The RAD (Rapid Application Development Model) model is proposed when requirements and solutions can be modularized as independent system or software components, each of which can be developed by different teams. After these smaller system components are developed, they are integrated to produce the large software system solution. The modularization could be on a functional, technology or architectural basis.
RAD becomes taster if the software engineer uses components technology such that the components are really available for reuse. Since the development is distributed into component development teams, the teams work in tandem and total development is completed in a short period (i.e., 60 to 90 days). Figure shows the RAD model.
- Business Modelling : It covers the following functions :
- Where does information come from and go ?
- Who processes it ?
- What information driven the business process ?
- What information is generated ?
- Data Modelling : The information flow defined as part of the business-modelling phase is refined into a set of data objects that are needed to support the business. The characteristics of each object are identified and the relationships between these objects are defined.
- Process Modelling : In this model information is flow from object to object to implement a business function. To add, modify, delete or retain a data object, there is a need of description which is done in this phase.
- Application Generation : RAD assumes the use of fourth generation techniques, the RAD process works to reuse existing program components or create reusable To facilitate the construction of the software using above cases, automated tools are used.
- Testing and Turnover : In this we have test the programs, but we use some already existing programs which are already tested, so the time involve in testing is less. Only the new program or components must be tested.
Drawbacks of RAD Model
The various drawbacks of RAD model are discussed as follows :
- If a system cannot be properly modularized, building the components necessary for RAD will be problematic.
- For large, but scalable projects, RAD requires sufficient human resources to create the right number of RAD teams.
- If high performance is an issue, and performance is to be achieved through turning the interfaces to system components, the RAD approach may be work.
- RAD may not be appropriate when technical risks are high (for example, when a new application makes heavy use of new technology).
- If developers and customers are not committed to the, rapid-fire activities necessary to complete the system in a much abbreviated time frame, RAD projects will fail.
Comparison of Various Process Model
The comparison between various process models are depicted in the table below :
Table. Comparison of Process Models