Farewell to waterfalls? - rapid application development - includes product directory

Software Magazine, May, 1995 by Mary Hanna

Today, few companies can afford to use the time-consuming waterfall model for their software development. With the waterfall model, the development team has to complete each development stage before moving on to the next. Some observers say the massive specifications associated with this development approach are simply not practical anymore; organizations want to "code and go."

Perhaps this explains why rapid application development (RAD) has become so popular. "Companies can no longer afford the six-month requirements collection phase that was typical of older development methodologies," said Burt Rubenstein, vice president, technology services at Cambridge Technology Partners (CTP), a consulting and systems integration firm in Cambridge, Mass. "The frameworks and tools available today allow developers to work without having to know all the details of an application. RAD is the natural way to do things."

The ability to deliver quickly can mean success for a development effort. "It is important to get something up and running quickly," Rubenstein said. "We have found that projects that last longer than six to nine months risk either the loss of the user's interest or a change in the business process itself. If more features or enhancements are needed, they can be added in a later phase of the project."

Today, RAD is an iterative approach to development that delivers working pieces of an application incrementally, all the while incorporating feedback from end users. According to Carma McClure, vice president of research, Extended Intelligence Inc., Chicago, rapid prototyping coincided with the advent of Case tools and code generators. As tools became more sophisticated, she said, the process became more iterative.

RAD, and the iterative process, are "more popular than ever," said McClure. "Users want to see something and the sooner they can, the more comfortable they are."

Still, she cautioned, RAD is not always the way to proceed. If developers know a great deal about the systems they are about to build, the waterfall model remains the better bet. "If you know everything up front, waterfall is better. If you're going to 'discover,' RAD is better."

Driving the RAD phenomenon are visual, point-and-click programming tools that allow users to develop GUIs quickly. It is in the area of GUI development that RAD has hit its stride. "If you're talking about the generating of user interfaces, then RAD is very widespread," said Tony Picardi, group vice president, worldwide software at International Data Corp. (IDC), Framingham, Mass. "If you think RAD means automating the entire application from specifications, then it's not that widespread."

Low-end GUI builders, said Picardi, are not adequate for automating event logic and state transition logic. Developers who attempt to use such tools for the entire life cycle end up doing some hand-coding, he said.

Get Users Involved

Still, while some observers maintain that RAD should remain in the coding sphere, others believe it is possible to speed up the entire development life cycle, from requirements gathering to construction.

A typical RAD project for CTP, said Rubenstein, includes a week of "scoping," a three-week joint application development workshop to determine the business case for the system, and six to nine months for application development. This time frame is sufficient for developing a system of medium complexity, such as a decision support system (DSS), a customer service system or a trading system, he said.

The fast pace of development means that a consultancy's ability to work with the customer "on the fly" is crucial. Until they see working models of applications, many end users don't really know what is possible, said Jim Henry, principal at FrontEnd Systems Inc., Fairfax, Va., a consulting and training firm that sells a class library. "User requirements are more well-defined when a good analyst works along with the users and observes how they operate. Once the business rules of the system are understood, the actual processing details are not needed immediately. These can evolve over time."

FrontEnd uses its own class library with SQLWindows from Gupta Corp., Menlo Park, Calif., for development projects. "Our class library provides standard GUI objects, tables and forms with transaction frameworks, which include features such as commitment control and rollback," said Henry. "Developers have only to code in the special validations they need to complete the application."

Using these tools, Henry said he has developed complex applications, including an online bank loan origination and collections system, and a hospital management system that can service 300 simultaneous users.

Like FrontEnd and CTP, Adage Systems International Inc., Westport, Conn., uses RAD techniques to collect system requirements as well as for later phases. Adage develops manufacturing and distribution software. "Our methodology includes RAD techniques in the analysis and design phases as well as in the construction or development phase," said Adage Director Dave Phelan. Development comprises three phases: The first is the design phase, or the rapid prototyping of data models and database. The second is the development stage, which means coding the front and back ends and completing the first level of testing. The final phase is deployment, which includes documentation, script development, development of utilities to generate back-end tables, packaging and product release.