Choosing the right development methodology for a project plays a key role in the success of the project. Make the wrong choice and you will often find that the project becomes bogged down in avoidable delays.

In software development, the two most popular methodologies are the “Waterfall” and “Agile techniques.

Waterfall is a linear methodology in which specific tasks, such as gathering documentation, creating a plan, coding, and testing, get separated into individual stages, each usually being given a timeframe for completion and typically preventing progress to the next stage before completion of the current one.

By contrast, Agile is a more collaborative methodology that places quick delivery as a key priority. Instead of individual stages, Agile employs “sprints” in which a set of tasks related to the project are defined and delivered within a set timescale. These tasks may involve every department working on the project concurrently, meaning it is entirely possible for some development to begin while planning for later development is underway. As such, Agile is often seen as a more flexible methodology than Waterfall and it lends itself more readily to iterative software development.

Of course, the key question is which methodology is right for your project. Each has pros and cons to consider before making a choice.

The Waterfall Methodology

As one of the oldest software development methodologies in use today, Waterfall has been refined well and typically includes periodic reviews of the work completed, usually upon conclusion of a stage. This method gives rise to both positives and negatives.

Choosing the right development methodology for a project plays a key role in the success of the project.

The Pros
•    Project progress is easily measurable as all involved understand the schedule and key deliverables in advance of the project’s start.
•    Alignment between clients and project developers occurs at the earliest stages of the development cycle. As such, clients can take a more hands-off approach as the project progresses by taking part in reviews and status updates without having to continually collaborate with developers.
•    The methodology allows for some flexibility. For example, testers can prepare relevant scripts while development is underway using the documentation created in earlier stages.
•    As design is generally a separate stage, Waterfall allows for the intricacies of complex projects to be properly planned out prior to the beginning of development.
•    The risk of having to spend time tinkering with pieces of code to add it into the large project application is reduced as all stakeholders in the project are fully aware of the project’s demands and the technologies used in its creation from the offset.

The Cons
•    Waterfall, by its nature, requires project planners to gather specific details and documentation from the off, which can prove intimidating to clients who have little experience in software development. As such, the methodology raises challenges in terms of helping clients understand what they are actually getting and how the information provided helps the project reach its goals.
•    Changes in project requirements are often difficult to implement, particularly once development is underway, as the entire project is carefully planned based on the documentation and requirements gathered in the early phases.
•    As testing tends to occur as a single stage at the end of the development lifecycle, early bugs go undetected, potentially affecting later code to the point where they create large problems.
•    Projects can end up being delayed if a particular stage is not completed within the expected timeframe, which prevents the next stage from proceeding.
•    Developers can often not go back to the previous stage if an issue is discovered when using the Waterfall methodology. In some cases, a single problem can cause the entire project to go back to the first stage.

The Agile Methodology

Though not as new a concept as some would have you believe, the Agile methodology is increasingly being seen as a replacement for the Waterfall method. However, it has pros and cons of its own.

The Pros
•    Clients are engaged throughout the entire development lifecycle, offering a greater understanding of the work being delivered and allowing for faster decision-making where required. Further, this engagement allows clients to take greater ownership of the project, thus making them more invested in its success.
•    The flexibility of Agile allows for changes in project requirements to be implemented more effectively, thus preventing these changes from holding up other aspects of the development cycle.
•    The iterative nature of Agile allows developers to create more basic versions of software that can be enhanced through later development work, thus allowing clients to begin marketing software earlier and provide it quicker, with later developments enhancing the product for the early user base while making it more attractive to latecomers over time.
•    The increased collaboration at the heart of Agile fosters transparency on the parts of both client and developer.
•    Testing is usually implemented into each Agile sprint, meaning bugs are spotted earlier and thus don’t cause problems later on.

The Cons
•    Not all clients wish to engage in development processes as frequently as Agile requires, which can lead to frustration on the client’s part, resulting in dwindling interest as the project progresses.
•    Agile methodologies can sometimes be more difficult to explain than the Waterfall model, particularly when it comes to the concept of sprints and how the various traditional stages of development intermingle when using Agile.
•    Costs can spiral if certain requirements are not completed within their assigned sprints, with too many missed requirements leading to new sprints being created that delay the project. Further, increased client involvement can have the downside of creating constant changes that lead to higher costs.
•    Poor project management and anything less than full commitment from all stakeholders can scupper Agile development, as disengagement leads to delays. For example, many projects employing Agile find they run into difficulty if the various teams involved in the project are not located within close proximity to one another, thus making the communication that lies at the core of the methodology more difficult.
•    The focus on creating working software quickly can lead to poor documentation of what the end user actually needs to know to use it.

Which Should You Choose?

So now you know about the pros and cons of both development methodologies, you need to figure out which one you should choose.

As a general rule, Waterfall works best for projects that have clearly defined end goals in place that are very unlikely to change during development. Further, Waterfall works well in projects where speed of release is a secondary concern and is often ideal for working with clients who prefer to let the developers do their jobs without having to provide regular input.

Alternatively, Agile is ideal for projects where speed is of the essence and the client is not fully certain of the requirements, which will usually lead to changes being made as the development process goes on. A skilled and adaptable development team is a must and Agile is practically mandatory for industries that evolve quickly, such as streaming services, or when the client wishes to operate a subscription model in delivering the software to users.