What Are Waterfall and Agile Models of Development?
The Waterfall software development model has been around since 1956 and has been the typical go-to model for software development for decades. Waterfall model takes a stage-based sequential model of developing a software from conception, planning, execution, testing and release.
While agile software development methodology has also been around for decades, its prominence grew during the 1990s when micromanagement and bulk planning were costing companies time, efficiency and effectiveness of the software being produced using the Waterfall method of development.
Unlike its predecessor, Agile takes a light-weight and flexible approach to software development where the entire software is developed in layers or versions, one building upon the successes of the previous iteration.
Let us now look at the key differences between Waterfall and Agile models of software development:
- Incremental vs sequential development
Out of the box, the most prominent difference between agile and waterfall methods is the use of incremental development in agile and sequential development in waterfall. This means that while agile can split the final product into several versions and deploy the first version faster, waterfall development the entire software and only then deployment/release of the software takes place.
This gives agile an edge in terms of market testing of the different versions of a particular product and making improvements on the original plan. Whereas, waterfall has the edge in faster software development and deployment where developers and clients are sure of the exact model they need and no market testing is needed.
- Lean vs bulk resourcing
Since waterfall sticks to the original scope of work, resource planning and acquisition also needs to be done at once, based on total requirements needed. Once the software is deployed, the teams are relieved from the project.
On the other hand, since agile projects deliver the final version in layered iterations, they can kickstart the project with much leaner teams and scale only as the need comes up.
Scaling in the agile model is more of a long-term solution and once the product is completed, the teams continue till the final iteration is complete based on market and client feedback. Moreover, under continuous development frameworks in the agile model, some teams may choose to never relieve the teams, since the software will continually need improvements as per changing user needs.
- Flexible vs static scope
Waterfall model of development works on a static scope, where the end-to-end scope of work is planned with no room for changes beyond the planning stage. This type of modelling is effective for development of small products such as web-pages and feature additions. In some cases, where extensive research has been done to finalize a product and its features, the waterfall model may prove to be more effective based on client needs.
The agile model relies on end-user and client feedback to deliver a value-based product that meets real needs of customers rather than relying solely on estimations. Therefore, agile is a much more flexible development model where developers actively monitor performance and conduct robust client and end-user feedback to plan and deploy next iterations.
- Customer availability and engagement
Customer availability and engaging them to get feedback on each iteration of the product is a big part of the agile model of development.
This allows developers to respond quickly to changing market scenarios as well as continuously monitoring and responding to competitors and emerging user preferences.
Apart from the advantages, the one aspect that needs to be on the same page early between clients and developers is the need for clients to make themselves available for giving frequent feedback.
This takes up more time on behalf of the client, but the final result is customer satisfaction and continuous engagement to ensure everyone is on the same page and on the desired track.
The waterfall model of development requires client input only in planned milestones for the project, where the product is always in staging environment and never on the final released version (release would mark the end of the project).
Post-release, limited changes can be made, particularly if there are any errors that got passed quality-assurance teams.
Even during engagement with the customer, only changes in user-interfacing and aesthetics are typically entertained, not functional changes.
This process however, reduced the need for client availability and time investment during the development phase.
Key Advantages of Using Agile vs Waterfall Models
Advantages of the Agile model:
- Value-based software development where end-value of the product to the client and their users is the key goal.
- Go-to-market is faster with the first iteration’s deployment.
- More capability to quickly respond to changing market and end-user needs and preferences.
- Reduces chances of any knee-jerk reactions in client relationship management through frequent engagements.
- Highly customer centric which makes it easier for the development team to abide by the larger customer experience delivery framework of the organization.
- Requires less up-front investment
Advantages of Waterfall model:
- Simpler to manage since the scope is pre-defined and unchanging.
- Human resource changes have least effect on the work-pipeline and delivery.
- Highly process and documentation oriented due to its linear stage-based approach.