The waterfall model is a sequential software development process (a process for the creation of software) in which development is seen as flowing steadily downwards (like a waterfall) through the phases of requirements analysis, design, implementation, testing (validation), integration, and maintenance.
Welcome to CWAnswers
CWAnswers is your guide to the sprawling world wide web. The directory aims to provide a useful guide made by users. You can share your knowledge as well - simply sign up and edit your first entry. For questions just contact the team at support - at - cwanswers.com.
Weblinks for Waterfall Model
Top 10 for Waterfall Model
Things about Waterfall Model you find nowhere else.
Select content modules
The waterfall model is a sequential software development process (a process for the creation of software) in which development is seen as flowing steadily downwards (like a waterfall) through the phases of requirements analysis, design, implementation, testing (validation), integration, and maintenance.
Model
- Requirements specification
- Design
- Construction (AKA implementation or coding)
- Integration
- Testing and debugging (AKA Validation)
- Installation
- Maintenance
To follow the waterfall model, one proceeds from one phase to the next in a purely sequential manner. For example, one first completes requirements specification, which are set in stone. When the requirements are fully completed, one proceeds to design. The software in question is designed and a blueprint is drawn for implementers (coders) to follow — this design should be a plan for implementing the requirements given. When the design is fully completed, an implementation of that design is made by coders. Towards the later stages of this implementation phase, disparate software components produced are combined to introduce new functionality and remove bugs.
Thus the waterfall model maintains that one should move to a phase only when its preceding phase is completed and perfected. However, there are various modified waterfall models (including Royce's final model) that may include slight or major variations upon this process.
Usage
The waterfall model is widely used by such large software development houses as those employed by the U.S. Department of Defense and NASA, and for many large government projects (see "the standard waterfall model" on the Internet Archive). Those who use such methods do not always formally distinguish between the pure waterfall model and the various modified waterfall models, so it can be difficult to discern exactly which models are being used and to what extent.
The U.S. Department of Defense has moved away from the waterfall model since 1994 with MIL-STD-498 and in 1998 with IEEE 12207.
Supporting arguments
Time spent early on in software production can lead to greater economy later on in the software lifecycle; that is, it has been shown many times that a bug found in the early stages of the production lifecycle (such as requirements specification or design) is cheaper, in terms of money, effort and time, to fix than the same bug found later on in the process. (1996, p. 72, estimates that "a requirements defect that is left undetected until construction or maintenance will cost 50 to 200 times as much to fix as it would have cost to fix at requirements time.") To take an extreme example, if a program design turns out to be impossible to implement, it is easier to fix the design at the design stage than to realize months later, when program components are being integrated, that all the work done so far has to be scrapped because of a broken design. the proponent is Lei Marie Carbonel
