This section of tutorial explains rapid application development methodology and its different phases of development with its drawbacks.
Rapid Application Development (RAD) is an incremental software development process model that emphasizes an extremely short development cycle. The RAD model is a high speed adaptation of the linear sequential model in which the rapid development is achieved by using component-based construction. If requirements are clear and well understood and the project scope is constrained, the RAD process enables a development team to create a fully functional system within a very short period of time.
The RAD approach encompasses the following phases:
- Business modeling: Here we try to find answers to questions like what information drives the business process. What information is generated? Who generates it? Where does the information go? Who processes it? Etc.
- Data modeling: Here the information flow which would have been defined as part of the business modeling phase is refined into a set of data objects that are needed to support the business.
- Process modeling: The data objects defined in the data modeling phase are transformed to achieve the information flow necessary to implement a business function. Processing descriptions are created for adding, modifying, deleting, or retrieving a data object.
- Application generation: RAD assumes the use of fourth generation techniques. Rather than creating software using conventional third generation programming languages the RAD process works to reuse existing program components(when possible) or create reusable components(when necessary). In all cases, automated tools are used to facilitate construction of the software.
- Testing and turnover: Since the RAD process emphasizes reuse, many of the program components have already been tested. This reduces overall testing time. However, new components must be tested and all interfaces must be fully exercised.
Drawbacks of the RAD model
- For large but salable projects, RAD requires sufficient human resources to create the right number of RAD teams.
- RAD requires developers and customers who are committed to the rapid-fire acitivites necessary to get a system complete in a much abbreviated time frame. If commitment is lacking from either, RAD projects will fail.
- Not all types of applications are appropriate for RAD. If a system cannot be properly modularized, building the components necessary for RAD will be problematic. If high performance is an issue and performance is to be achieved through tuning the interfaces to system components, the RAD approach may not work.
- RAD is not appropriate when technical risks are high. This occurs when a new application makes a heavy use of new technology or when the new software requires a high degree of interoperability with existing computer programs.
Points to remember before selecting the best software engineering methodology are
- How big is the project?
- Do you need a prototype?
- Are you using a packaged solution?
- How flexible is your team?
- How much will your customer participate in the process?
- Is your project manager experienced?