Agile development has little in common with the waterfall model. As of 2009, the waterfall model is still in common use. The waterfall model is the most structured of the methods, stepping through requirements-capture, analysis, design, coding, and testing in a strict, pre-planned sequence.Progress is generally measured in terms of deliverable artifacts: Requirement specifications, Design documents, Test plans, Code reviews and the like.
The main problem with the waterfall model is the inflexible division of a project into separate stages, so that commitments are made early on, and it is difficult to react to changes in requirements. Iterations are expensive. This means that the waterfall model is likely to be unsuitable if requirements are not well understood or are likely to change in the course of the project.
Agile methods, in contrast, produce completely developed and tested features (but a very small subset of the whole) every few weeks. The emphasis is on obtaining the smallest workable piece of functionality to deliver business value early, and continually improving it/adding further functionality throughout the life of the project.
In this respect, agile critics may assert that these features are not placed in context of the overall project, concluding that, if the sponsors of the project are concerned about completing certain goals with a defined timeline or budget, agile may not be appropriate. Proponents of Agile development counter that adaptations of Scrum show how agile methods are augmented to produce and continuously improve a strategic plan.
Some agile teams use the waterfall model on a small scale, repeating the entire waterfall cycle in every iteration. Other teams, most notably Extreme Programming teams, work on activities simultaneously. |
Although the Waterfall (SDLC, or Plan-Based) development model has been with us for many years, Agile Development has made headlines lately due to many successful development groups improving their capabilities to deliver software projects on-time and on-budget using the Agile Development Model. Many groups that are poised to adopt a development methodology want to know just what the Agile Development Model is and how it is different from the traditional Waterfall method.
Waterfall projects are best suited for life-critical applications, government bid-type contracts, offshore-developed projects, and large enterprise-size development projects where time-estimation, external-system impacts, and progress-tracking are important. Waterfall projects also cater well to quality systems like CMMI and ISO.
Borrowing from Agile, Waterfall projects can be enhanced with daily standup-meetings, sprint-meetings, and periodic user-reviews to improve the communication process.
Projects that don't require a quality system, aggressive up-front estimation, or life-critical planning fit well with the Agile Development Model. Internal tools, non-enterprise products, and development shops that are not calendar-driven find Agile a good fit.
In reality, a good software development department would know how to do both models, and would implement each were necessary. |
