Waterfall Model

Waterfall model

Definition :-

            The waterfall model is a relatively linear sequential design approach for certain areas of engineering design. In software development, it tends to be among the less iterative and flexible approaches, as progress flows in largely one direction ("downwards" like a waterfall) through the phases of conception, initiation, analysis, design, construction, testing, deployment and maintenance.

            
            The waterfall development model originated in the manufacturing and construction industries; where the highly structured physical environments meant that design changes became prohibitively expensive much sooner in the development process. When first adopted for software development, there were no recognized alternatives for knowledge-based creative work.

Sequential Phases in Waterfall Model

Requirements

            The first phase involves understanding what need to be design and what is its function, purpose etc. Here, the specifications of the input and output or the final product are studied and marked.

System Design

            The requirement specifications from first phase are studied in this phase and system design is prepared. System Design helps in specifying hardware and system requirements and also helps in defining overall system architecture. The software code to be written in the next stage is created now.

Implementation

            With inputs from system design, the system is first developed in small programs called units, which are integrated in the next phase. Each unit is developed and tested for its functionality which is referred to as Unit Testing.

Integration and Testing

            All the units developed in the implementation phase are integrated into a system after testing of each unit. The software designed, needs to go through constant software testing to find out if there are any flaw or errors. Testing is done so that the client does not face any problem during the installation of the software.

Deployment of System

            Once the functional and non-functional testing is done, the product is deployed in the customer environment or released into the market.

Maintenance

            This step occurs after installation, and involves making modifications to the system or an individual component to alter attributes or improve performance.These modifications arise either due to change requests initiated by the customer, or defects uncovered during live use of the system. Client is provided with regular maintenance and support for the developed software.

Advantages of Waterfall Model

·         The advantage of waterfall development is that it allows for departmentalization and control. A schedule can be set with deadlines for each stage of development and a product can proceed through the development process model phases one by one. 

·         The waterfall model progresses through easily understandable and explainable phases and thus it is easy to use. 

·         It is easy to manage due to the rigidity of the model – each phase has specific deliverables and a review process.

·         In this model, phases are processed and completed one at a time and they do not overlap. Waterfall model works well for smaller projects where requirements are very well understood.

Disadvantages of Waterfall Model

·         It is difficult to estimate time and cost for each phase of the development process. 

·         Once an application is in the testing stage, it is very difficult to go back and change something   that was not well-thought out in the concept stage. 

·         Not a good model for complex and object-oriented projects. 

·         Not suitable for the projects where requirements are at a moderate to high risk of changing.