Unit 201 Models of Software Development Life Cycle (SDLC) The objective of this section is to introduce you the idea of software process – a coherent set of activities for software production. When you have read this section you will: understand the concept of a software process and a software process model; understand a number of different software process models such as waterfall, spiral and iterative models.

Unit 202 An SDLC model breaks down the development process into a sequence of phases or stages. The end of a phase is called a milestone of the project. The outcome of the phase is delivered to the customer as a milestone of the project. Breaking down the development process makes it easier to manage. Each phase can be performed in various ways. What is a SDLC Model?

Unit 203 In the earlier days, projects were developed without proper specification or any attempt in design and were just built, and reworked as many times needed to satisfy the customer. This is not possible for complex projects since There is no control on quality assurance. There is no risk analysis. There is no estimation of time and cost of the project. There is no proper plan. Hence, The project may lead to a huge financial loss for both the customer as well as the developer. The project may fail. The project may not be delivered in time with the satisfaction of the customer. Why use SDLC Model?

Unit Waterfall Model In the waterfall model, software activities proceed logically through a sequence of steps. Each step bases its work on the activities of the previous step. The design phase logically follows the requirements phase, the implementation phase follows the design phase, and so on. Waterfall model is document driven. In principle, the result of each phase is one or more documents which are approved (“sign-off”). The next phase should not start until the current phase is completed.

Unit 205 Workflow of Waterfall Model Requirement Verify Implementation Testing Planning Verify Retirement Design Verify Integration Testing Deployment and Maintenance Specification Verify Development Maintenance Changed Requirements verify

Unit 206 Quiz 1.The planning of the project is done by: A.The programmer B.The system analyst C.The system study team D.The project manager 2.During the Specification mode, the requirements are properly documented and the document is called _________. 3.The waterfall model is 1.Document-driven. 2.Risk-driven 3.Prototype-driven