PrototypingPrototyping

By: Michael McBee & Shere StewartBy: Michael McBee & Shere Stewart

PrototypingPrototyping

What is Prototyping?What is Prototyping?

It is an iterative process involving analysts and It is an iterative process involving analysts and users where a model of the proposed system is users where a model of the proposed system is built then rebuilt according to user feedback.built then rebuilt according to user feedback.

Why build a prototype?Why build a prototype?- Visuals may enhance user feedbackVisuals may enhance user feedback- Reminder of requirementsReminder of requirements (ie. Bank Website)(ie. Bank Website)

Prototyping processPrototyping process

Establishprototypeobjectives

Defineprototype

functionality

Developprototype

Evaluateprototype

Prototypingplan

Outlinedefinition

Executableprototype

Evaluationreport

When Do You When Do You Prototype?Prototype?

WHEN DO YOU PROTOTYPE?WHEN DO YOU PROTOTYPE? BEFORE THE BEGINNINGBEFORE THE BEGINNING IN THE BEGINNINGIN THE BEGINNING AFTER THE BEGINNINGAFTER THE BEGINNING IN THE MIDDLE STAGESIN THE MIDDLE STAGES IN MIDDLE AND LATER STAGESIN MIDDLE AND LATER STAGES IN THE LATER STAGESIN THE LATER STAGES

What are Prototypes used for?What are Prototypes used for?

• Learning.Learning. How well does it meet the How well does it meet the customer needs?customer needs?

• Communications.Communications. Help to visual the Help to visual the product or key components.product or key components.

• Integration.Integration. Ensure that the Ensure that the components work together as planned.components work together as planned.

• Milestones.Milestones. Illustrate that the product Illustrate that the product has reached a certain level of has reached a certain level of functionality.functionality.

When Prototyping Is Most When Prototyping Is Most UsefulUseful

User Requirements are not clearUser Requirements are not clear Users and other stakeholders Users and other stakeholders

involvedinvolved Complex designs require concrete Complex designs require concrete

specsspecs Communication problemsCommunication problems Tools availableTools available

Drawbacks of Drawbacks of PrototypingPrototyping

Informal documentationInformal documentation Idiosyncrasies with initial usersIdiosyncrasies with initial users Ignoring external integrationIgnoring external integration

Types of PrototypingTypes of Prototyping

EvolutionaryEvolutionary ThrowawayThrowaway PaperPaper

Evolutionary Evolutionary prototypingprototyping

Specification, design and implementation Specification, design and implementation are inter-twinedare inter-twined

The system is developed as a series of The system is developed as a series of increments that are delivered to the increments that are delivered to the customercustomer

Techniques for rapid system development Techniques for rapid system development are used such as CASE tools and 4GLsare used such as CASE tools and 4GLs

User interfaces are usually developed User interfaces are usually developed using a GUI development toolkitusing a GUI development toolkit

EvolutionaryEvolutionary

Build prototypesystem

Develop abstractspecification

Use prototypesystem

Deliversystem

Systemadequate?

YES

N

Throw-away Throw-away prototypingprototyping

Discard prototype, build product from scratchDiscard prototype, build product from scratch Can use special “prototyping technologies” Can use special “prototyping technologies”

to build quick prototypesto build quick prototypes Don’t have to design prototype carefullyDon’t have to design prototype carefully Coding can be more freestyle and Coding can be more freestyle and

unconstrainedunconstrained Need to redo all the workNeed to redo all the work

Throw-away Throw-away prototypingprototyping

Outlinerequirements

Developprototype

Evaluateprototype

Specifysystem

Developsoftware

Validatesystem

Deliveredsoftwaresystem

Reusablecomponents

SummarySummary

Clearly define the purpose…Why?Clearly define the purpose…Why? What are you approximating (and What are you approximating (and

not)?not)? Determine the form of the prototype.Determine the form of the prototype. Determine cost, construction plan.Determine cost, construction plan. Test, gather data.Test, gather data.