Waterfall SDLC model

Waterfall SDLC model - a predictive approach

The VCE IT model of the System Development Life Cycle (SDLC) contains 5 stages that flow from one to the next in order (hence the 'waterfall' imagery.) As with a real waterfall, the progression from stage to stage is one-way only, and a stage, once completed, is not revisited.

An advantage of the water It is popular because each stage can be compartmentalised (so one stage is completely separate to other stages and there is no overlapping) and the project's deadlines can be set, monitored and managed tidily.

A disadvantage of the Waterfall model is that it is so linear and sequential. Once a phase begins, if a team discovers a previous stage they had not thought out properly or a vastly better method were possible, the team would have to persevere with the existing plan: they cannot revisit the analysis phase, for example, to do more observation and better understand the nature of the problem.

There are alternatives to the strictness of the Waterfall model: you will need to be familiar with Rapid Application Development (RAD), but other models include Joint Application Development (JAD), Synch and Stabilise, Build and Fix, and the Spiral Model of the SDLC.

The Waterfall SDLC steps are:

• Analyse - study the current system; determine if there is really a problem; determine if the problem can be fixed; determine if the problem is worth fixing; determine what the new or changed system should be able to achieve. Finish with a logical design. Details.
• Design - Consider alternative ways of solving the problem; plan what hardware, software, procedures and data need to be created, purchased or assembled. Design other key features such as documentation, training, testing, implementation and evaluation requirements. Finish with a physical design.
• Develop - write the software, build the hardware, buy equipment, assemble components, formalise procedures of how the product should be used, perform ongoing informal component testing and integration testing. Write the documentation and training procedures. Finish with format testing, including acceptance testing.
• Implement - roll out the solution to its users using strategies such as direct, phased, parallel and/or pilot.
• Evaluate - review the development process and the finished product to learn from mistakes and identify good practices. Ensure the finished product is performing as specified during the design phase.