The Waterfall and Agile models for software development project management each offer advantages and disadvantages, and the best model for a given project depends on project goals, client priorities, and the strengths of the project manager and team.
The differences in the models' structures lead to some significant differences in the way the projects run and the kind of final products they produce.
|Agile Vs Waterfall|
- The Waterfall model lays out a rigid plan for the project, beginning with conception and moving through design, construction, testing, and deployment.
- Int the Waterfall model requirements for the final product are clearly and inflexibly set during the conception phase, and each successive phase of the project must be completed before work can begin on the next phase.
- The Agile model moves through a series of iterations of the product, with testing and client approval being a part of each iteration.
- At the conclusion of each iteration, project goals are reassessed, and new goals are incorporated into the next iteration of the agile project.
- The Agile project management model is, by design, more flexible than the Waterfall model.
- Agile project goals can be adjusted during each iteration, and the project can more easily adapt to unforeseen challenges and opportunities.
- Waterfall projects do not allow for goal adjustments during the process, and unexpected obstacles can threaten the success of the entire project.
- Agile and Waterfall projects differ considerably in the extent and timing of client involvement.
- In general, Agile projects require much more client involvement throughout the project than do Waterfall projects.
- With Waterfall project management, the client is involved during the conception stage of the project but need not be involved again until the deployment phase.
- In an Agile project, the client is involved throughout the process. This gives the client a measure of control through the entire process, but it also gives rise to the potential for unexpected revisions of the project plan, which can lead to schedule overruns and new obstacles.
- Agile project teams are typically small, and team members are often versatile in their skill sets.
- Team members are also typically involved with the project throughout its duration. Waterfall project team members may only be involved with the project during the distinct phase for which they are responsible, allowing them to work on other projects when their involvement is not required.
Speed of Deployment
- Because Agile projects are tested and approved at each iteration, there's the possibility that an acceptable version of the product could be deployed relatively early in the process.
- Waterfall projects are deployed only at the end of the process, and there is no room for schedule flexibility.
- The Waterfall model creates an extremely well-defined project process, with a beginning, middle and end, as well as a clearly marked path for getting from one end to the other and a clearly delineated picture of what the final product will look like.
- An Agile project, because it may be developed in discreet stages, has a tendency to be less coherent.
- As the project moves through successive iterations, project goals may change, and the final product may end up looking substantially different from the initial conception.
- While often an advantage of the model, this lack of a clear pathway also brings the danger of schedule overruns and discreet project components that do not work well together.
The two models lie at either end of a spectrum with predictability at one end and flexibility at the other. The correct model to choose for a given project depends on where on the spectrum the project's priorities fall.