Chapter 2: System Development Life Cycle modelsSession 3
Recap•Last Session–Introduction on System Concepts, types–Introduction to System analysis and design•Todays focus–Different kinds of System development methodologies.
Need•Years ago operations in organizations were limited.–Possible to utilise manual procedures•Growth over the years-need to automate procedures i.e–Maintaining record of 1000 employees on paper.
Cont’•As Organizations opted for automation,–Need for standard and structural procedure/methodology to be introduced to make transition from manual to automated system easy•System Development Lifecycle was born•Waterfall model first model•Others later–Prototyping–Rapid Application Development etc.
A methodology•is a formalized approach to implementing the SDLC (i.e., it is a list of steps and deliverables).
System Development•begins with –the recognition of user needs. –Then there is a preliminary investigation stage.•It includes evaluation of present system, information gathering, feasibility study, and request approval.–Feasibility study includes technical, economic, legal and operational feasibility. In economic feasibility cost-benefit analysis is done. –After that, there are detailed design,–implementation, –testing and–maintenance stages
System Development Stages
Activities involved in any Life cycle Model1. Preliminary Investigation2. Determination of System's requirements: Analysis phase3. Design of System4. Development of Software5. System Testing6. Implementation and Maintenance
Preliminary Investigation•It initiates with a project request. •First stage is the preliminary analysis. –Aim is to identify the problem. First, need for the new or the enhanced system is established. •Only after the recognition of need, for the proposed system is done then further analysis is possible.
Case Study-Leave Management•A company whose leave-applications are processed manually. Now this company is recruiting many new people every year. •The number of employee in the company has increased. So manual processing of leave application is becoming very difficult. •So the management is considering the option of automating the leave processing system. •If this is the case, then the system analyst would need to–investigate the existing system, find the limitations present, and finally evaluate whether automating the system would help the organization
Cont’•After completion of initial investigation and the need for new or improved system is established, •All possible alternate solutions are chalked out- "candidate systems". –Are weighed and the best alternative of all these is selected as the solution system, "proposed system".