Prototyping: alternative systems development methodology by J M Carey

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Prototyping alternative systems development
methodology by J M Carey

• Presented by Cynthia Johnson
• February 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 a communication tool to assess
  and meet the information needs of the user? J
  M Carey

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What is prototyping?

• Prototyping is the use of approximately 30 of
  the ultimate staff to build one or two working
  versions of various aspects of a system. It is
  not production code but it may eventually become
  pre-production code or it may be completely
  discarded. In the prototyping effort, we are not
  concerned with the maintainability of the code
  nor are we concerned with formally documenting
  it. Larry Bernstein

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Why use prototyping?

• Helps user clarify their needs
• Less ambiguous than traditional narrative
  function specification
• Improves team communication. A picture is worth
  a 1000 words
• Less emphasis on time consuming documentation
• Generally faster than traditional development

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Why prototype?

• The prototype provides a vehicle for systems
  engineers to better understand the environment
  and the requirements problem being addressed.
• A prototype is a demonstration of what's actually
  feasible with existing technology, and where the
  technical weak spots still exist.
• A prototype lets the developer meet earlier
  schedules for the production version.
• A prototype allows for early customer
  interaction.

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Prototyping Environments

• Two major types of prototyping environments
  mentioned.
• Automated development environments
• Prototyping toolkits a collection of
  unintegrated tools.

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Fourth and Fifth Generation Software Languages

• Often abbreviated 4GL, fourth-generation
  languages are programming languages which are
  closer to human language than previous languages.
  
• Most of todays 4GLs are database languages. One
  example is FIND ALL RECORDS WHERE NAME IS "SMITH"

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The generations of computer languages

• 1st Generation
• Machine Language
• 2nd Generation
• Assembly Language
• 3rd Generation
• C, C, FORTRAN, Java, Pascal, Ada
• 4th Generation
• SQL, RPG-II
• 5th Generation
• Used for artificial intelligence and neural
  networks primarily researchers

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Successful 4GL Languages

• Database Query
• SQL, Progress 4GL, Informix
• Report Generators
• BuildProfessional, PostScript
• Data Manipulation and Reporting
• Clarion, GraphTalk
• Screen 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 built in 3GL
  language.

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Advantages of prototyping

• Faster development time
• Easier for end-users to learn to use
• More end-user involvement
• Enhances user/analysts communication
• Requirements are easier to determine.

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Disadvantages of prototyping

• Undue user expectations
• Inconsistencies between prototype and final
  product
• Final 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 based
• Contains 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 stable
• Is 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 prototype development
• 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 ensure use of good
  human factors practices.
• The issue of user friendly or usability has
  become a huge determinant of system success.
• A system that works perfectly may be rejected if
  difficult to use
• Note that this is not an issue that applies just
  to prototypes.

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Some good guidelines

• Know your user
• Use selection not entry
• Make the system behave predictably
• Make 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 build New Jerseys
  DMV primary information system.
• They chose a new (at the time)4GL called Ideal
  from Applied Data Research to develop the system
• When delivered, the response time was so slow
  that the backlog required thousands of hours of
  overtime

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What went wrong?

• Ideal was new and untested.
• Little time was spent training staff in its use
• The 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 Engineering Facility) 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 of available
  tools before choosing
• Learned from others mistakes

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Summary

• Prototyping is made possible by the availability
  of 4GLs and soon 5GL
• Not all systems are good candidates for
  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 Software Prototyping by Larry
  Bernstein - Have Laptop - Will Travel,
  http//www.dacs.dtic.mil/awareness/newsletters/tec
  hnews2-1/prototyping.html