Rapid Application Development (RAD) model

Question: What is Rapid Application Development (RAD) model? Explain it.
Answer. “Rapid Application Development (RAD) is a development lifecycle designed to give much faster development and higher-quality results than those achieved with the traditional lifecycle. It is designed to take the maximum advantage of powerful development software that has evolved recently.” James Martin

RAD is a linear sequential software development process model that emphasis an extremely short development cycle using a component-based construction approach. If the requirements are well understood and defines, and the project scope is constraint, the RAD process enables a development team to create a fully functional system with in very short time period.

In short, RAD is a process through which the development cycle of an application is expedited. Rapid Application Development thus enables quality products to be developed faster, saving valuable resources.

RAD model has the following phases:
1. Business Modeling: The information flow among business functions is defined by answering questions like what information drives the business process, what information is generated, who generates it, where does the information go, who process it and so on.
2. Data Modeling: The information collected from business modeling is refined into a set of data objects (entities) that are needed to support the business. The attributes (character of each entity) are identified and the relation between these data objects (entities) is defined.
3. Process Modeling: The data object 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.
4. Application Generation: Automated tools are used to facilitate construction of the software; even they use the 4th GL techniques.
5. Testing and Turn over: Many of the programming components have already been tested since RAD emphasis reuse. This reduces overall testing time. But new components must be tested and all interfaces must be fully exercised.

What are the advantages and disadvantages of RAD?
RAD reduces the development time and reusability of components help to speed up development. All functions are modularized so it is easy to work with.

For large projects RAD require highly skilled engineers in the team. Both end customer and developer should be committed to complete the system in a much abbreviated time frame. If commitment is lacking RAD will fail. RAD is based on Object Oriented approach and if it is difficult to modularize the project the RAD may not work well.

References:

http://ezinearticles.com/?Rapid-Application-Development-Model-(RAD)&id=412312

http://www.casemaker.com/download/products/totem/rad_wp.pdf

http://www.softdevteam.com/RAD-lifecycle.asp