Waterfall model

1970 Royce Managing the Development of Large Software Systems Fig10

Waterfall Model is a sequential (non-iterative) design process, used in software development processes, in which progress is seen as flowing steadily downwards (like a waterfall) through the phases of Conception, Initiation, Analysis, Design, Construction, Testing, Production/Implementation, and Maintenance. This model is one of the earliest approaches to software development and is a subset of the Systems Development Life Cycle (SDLC).

Overview

The Waterfall model is a linear and sequential approach where each phase must be completed before the next phase can begin. There is no overlapping or iterative steps. The outcome of one phase acts as the input for the next phase sequentially. This model is best suited for projects where requirements are well-understood and changes will be minimal during the development process.

Phases

The Waterfall model is divided into several discrete phases:

1. Conception: The project's goals, scope, and constraints are defined.
2. Initiation: Resources are allocated, and teams are formed.
3. Analysis: Requirements are gathered, and analyzed to create a detailed specification of the software.
4. Design: The software's architecture and design are planned.
5. Construction: Actual coding and development of the software take place.
6. Testing: The software is rigorously tested to find and fix bugs.
7. Production/Implementation: The software is deployed to the user environment.
8. Maintenance: Ongoing support is provided, and the software is updated as needed.

Advantages

• Simplicity and ease of use: The Waterfall model is straightforward to understand and use.
• Structured approach: Each phase has specific deliverables and a review process.
• Early identification of issues: As each phase has defined goals and outcomes, issues can be identified early in the development process.

Disadvantages

• Inflexibility: Once a phase is completed, it is difficult to go back and make changes.
• Assumes requirements are well-understood: The model is not well suited for projects where requirements are likely to change.
• Delayed testing: Since testing only occurs after the build phase, it can lead to the discovery of issues late in the process.

Applications

The Waterfall model is best applied to projects where requirements are clear from the beginning and unlikely to change. It is often used in large systems engineering projects where a system is developed at a large scale.

See also

• Agile Software Development
• V-Model
• Iterative and Incremental Development
• Software Development Process