the problem was felt, how often it occurs, how it affects the business and which departments are suffering with this. Analyst does not do detailed investigation at this stage but he tries to define the scope of the problem; classifies it and measures its complexity to ensure that the problem is important and real enough to require further investigation. A proper understanding of the problem and its classification enables the systems analyst to separate symptoms from the real causes. It also helps the analyst to consider it as a systems problem rather than a business problem and thereby increasing the chances of success in proposing solutions.
Following is the major classification of the problems:
• The existing system is slow and cannot respond to information i.e. problem of responsiveness. In this case the analyst will look to (i) find out present level of responsiveness and factors contributing to it and; (ii) consider what changes or additions in existing procedures or resources; utilization would improve responsiveness and how such changes affect the organization.
• Originating workload is higher than the volume of workload handled i.e. problem of throughput. Here the analyst concentrates on finding the level of productiveness, its contributing factors, which further facilitates to improve productivity by better utilization of resources of by modifications to methods & resources.
• The present services are very expensive e. problem of economy. The management intentions could be (i) to reduce cost for same productivity (ii) to increase productivity but at present cost level of (iii) discontinue unproductive operations.
• Problem of Occurrence/ Reliability: At first, the analyst checks operations, step by step, to see when and how errors creep up & how to restrict these errors by using various clarification checks. For reliability, the system may have to be designed without any ambiguity and must be foolproof, as system failures result in loss of business.
• There is a problem of information, where the analyst would be concerned with organization of available information, its accessibility for decision making. These types of problems have close relationship with the ways of data storage and organization.
• Problem of efficiency. This problem is interrelated to all the above problems. The analyst must create a proper balance between all the contributing factors like response time, workload volume, cost of processing, and information needs etc.
• Problem of security of information: Here the analyst tries to devise controls over accessibility of information
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. It is a research into the possibility of developing a solution to a problem. The study is to justify the change in the current system.
The following steps are used in the complete feasibility study:
i. Study the existing system
ii. Define the scope of the proposed system
iii. Study the strengths and weakness of the existing system
iv. Study various alternatives
v. Carry out feasibility studies
vi. Get the management approvals
These are categorized as technical, operational, economic, schedule and social feasibility. 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 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. In short, following decision are taken in different feasibility study:
Types of Feasibility study
1. Technical feasibility – Whether the problem is to be solved using existing technology and resources available? I.e. It tries to see whether the existing technology will support a new system to be developed using the organization current computing facilities. If the current facilities are not adequate, the organization is force to acquire the necessary hardware and software technologies available in the market.
2. Economic feasibility – The likely benefits outweigh the cost of solving the problem which is generally demonstrated by a cost/ benefit analysis.ie It determines if the benefits to be derived from the system recommendation are worth the time and other resources that are required to achieve the recommended system.
3. Operational feasibility – Whether the problem can be solved in the user’s environment with existing and proposed system workings? It is a determination that the system will be able to perform the designated functions within the existing procedures. If end users resist a new system, it might not be used to it full potential. It also looks at the human resource implications of implementing the system such as retrenchment. Etc.