Waterfall Model

The Waterfall Model was the first Process Model to be introduced. It is very simple to understand and use.

Requirements

´  The first phase involves understanding what needs to design and what is its function, purpose, etc.

System Design

´   System Design helps in specifying hardware and system requirements and also helps in defining overall system architecture.

Implementation

´  With inputs from system design, the system is first developed in small programs called units, which are integrated into 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,

´   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.

´   The client is provided with regular maintenance and support for the developed software.

 Advantages of the Waterfall Model

´  Simple and easy to understand and use.

´  Easy to manage

´  Phases are processed and complete one at a time.

´  Requirement are very well understanding.

´  Clearly defined stages.

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.

´  No working software is produced until late during the life cycle.

´  High amount of risk.

´  Not good for OOP.