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Compare Waterfall, Prototyping, Incremental and Agile Development Processes

Joseph Gulla
 

Application software has a defined lifecycle. It begins with an idea or a list of requirements, and ends when the application is replaced or no longer used (i.e., “being sunset”). A key subset of the software lifecycle is the development process—a method used to create applications. The development steps can be formal and well defined, often called a process, or more general in nature, called an approach. The term framework is used in both relaxed and more formal procedures.

Many processes, approaches and frameworks support software development, including waterfall, prototyping, incremental, spiral, rapid, extreme and agile. These terms are all related to one another in subtle ways. Each can be explained by describing its basic operation and principles, as well as its fit for specific projects based on a number of factors. Consider these three dynamics:

  • Team maturity and experience: Some approaches work better for less experienced teams, whereas others require expert teams
  • Organizational participation: Some frameworks are a good fit for organizations that choose to have high organizational participation, whereas others work best when teams are autonomous
  • Project size: Some processes favor minor efforts, whereas others are best for large and complex projects

These aren’t the only factors to consider. This article examines the benefits and challenges of the waterfall, prototyping, incremental and agile development processes.

 

Waterfall

The main ideas behind the waterfall framework were borrowed from engineering because it was clear from the beginning that the complexity of software development could benefit from an orderly approach. The hallmark of the waterfall model is a sequential development approach featuring several phases with names like requirements, design, coding, testing, integration, installation and maintenance. Its important aspects are careful planning, managing time schedules and dates, and keeping to the budget for an entire application or business system.

Many organizations have moved away from the waterfall model, but it’s still a good fit for less experienced teams or teams whose composition fluctuates because, by design, they’re helped by the broader organization through the life of the project. It’s attractive because of its focus on order and predictable progress. The waterfall model is sometimes used in conjunction with other methods, such as prototyping.

Waterfall projects have certain strengths. For instance, it can be easy to measure progress by proven metrics like tracking planned versus actual task starts and completes from a comprehensive project plan. It is also easier for less experienced staff to handle. Because the model uses milestones as a metric, they are well understood by teams. The waterfall framework also facilitates strong management control. The method works best when quality of the work product is more important than cost or schedule.

The waterfall model has its weaknesses: It’s easy to start tasks and harder to complete them, so keeping an eye on the revised “estimated hours to complete” for tasks is important for the project manager. Project controls like reviews, meetings, documents and reports can result in high development costs. The time gap between design and testing phases means problems in design can be found well after that phase is completed. Also, design specifications are technical and targeted at developers, not end users.

Prototyping

The idea behind the prototyping approach is to create a partial version of the software application. This technique can result in breaking the large application into smaller parts involving one or more prototypes, with the goal of reducing risk. The iterative approach used with the prototype can reveal subtle but necessary dimensions of the application’s processing and use.

Joseph Gulla is the IT leader of Alazar Press, an imprint of Royal Swan Enterprises. Previously, he was an executive IT specialist at IBM ending his 28-year career with the company in August 2012.


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