Conceived in the 1980s, rapid application development, or RAD, was the first development methodology to challenge traditional waterfall development practices. Though often mistaken for a specific model, rapid application development is the idea that we benefit by treating our software projects like clay, rather than steel.
Software is a unique engineering structure because it is transient. With traditional engineering projects like bridge construction, engineers cannot begin to build a bridge then change their minds half way through the process—that’s pure chaos. But a bridge built in software? Engineers can change that every day. RAD takes advantage of this by emphasizing rapid prototyping over costly planning.
Brief History of Rapid Application Development
Three quarters into the previous century, humanity began to want software. Fulfilling this desire required developers. These software projects consumed months of laborious planning and even more in development—just like traditional engineering projects. Software architects worked with end-users to draft functional requirements, then spent countless hours defining them in spec sheets.
With specifications prepared, development began. Anywhere from months to years later, users got their first glimpse of the product they themselves requested. And if it failed to meet their expectations, the engineers would refactor—the costs of which were extraordinary.
This process, which began with the blackboard, moved to spec sheet, then to software, and terminated at the user, is known colloquially as the “waterfall” approach. It mirrored traditional engineering assignments that worked with immutable materials like wood, cement, and iron — once set and paid for, these resources were costly to alter.
In the 1980s, Barry Boehm, James Martin and others recognized the obvious: software was not a raw mineral resource. They saw software for what it was: infinitely malleable. Boehm and Martin took advantage of software’s inherent pliability when designing their development models: the Spiral Model and the James Martin RAD model, respectively. Since then, RAD has evolved to take on other forms and acted as a precursor to agile.
Rapid Application Development vs Agile
Those who research development methodologies compare one framework to another. Most commonly, rapid application development is directly contrasted with agile. Unfortunately, this comparison is challenging to draw. RAD is a forbear of agile, but agile encompasses far more than a development model. It is more of a philosophy than methodology.
In an attempt to show this, we have contrasted the core principals of each concept:
|Customer satisfaction by early and continuous delivery of valuable software||This is a core principle of RAD|
|Welcome changing requirements, even in late development||Also found in RAD practice|
|Working software is delivered frequently (weeks rather than months)||Specific time-frames are not recommended by RAD though speed is clearly emphasized|
|Close, daily cooperation between business people and developers||No direct equivalent in RAD, but feedback from end-users is critical to the RAD process|
|Projects are built around motivated individuals, who should be trusted||RAD has no opinion on the makeup of individual team members|
|Face-to-face conversation is the best form of communication (co-location)||RAD has no opinion regarding locality of team members|
|Working software is the primary measure of progress||RAD focuses on delivering working software as frequently as possible|
|Sustainable development, able to maintain a constant pace||RAD offers no opinion regarding the pace of development other than “rapid”|
|Continuous attention to technical excellence and good design||RAD principles focus on functionality and user satisfaction; quality of design and implementation are unnecessary, but ideal byproducts|
|Simplicity—the art of maximizing the amount of work not done—is essential||Here again, RAD does not emphasize reduction of work, but proclaims that RAD projects will require less work in the long term|
|Best architectures, requirements and designs emerge from self-organizing teams||RAD does not limit itself to a team structure|
|Regularly, the team reflects on how to become more effective and adjusts accordingly||Not necessary or inherent to RAD practices|
As you can see, agile took several steps beyond the scope of RAD. While agile dictates the ideal working environment (just shy of how many rubber ducks to keep on your desk), RAD focuses on how to build software products for your clients and end-users. Let’s take a closer look at what RAD entails.
Rapid Application Development Methodology
Though exact practices and tools vary between specific RAD methodologies, their underlying phases remain the same:
1. Define Requirements
Rather than requiring that you spend months developing specifications with users, RAD begins by defining a loose set of requirements. We say loose because among the key principles of rapid application development is the permission to change requirements at any point in the cycle.
Instead of committing to hard and fast specifications, developers gather the product’s “gist.” The client provides their vision for the product, and comes to an agreement with developers on the requirements that satisfy that vision.
In this rapid application development phase, the developer’s goal is to build something that they can demonstrate to the client. This can be a prototype that satisfies all or only a portion of requirements (as in early stage prototyping).
This prototype may cut corners to reach a working state, and that’s acceptable. Most RAD approaches have a finalization stage at which developers pay down technical debts accrued by early prototypes.
3. Absorb Feedback
With a recent prototype prepared, RAD developers present their work to the client or end-users. They collect feedback on everything from interface to functionality—it is here where product requirements may come under scrutiny.
Clients may change their minds or discover that something that seemed right on paper makes no sense in practice. Clients are only human, after all. With feedback in hand, developers return to some form of step 2: they continue to prototype. If feedback is strictly positive and the client is satisfied with the prototype, developers can move to step 4.
4. Finalize Product
During this stage, developers may optimize or even re-engineer their implementation to improve stability, maintainability, and a third word ending in ‘-ility.’ They may also spend this phase connecting the back-end to production data, writing thorough documentation, and doing any other maintenance tasks required before handing the product over with confidence.
Both Boehm’s Spiral Model and James Martin’s RAD Model make use of these four steps to help development teams reduce risk and build excellent products. However, RAD has its drawbacks as well.
