Pros and Cons of Waterfall Software Development

What is the Waterfall Model?

The waterfall model has existed for over 50 years. It was first described in 1970 by Dr. Winston W. Royce as one of the earliest formal models of the software development process.

We often describe the waterfall as "linear-sequential lifecycle model". This means it has a simple phase structure where the outputs of each phase cascade to the next development level. In other words, it's not one big Niagara Falls, but several cascading waterfalls, each with its own pool of work.

The original Waterfall model consisted of five stages:

• Requirements
• Design
• Implementation
• Verification
• Maintenance

There are several well-recognized waterfall methodologies. One of them is PRINCE2, which was created by the UK government and is still highly regarded in the public sector.

The waterfall is often placed at the opposite end of the software development spectrum from Agile development. One key difference between the two methodologies is that in waterfall development, everything must be described in written documentation before any code is written. With this approach, it is very important that all requirements are thoroughly defined from the start, as they will be difficult to revise later.

What are the pros and cons of waterfall development?

Pros:

• Fast onboarding. Since technical documentation is a necessary part of the initial requirements development phase, everyone understands the goals. New developers can quickly get up to speed - even during the maintenance phase.
• Timeline adherence. The phased development cycle enforces discipline. Each stage has a clearly defined start and end point, making it easy to track progress. This reduces the project's "lag" behind agreed deadlines.
• No financial surprises. Once requirements are defined, costs can be estimated with a fairly high degree of accuracy.
• Testing is simplified. Test scenarios are already detailed in the functional specification during the requirements phase, making the testing process simpler and more transparent.
• The result is crystal clear. Even before software development begins, the design is worked out in detail, making the needs and the outcome clear to everyone.
• Problem solving during design. Potential development issues can be studied and resolved during the design phase, with alternative solutions planned before coding begins.
• What you plan is what you get. Many organizations value the early focus on documentation because it means the final product will hold no surprises.

Cons:

• Needs can be difficult to define. Clients may find it hard to articulate their needs as a functional specification during the requirements phase. This means they may change their mind after seeing the final product, which is hard to fix if the application requires significant redesign.
• Potential lack of flexibility. Issues can arise with the model's flexibility to accommodate new developments or changes in requirements that may occur after the initial consultation. Changes related to business plans or market influences may not be accounted for in advance planning.
• Longer delivery time. Compared to using an iterative methodology like Agile, project delivery may take longer.

Which projects are best suited for waterfall development

When it comes to waterfall development, it is critical that software developers can effectively guide and advise clients to avoid later problems. This is often the most criticized aspect of waterfall development - that the client does not know what they want.

In many cases, genuine two-way communication between developers and clients only begins after the client can see the model in action. (In comparison, Agile development allows the client to see pieces of working code that are built and demonstrated throughout the process.)

Based on these pros and cons, waterfall development is typically recommended for projects where no changes or new developments are expected during the project lifecycle.