(Rapid Application Development Model)
Builds on the Incremental model with emphases on short development cycle. In other words high speed waterfall model
Components are build using this model as a fully functional units in a relatively short time It assumes that the system can be modularized
RAD will fail if you don’t have strong and skillful teams High performance might be an issue
The Phases of RAD Model
The information flow among business functions is modeled in a way that answers the following questions: What information drives the business process?
What information is generated?
Who generates it?
Where does the information go?
Who processes it?
The information flow defined as part of the business modeling phase is refined into a set of data objects that are needed to support the business. The characteristics (called attributes) of each object are identified and the relationships between these objects defined 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. Drawbacks of RAD Model
For large but scalable 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 activities necessary to get a system complete in a much abbreviated time frame. If commitment is lacking from either constituency, 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 heavy use of new technology or when the new software requires a high degree of interoperability with existing computer programs. Q) Spiral model for Software development [D-2011]
..with merits and demerits.[D-2012]
Ans: Iterative (like Prototype) and controlled (like waterfall) model. Software is developed using evolutionary releases
Software complexity increase with each release
Consist of 6 task regions.
1.Customer communication - the goal is to establish good communication between customer and developer. 2.Planning - produce/adjust project plan.
3.Risk analysis - assess management and technical risks.
4.Engineering - build one or more representations of the application. 5.Construction and release - - to construct, test, install and support the application. 6.Customer evaluation – get customer feedback.
Evolutionary Models: The Spiral
When to Use the Spiral Model
Very large projects.
When technical skills must be evaluated at each step.
Q)Discuss waterfall Model with merits and demerits..[D-2012] Ans:
This Model suggests a systematic, sequential approach to SW development that begins at the system level and progresses through analysis, design, code and testing.
Limitations of the waterfall model
oThe model implies that you should attempt to complete a given stage before moving on to the next stage Does not account for the fact that requirements constantly change. It also means that customers can not use anything until the entire system is complete. oThe model makes no allowances for prototyping.
oAssumes understanding of problem and full requirements early on oIt implies that you can get the requirements right by simply writing them down and reviewing them. oInflexible partitioning of the project into distinct stages makes it difficult to respond to changing...