RAD: Advantages and Disadvantages
We’ve covered some advantages of RAD already, but let’s restate them and expand.
|Speed||In the traditional waterfall approach, developers were unlikely to go on vacation after delivering the product. Clients would invariably request changes ranging from interface to functionality after first delivery. With RAD, projects are more likely to finish on time and to the client’s satisfaction upon delivery.|
|Cost||In rapid application development, developers build the exact systems the client requires, and nothing more. In waterfall, IT risks building and fleshing out complex feature sets that the client may choose to gut from the final product. The time spent building zombie features can never be recovered, and that means the budget spent on them is lost. RAD reduces this risk and therefore reduces the cost.|
|Developer Satisfaction||In the traditional waterfall approach, developers work in silos devoid of feedback and positive affirmation for a product well-made. And when they finally get the opportunity to present their work to the client, the client may not roll out the red carpet for them. Regardless of how proud developers are of their work, if the client isn’t satisfied, developers don’t receive the accolades they so desperately seek. In RAD, the client is there every step of the way and the developer has the opportunity to present their work frequently. This gives them the confidence that when the final product is delivered, their work receives appreciation.|
Those advantages sound pretty rosy, so let’s douse this warm positivity with a cold splash of reality.
|Scale||A close-knit team of developers, designers, and product managers can easily incorporate RAD practices because they have direct access to one another. When a project expands beyond a single team or requires inter-team communication, the development cycle invariably slows and muddles the direction of the project. Simply put, it’s difficult to keep a large group of people on the same page when your story is constantly changing.|
|Commitment||In waterfall, the client spent most of their time apart from the development team after completing specifications. This allowed clients to focus on their primary tasks and developers to focus on building. In RAD, the frequent cycle of prototypes requires developers and clients to commit to frequent meetings that, on the outset, may appear to consume unnecessary cycles.|
|Interface-Focus||RAD methodology motivates developers to find the perfect solution for the client. The client judges the quality of the solution by what they can interact with—and often, all they interact with is a facade. As a consequence, some developers forego best practices on the back-end to accelerate development of the front-end-focused prototype. When it’s time to deliver a working product, they patch up the jerry-rigged server code to avoid a refactor.|
With the pros and cons of rapid application development laid out, we can determine which types of projects benefit most from RAD, and which do not. If you need to build an internal business tool or even a customer-facing portal, like an app or website, RAD techniques will help your team deliver a better experience to your end-user.
However, if you are tasked with building mission-critical software (flight controls, implant firmware, etc.), a RAD approach is not only inappropriate, it may also be irresponsible. A pilot with a failing control module or a heart attack survivor with a malfunctioning pacemaker cannot provide prototype feedback from beyond the grave.
Tools for Rapid Application Development
As you may now understand, rapid application development is more of a software development methodology rather than a specific language, tool, or interface. However, tools can help facilitate rapid design, development, and feedback solicitation.
Design and Prototyping Tools
The products in this category help teams craft interactive designs at impressive speeds. And some tools on this list, like Webflow, allow designers to export the completed design as a functional cross-browser prototype.
|InVision||Web, Mobile, Wearable||macOS|
|Mockplus||Web, Mobile||macOS, Windows|
|Balsamiq||Web, Mobile||macOS, Windows|
|Adobe Experience Design||Web, Mobile||macOS, Windows|
|JustInMind||Web, Mobile, Wearable||macOS, Windows|
|Proto.io||Web, Mobile, Wearable||Web|
User Testing and Feedback Tools
As noted many times thus far, RAD methodology requires frequent feedback from clients and end-users. And in modern workflows, developers who work offsite prefer to solicit feedback remotely rather than book travel and accommodations each and every time they require input from clients.
|Red Pen||Web, Mobile||Clients|
|Usability Sciences||Web, Mobile||End-Users|
|Validately||Web, Desktop, Mobile||End-Users|
If your team has strict technology requirements or a limited skill set, it’s simpler to stick with what they know. Often you cannot justify the cost of migrating technologies. But if you’re willing to consider a new approach to development, the tools in this category will accelerate your production cycle.
Low-code tools, for example, bundle development elements (IDE, APIs, languages, framework, UI components, connectors, etc.) into a single coherent suite of tools for building applications visually, integrating them with the back-end, and then managing the app lifecycle. No-code tools, by contrast, offer self-service application assembly for business users who are not developers.
|Salesforce AppCloud||Web, Mobile||No-Code, Low-Code, SDK|
|Alpha Software||Windows, Web, Mobile||Low-Code|
|Visual LANSA||Windows, Web, Mobile||Low-Code|
|Spring||Desktop, Web, Mobile||SDK|
|Kony||Web, Mobile||Low-Code, SDK|
|OutSystems (you are here!)||Web, Mobile||Low-Code, SDK|
How OutSystems Enables Rapid Application Development
We are an application platform as a service, or aPaaS. And that means our product goes beyond enabling rapid application development by including hosting, dynamic scaling, release automation, performance monitoring, user management, version control, and much more. But at the core of our offering lies a powerful development environment. Our tool enables everyone from IT-adjacent roles to veteran IT professionals to build enterprise-grade web and mobile applications without code. And as with all low-code tools, seasoned developers may append our front-end and back-end implementations with their own scripts.