Waterfall Vs Agile – Advantages, Disadvantages and Difference

Waterfall Vs Agile

This article explains the Waterfall model and the Agile model along with the advantages and disadvantages of each. Also, find the difference between them.

The Waterfall methodology and Agile methodology are two different models of the Software Development Life Cycle. The agile model was basically developed to oppose the Waterfall model in the late 1990s. This was because the Waterfall model was too rigid for some developers. The difference between these two models can be summarised in just one sentence. The waterfall is rigid, whereas Agile offers flexibility to the developers. Apart from having the goal of delivering a high-quality and efficient product, they do not have any significant similarity. Hence in this blog, we will focus completely on the difference between the two models.

The Waterfall Model

The Waterfall methodology is the most popular version of the System Development Life Cycle for software engineering and any project involving the Information Technology field. This methodology is known to follow a sequential and linear process. Sometimes, the planning of the waterfall methodology is done with the help of a Gantt chart. This type of bar chart shows the start and end dates for each task. They generally consist of eight stages, and once one of the eight stages is complete, the development team moves into the next step. In the waterfall methodology, the team cannot go back to a previous stage without starting the whole process from the beginning. The team also needs approval and feedback on the requirements of the customer to move to the next step.

Waterfall Model
Peter Kemp / Paul Smith / CC BY

Advantages of the Waterfall Model

Developers take help for the waterfall methodology for simple, unchanging projects. The linear and rigid nature of the model makes it easy to use and allows for in-depth documentation.

The advantages of waterfall methodology include

Easy to use and manage: Since the waterfall model follows the same sequential pattern for all the projects, it is easy to use and understand. The developing team does not need any prior knowledge or training before working on the waterfall model. The rigidity of the model and the need to take reviews from customers before moving onto the next step makes it easy to manage and control.

Discipline is enforced: The team can reduce the risk of missing a deadline by focusing on requirements and design before writing the code of the software. Every phase in the waterfall has an initial and final point, and hence it makes it easy to share the progress of the project to the management team, the stakeholders, and the customers.

Encourages a well-documented approach: There is a need for documentation at every phase in waterfall methodology, which results in a better understanding of the logic behind the codes and tests being used. It further leaves a paper trail for any upcoming projects, or its stakeholders need to see more detail about a specific phase.

Disadvantages of Waterfall Model

The most significant disadvantage of waterfall methodology is how it handles change. The waterfall is a linear and sequential model; the developing team cannot bounce between two phases, even if some unexpected changes occur. Once a phase is done, that’s it

The disadvantages are as follows-

The developers cannot comfortably accommodate changes – the team can’t go back once the team completes a particular phase. After reaching the testing phase and then realizing that a specific feature was missing from the requirements phase, it becomes challenging and costly to go back and fix it.

The team cannot deliver the software until late: according to the rigid pattern of waterfall methodology, that developing team has to complete 2 – 4 phases before actually starting the coding work. As a result, the stakeholders and customers cannot see working software until late in the life cycle.

Gathering specific requirements can be tricky – the first phase in the waterfall project is to interact with customers and stakeholders and identify their needs. However, it becomes difficult to conclude exactly what the customers are the stakeholders want early in the project. Often the customers are not so ever of what they want at the beginning and instead learn and identify their needs as a project progresses.

The Agile Model

The agile methodology is one of the most popular models of the Software Development Life Cycle. This methodology promotes continuous iterations throughout the software development life cycle of the project. Unlike the waterfall model, in agile methodology, the testing activities and the development can go hand in hand.

The evolution of the agile model can be traced back to the 1990s as a result of different light with the software process. The reason for its popularity among project managers is that many of them disapproved of rigid, linear waterfall methodology. The agile method mainly focuses on flexibility and continuous improvement with speed.

Agile Model
Kokcharov / CC BY-SA

Advantages of the Agile Model

Following are some of the most admired advantages of agile –

The Agile model encourages changes: The life cycle short enough to accommodate and accept changes at any time during the project efficiently. There is always a chance to refine and reprioritize the backlog, allowing the teams to introduce changes in the project in a matter of weeks.

The end goal can be unknown: Developers use the agile methodology for projects in which the end goal is not clearly defined. Is the project progress is, goals will become a clear ear, and the development can quickly adapt to the evolving requirements?

Quicker, high-quality delivery: In an agile model, the project is broken down into iterations, which are small manageable units that do allow that team to focus on quality development, testing, and collaboration.

Strong team interaction: Agile encourages frequent communication and phase to phase interaction among the team members involved in a particular project. In this method, teams generally worked together, and people can take responsibilities and own parts of the project.

Better interaction with customers: Customers are given a good number of opportunities to see the work being delivered, share their opinions, and that how they can have a real impact on the end product. They are also giving a sense of ownership by working so closely with the project team.

Continuous improvement of the product: Agile projects encourage the users and team members to give feedback throughout the project. Here, developers can use lessons learned can improve future iterations.

Disadvantages of the Agile Model

While the level of flexibility in agile is usually a positive thing to look at, but it also has some drawbacks. Some of the disadvantages are-

Less concrete planning: Many times, it is hard to choose a reliable delivery date. Since agile is based on time minus box delivery and project managers often reprioritized the tasks, there is a good chance that some items which are original schedule for distribution may not be complete in time.

Team members must be knowledgeable: The agile teams are generally small, show the team members should be highly skilled in a variety of fields. They should also have in-depth knowledge and feel comfortable with the chosen agile methodology.

Time commitment from the entire team: Generally, successful only when the development team completely dedicate their time and efforts to the project. Active involvement from each member is essential throughout the agile process, which makes it more time consuming as compared to the waterfall method.

Difference between Agile Model and Waterfall Model

Agile Model Waterfall Model
The agile method proposes an iterative approach to software design The development of the software flows sequentially from the start point to the endpoint.
Generally, the developers break the agile process  into individual models that designers work on The developers do not break the design process into individual small models.
The customer has early as well as frequent chances to look at the product and make a decision and changes in the project. The customer can merely see the product at the conclusion of the project.
Experts consider the agile model to be unstructured as compared to the waterfall model. The waterfall model is more protected because they are very much plan oriented.
The team can implement small projects quickly. For large projects, it is complicated to estimate development time. The team can estimate all dimensions of the project and complete them.
Developers can fix the error can in the middle of the project. Only at the end, the developers test the whole product. If they find any requirement error or any required changes, the project has to start from the beginning.
The development process is iterative, and the given project is executed in short (2-4) weeks iterations. Planning is considerably less. The development process is phased, and, at the same time, the phase is much bigger than the iteration. Every step ends with a detailed description of the next step.
Documentation gets less priority than software development. Documentation is always a top priority, and the team can even use the documentation for training staff and improve the software with another team
Every iteration has its testing phase. It allows implementing failure testing every time the developer’s team releases the latest functions or logic. The team executes the testing only after the development phase because individual parts are not fully functional.
In agile testing, when an iteration ends, shippable features of the product are delivered to the customer. New features are usable right after the consignment. It is practical when you have a good relationship with customers. All the features developed by the team are delivered at once after the long execution step.
Testers and developers work collectively Testers and  don’t work together
At the end of every sprint, the Developer team has to take user approval. The developer team takes user approval at the end of the development.
It needs close communication with developers and together examines requirements and planning. The developer does not engage in the requirement and planning process—usually, time delays between tests and coding.

I hope you find this guide useful. If so, do share it with others who are excited to explore Software Engineering and other topics that we publish here on our blog. If you have any questions related to this article, feel free to ask us in the comments section.

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