3.3.1
description
Transcript of 3.3.1
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R
A D
3.3.1
apid
pplication
evelopment
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This presentation covers
• What Rapid Application Design is including:– Joint Development Application Workshops (JAD).– Timeboxing
• The benefits and negatives of RAD.
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Introduction
• 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.
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Rapid Application Design• 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.
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Rapid Application Design• 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.
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Waterfall model with RAD
Feasibility Study
System Analysis
Prototype
Testing
Installation
Maintenance
Feedback
Prototype
Feedback
Prototype
Feedback
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Features of RAD
• RAD has two main features:
– Joint Application Development workshops
– Timeboxing
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Joint Application Development (JAD)
• 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.
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Joint Application Development (JAD)
• 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.
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Joint Application Development (JAD)
• For more information on JAD check out the article on Wikipedia which looks at what JAD is made up of.
http://en.wikipedia.org/wiki/Joint_application_design
There are loads of sites which provide information on JAD…research!
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Timeboxing
• 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.
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Timeboxing
• 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.
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Benefits of RAD
• 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).
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Negatives of RAD
• 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.
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What you need to be able to do
• Define the RAD methodology.
• Explain what the advantages and disadvantages are compared to other methodologies.
• Explain what JAD and timeboxing is.