prototyping_j m carey

8/8/2019 Prototyping_J M Carey

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Prototyping: alternative

systems development

methodology by J M Carey

Presented by Cynthia

JohnsonFebruary 7, 2007 EEL 6883


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What is Prototyping?

Prototyping is the process of quickly

building a model of the final software

system, which is used primarily as acommunication tool to assess and

meet the information needs of the

user? J M Carey


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Why use prototyping?

Helps user clarify their needs

Less ambiguous than traditionalnarrative function specification

Improves team communication. Apicture is worth a 1000 words

Less emphasis on time consuming

documentationGenerally faster than traditionaldevelopment


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Why prototype?

The prototype provides a vehicle forsystems engineers to better understand theenvironment and the requirements problembeing addressed.

A prototype is a demonstration of what'sactually feasible with existing technology,and where the technical weak spots stillexist.

A prototype lets the developer meet earlierschedules for the production version.

A prototype allows for early customerinteraction.


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Prototyping Environments

Two major types of prototyping

environments mentioned.

Automated development environmentsPrototyping toolkits a collection of

unintegrated tools.


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Fourth and Fifth Generation

Software Languages

Often abbreviated 4GL, fourth-generation languages areprogramming languages which are

closer to human language thanprevious languages.

Most of todays 4GLs are database

languages. One example is FINDALL RECORDS WHERE NAME IS"SMITH"


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The generations of computer

languages

1st GenerationMachine Language

2nd Generation

Assembly Language3rd GenerationC, C++, FORTRAN, Java, Pascal, Ada

4th GenerationSQL, RPG-II

5th GenerationUsed for artificial intelligence and neuralnetworks primarily researchers


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Successful 4GL Languages

Database Query

SQL, Progress 4GL, Informix

Report GeneratorsBuildProfessional, PostScript

Data Manipulation and Reporting

Clarion, GraphTalkScreen Painters, GUI Developers

FourGen, Visual Basic


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Types of Prototyping

Type I Iterative

Type II - Throwaway


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Type I - Iterative

Uses the Prototype as the final

system after a series of iterative

upgrades

Generally uses a 4GL tool for

development


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Type II - Throwaway

Prototype is developed in 4GL or

toolkit

Final product based on prototype builtin 3GL language.


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Advantages of prototyping

Faster development time

Easier for end-users to learn to use

More end-user involvementEnhances user/analysts

communication

Requirements are easier todetermine.


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Disadvantages of prototyping

Undue user expectations

Inconsistencies between prototype

and final productFinal system inefficiencies

Lack of attention to good human

factors practice.Inattention to proper design and

analysis.


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When to prototype

A good prototyping candidate is

Dynamic

Transaction processing basedContains extensive user dialogs

Is small

Is well defined

Is online

is the business


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When not to prototype

A system with the following attributes

is not a good candidate

Is stableIs decision-support based

Is ill-defined

Makes little use of user dialogs

Is real-time

Has lots of number crunching


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Methodology

Following good methodology is key to

successful prototyping

Four phases of prototypedevelopment

Determine what to prototype

Build the prototype

Test the prototype

Use the prototype as a model


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Incorporating Human Factors

Prototyping does nothing to ensureuse of good human factors practices.

The issue of user friendly or usabilityhas become a huge determinant ofsystem success.

A system that works perfectly may be

rejected if difficult to useNote that this is not an issue thatapplies just to prototypes.


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Some good guidelines

Know your user

Use selection not entry

Make the system behave predictablyMake the system unobtrusive

Change displays as little as possible

Minimize keystrokes and mouse use

Use meaningful error messages

Allow for undo


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Case Study- NJ DMV

Price Waterhouse contracted to buildNew Jerseys DMV primaryinformation system.

They chose a new (at the time)4GLcalled Ideal from Applied DataResearch to develop the system

When delivered, the response timewas so slow that the backlog requiredthousands of hours of overtime


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What went wrong?

Ideal was new and untested.

Little time was spent training staff in

its useThe contract imposed bigger

penalties for late system than a non

performing one

They ignored consultants warnings

that Ideal was not the right tool.


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How did they fix it?

By converting 58 of 800 modules to

COBOL, system performance was

made acceptable.

Those 58 modules performed 85% of

the systems work.


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Case Study: Town and Country

Credit Line

Banking card system improvement

Hired consultants to help them

choose IEF (Information EngineeringFacility) from Texas Instruments

Used Iterative prototyping and

delivered a successful system


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What went right?

Tool was 5 years more advanced

than Ideal

They did a more extensive study ofavailable tools before choosing

Learned from others mistakes


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Summary

Prototyping is made possible by the

availability of4GLs and soon 5GL

Not all systems are good candidatesfor prototyping

For those that are, prototyping can

reduce development time and cost

Prototyping does not ensure good

human factors


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My opinion

Im not a big fan of type II prototyping.

Anything that gets thrown away seems

wasteful and end product may not match

prototype.Iterative prototyping is good for working out

incompletely defined user interfaces

Customer is usually happier when they

have up front involvement in final product.


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Additional References

http://www.webopedia.com/TERM/F/fourth_generation_language.html

http://en.wikipedia.org/wiki/4GL

Importance of SoftwarePrototyping by Larry Bernstein -Have Laptop - Will Travel,

http://www.dacs.dtic.mil/awareness/newsletters/technews2-1/prototyping.html

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