Agile Vs Waterfall Methodology

How Exactly Both of Them Work

Waterfall provides a more sequential approach to software development. It works in the following order.

• Software requirement document is gathered
• The application is designed after requirement is finalized
• Development begins and parallelly unit testing is executed
• Performance testing is carried out to ensure the system performs well under load or stress
• User acceptance testing confirms the build against the agreed requirements
• Defect fixing where the developer starts working on the bugs detected by the testing team
• The application is deployed in production

Agile, however, does not follow a linear path. It follows an iterative approach in which the duration of the project is divided into short cycles called sprints. Its priorities come from the four values of the Manifesto for Agile Software Development, published in 2001:

• Individuals and interactions over processes and tools.
• Working software over comprehensive documentation.
• Customer collaboration over contract negotiation.
• Responding to change over following a plan.

The manifesto adds that the items on the right still have value, and that agile teams value the items on the left more.

Requirement Gathering Phase

If the waterfall model is used for application development, both the customer and the organization need a clear understanding of the requirement specifications beforehand. There is no scope for changing them once the requirements are accepted.

In agile, however, there is no fixed requirement document at the start. The customer provides user stories in each sprint, and the developers finish the code and present a demo. If the customer wants changes or more features, they request them for a later sprint. Agile is therefore more flexible about requirements than waterfall.

Suitable Projects

If the customer is clear about the requirements of the software that is going to be developed, the waterfall model is the best approach to follow, since it follows a linear approach and requirements are made clear in the first phase.

If the application you are planning to develop needs to evolve with each phase and frequent overhauls may be expected in the project, Agile methodology is the best approach to keep up with customer requirements and technology landscape.

Product Visibility to The Customer

When waterfall model is followed, the customer can only see the full product after the project comes to an end and the application is deployed into production.

In Agile, since the duration is split into multiple sprints, customer gets frequent opportunities to look at the product and thereby, take decisions regarding acceptance criteria and changes to be performed.

Working as a Team

The biggest disadvantage of the waterfall model is that it does not allow integrated collaboration between developers and testers. Testers begin their work only after the development phase is over and they work individually.

In Agile, testers and developers work together. Each sprint has a testing phase and every time a new function is released, it is immediately followed by regression testing.

Splitting a Big Task into Smaller Ones

In Waterfall model, software development becomes a bit complex since the entire application is to be completed as one single project. It becomes a hectic job for developers and more hectic for testers when they begin testing a large application.

In Agile, the project gets split up into multiple user stories. Developers and testers work together in each phase to understand the requirements and the customer finally gives a review of whether everything is done correctly. It makes the job easier and quicker.

Pros and Cons of Agile and Waterfall

Waterfall Approach

Although traditional, waterfall model is advantageous in many ways.

• A predictable and static workflow ensures that the team can calculate proper cost estimation and get an idea of deadline.
• Since the process requires documentation, a paper trail leads the way to each development phase. Following the logic of past projects, the team can set groundwork for future projects also.
• The process is straightforward, so no prior knowledge is required by the team in order to start working on the waterfall model.

However, cons are there as well

• Since the model is rigid, any major change can prove to be costly for both the customer as well as the team, since the entire project has to be scrapped off and started again.
• The result of multiple phases of requirement gather, development and testing lead to quite a lot of time before the stakeholders actually get to view the live application.

Agile Methodology

Since it follows an iterative approach, Agile is advantageous in many ways

• Short development phases make the project adaptable and always ready for any major or minor change required by the customer.
• The customer can view the live project during every sprint and regular feedback results in a better-quality product.
• Developers and testers work hand in hand along with the customer. A better teamwork results in the development of an individual as well as business of the organization.

Whenever there are advantages, it is followed by certain disadvantages

• Agile prefers a working application over documentation. This is a good thing but depending on the complexity of a project, a proper balance between documentation and coding may sometimes be necessary
• The methodology is designed for small teams. Therefore, each team member must be proficient in their roles and self-dependent.

Key Takeaway: Waterfall buys a predictable cost and deadline estimate at the price of rigidity, while agile buys adaptability at the price of lighter documentation and a dependence on small, self-sufficient teams.