Waterfall Model

As I was in the university, I used to learn lot about Waterfall model of software development life cycle. It was such as uncomplicated process to learn. But after been in the software development industry for more than four year, I'm been convinced that Waterfall model software development process is not going to valid for more projects popping up these dates.

Summery if the phases of Waterfall model

1. Requirements – Gathering, analyzing, documenting and etc.
   
2. Design – design system for functional and non functional requirements
   
3. Development – It's all about coding and developer testing
   
4. Testing And Verification – the testing conducted by the dedicated testing team in the organization after a particular release of the system is delivered. There can be number of releases is been delivered in this phase and testing team is reporting for the bugs system is consist of and developer team is fixing them to deliver the well behaved features with the very next release.
   
5. Finally, it deployment and maintenance.
   

Success Stories of Waterfall model

If I'm talking about my experience, there were projects which were developing smoothly at least for more than six months without interruptions to change the requirement in the mean time development in progress.

The first large scale project which I was working on is a migration. It was to already implemented Time Management system (But it was large number of feature that just not a time management, had more than 8 modules each averagely estimated to 2000 hours) and it was implemented using C++ and VB. Customer was facing barrier of providing more and more feature with the existing one.

The requirement was cleared, well identified already, and what all we need to start doing things from Use cases to Deployment, Client was not so annoyed to change the requirements and he got what he was looking for at the end of the project.

This is an example of one of the success story of the Waterfall model, but it was also not a 100% success story.

But more than 95% of projects currently in progress of development would be failed with Waterfall Model.

Why Waterfall model is not success in most cases.

1. Difficult to responds for the requirements changes are raised to by the customer after starting development and designs.
   
2. Difficult to respond new requirements are requested by customer after starting of the development and designs.
   
3. Cycle is draw out for long period of time which customer has to wait to see check whether that developer has delivered the system what they were looking for.
   
4. Business rules are changing rapidly in today businesses, waterfall model is not good enough to address it.
5. etc.
   

Regards

Lakmal