1.Waterfall Model * The waterfall model is also called the classic life cycle * The waterfall model is used when the requirements are well understood and unlikely to change during the system development. * This process begins with customer specification of requirements and progress through different activities like planning, modeling, construction and deployment and ends in complete software product. * In waterfall model,each phase must be completed fully before the next phase can begin.At the end of each phase,a review takes place to determine if the project is on the right path or not. * In waterfall model,phases do not overlap. * It is also known as oldest paradigm for software engineering. * Waterfall model is an example of plan-driven process,i.e,plan and schedule all the process activities before starting work on them. * Stages of waterfall model:
Requirement analysis: The system services, constraints and goals are established by consultation with system users.They are defined in detail and serve as system specification.
System and software design:The system design process allocates the requirements to either hardware or software systems by establishing an overall system architecture.
Implementation : During this stage, the software design is relized as a set of programs or program units .Unit testing involves verification.
Integration and system testing : The individual program units or program are tested as a complete system to ensure that the software requirements have been met.After testing,software system is delivered to customer.
Maintenance: Maintenance involves correcting errors which were not discovered in early stage of lifecycle.
* Merits of waterfall model: 1. Works well for smaller projects where requirements are vry well understood. 2. Phases are processed and completed one at a time. 3. Easy to manage due to