What is rapid application development?

Because rapid application development eschews costly planning and regimented linear models in favor of an approach in which changes can be made during any development stage, it is often grouped together with Agile development. But while RAD incorporates many Agile principles, it is not the same thing.

Agile focuses on breaking projects down into features built during sprints (short periods where a team works to complete a predetermined set of tasks), creating multiple iterations designed to produce feedback as each feature is completed. RAD, on the other hand, places greater focus on prototypes—usable versions of the complete product that can be shared with the user to generate more feedback relevant to the entire app. Rather than waiting for individual features to be completed before seeking user assessment, RAD delivers prototypes still in the development phase so that full functionality may be improved throughout the entire process.

To do this, RAD relies on an extensive repository of reusable code to create and release prototypes quickly, so that the development process remains focused on creating and refining usable software.

Due to its focus on building working prototypes for users to test and evaluate, rapid application development brings with it several advantages over other software development methodologies. These benefits include:

• Development can easily pivot to accommodate changing project requirements.
• Release versions can be produced quickly without the need to create or plan for large development cycles—RAD tools help speed the process.
• Progress between prototypes is easy to track and measure.
• Reusable code reduces the likelihood of errors and cuts down on the necessary testing times.
• Reducing time to market and eliminating the possibility of needing to rerun projects, RAD allows development teams to accomplish more at lower cost.
• Customer feedback is encouraged as the primary testing method, improving user involvement to achieve a more effective product.
• Risks may be discovered and addressed early in the process, rather than being put on hold until the definitive version of the software is nearing completion.
• Software integrations are built into the application throughout the development process, ensuring that the final product is capable of functioning optimally with other tools and systems.
• New technologies may be incorporated as they emerge—even mid-development.
• Versions may be released quickly and without significant effort, reducing the time to market of essential applications.
  

Despite its many benefits, there are some disadvantages to be aware of when considering the RAD model. These may include:

• RAD depends heavily on highly trained and experienced team members to identify business requirements and create working models.
• Larger teams or projects with too many stakeholders may be incapable of collaborating effectively or embracing the flexibility needed for rapid application development.
• RAD is only appropriate for systems that can be effectively modularized.
• User requirements must be clearly defined throughout the project lifecycle.
• The high cost of modelling and automated code generation can make RAD prohibitively expensive when applied to lower-budget projects.
• RAD is best suited to projects that require shorter development times; long-term projects may benefit from other methodologies.
  

With the above disadvantages in mind, it’s clear that rapid application development is best suited for projects that have a large and responsive pool of users that are committed to testing the application and providing detailed feedback. At the same time, organizations need teams of highly skilled and motivated developers to quickly fulfill requested changes to ensure that new prototypes are being rolled out quickly. Projects or scenarios that fall outside of these requirements may be poorly suited for rapid application development.

To ensure effective RAD results, consider the following best practices:

• Make sure that there is enough budget to cover costs, particularly those associated with automated code generation tools.
• Have available domain experts on hand to provide the necessary business knowledge.
• Apply RAD only to projects that can be easily broken down into specific modules; those that cannot be modularized may not benefit from RAD.
• Consider RAD for projects with non-static requirements to address changing needs smoothly via prototypes presented directly to users on a regular basis.

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