3.3.1 apid pplication evelopment

What Rapid Application Design is including: – Joint Development Application Workshops (JAD). – Timeboxing The benefits and negatives of RAD.

So far we have looked at the more common approach to system design and the prototyping method. Another method of software design is called Rapid Application Design. Like prototyping, the aim of RAD is to shorten the project duration.

This model of system design must be completed within six months. It is considered that six months is the longest time that a user’s requirements will not change. The RAD approach is different to classic systems life cycles. It involves making a series of prototypes and getting feedback from the end user.

With RAD the end-user is more involved throughout the design process. They evaluate each prototype. After each prototype is evaluated the designers will go back and make improvements to the prototype. This process is repeated until a final product is produced and agreed upon. After each round the process spirals closer to the final product. This is why this model is sometimes called the Spiral Model.

Feasibility Study System Analysis Prototype Testing Installation Maintenance Feedback Prototype Feedback Prototype Feedback

RAD has two main features: – Joint Application Development workshops – Timeboxing

This method of system development has a greater emphasis on end-user involvement. Workshops are created in which the developers and the end-users meet to discuss requirements and assess design solutions. Through these workshops a greater understanding of what the system should do will be established.

The aim is to establish an agreed set of requirements which should not change before the system has been implemented. Although the cost of these sessions are more expensive to run compared to analysis methods, the cost of miscommunication in terms of system requirements is far more costly. If the requirements are not communicated properly and a system has already been implemented the cost of changing the system would be a lot higher than spending more time at the start of the project establishing the requirements.

For more information on JAD check out the article on Wikipedia which looks at what JAD is made up of. There are loads of sites which provide information on JAD…research!

Once the requirements have been established, they can be broken down into ‘chunks’. Each ‘chunk’ of time will have a set of deliverables which must be met. If a deliverable is not met the ‘chunk’ of time is not extended. Instead, the deliverable is moved into a new ‘chunk’ of time.

If deliverables overrun continually then the system as a whole may need to be reviewed. By doing this it prevents over-run deliverables piling up and causing big delays.

RAD allows for continual evaluation of the product to take place. RAD ensures that requirements are understood fully before the system is implemented. The end-users are able to see what the end product would look like and how it would function before any of the functions are actually created. The system is usually created within six months (which is very quick in terms of system development).

The end-users might get confused when they see a prototype that seems to work – they may think that it won’t take as long to create the system as what is projected. The system may work for the small number of people using the system, but when more users are added the system might not be able to cope. Time management is vital and is often very difficult to manage. If timescales start to slip then managing a project through RAD becomes less appropriate.

Define the RAD methodology. Explain what the advantages and disadvantages are compared to other methodologies. Explain what JAD and timeboxing is.