Prototyping Environment

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Prototyping Environment

• Requirements for rapid application development

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Prototyping

• It is easier to tell what you dont like about
  an existing system than to describe what you
  would like in an imaginary one
• A.M. Jenkins, 1983

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The Prototyping Process
Identify Initial Requirements
Use and Evaluate
Develop System
Iterate
Document and Install
4
Roles

• Approver Approves payment and accepts final
  product
• User Responsible for business solutions
• Intermediary Run system for user
• Builder Write code for application
• Technical Supports the development
  Support tools
• Toolsmith Build basic tool modules (often work
  for software houses)

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Requirements for Successful Prototyping User

• Initiate the process
• Seeks IS assistance
• Competent in business area
• Willing to spend time with system

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Requirements for Successful Prototyping Builder

• Assigned to Prototyping
• Competent with tools
• Knows organizational data resources

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Requirements for Successful Prototyping
Technology

• Roles identified
• 4GL Tools established
• Data is managed
• Technology response adequate

8
Use Prototyping If

• Life cycle too slow
• Scope of project manageable
• 30 screens
• Small team 1-2 users/designers
• 50 attributes
• User not sure of specifications
• User satisfaction very important
• Reporting or DSS
• Irregular or infrequent use

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Do Not Use Prototyping If

• Dont understand tools
• Data not well managed
• Software not well managed
• Professional staff not available
• Technology response not adequate
• User not willing to invest time

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Assumptions

• All requirements cannot be specified
• Quick build tools are available
• Communications gap between builders and users
• Active models are required
• Rigorous approaches are appropriate once
  requirements are known
• Iteration is valuable

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Choice

• Life Cycle
• Prespecification possible
• Changes expensive
• Good project communication
• Static model OK
• Rigorous approach useful
• Iteration unacceptable

• Prototype
• Prespecification difficult
• Quick tools work
• Communications gap
• Animated model needed
• Rigor after requirements
• Iteration accepted

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Life Cycle

• Determine suitability for prototyping
• Identify basic needs
• Develop working model
• Demonstrate and solicit refinements
• Revise and redemonstrate
• Clean up and document

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Factors Favoring Prototyping

• Structure interactive, on-line (OLAP)
• Logic structured but not algorithmic
• DSS applications are often data-report types
• User competent and active participant
• Time Constraint not a crash project
• Management willing to work with method
• Size not overly large or complex

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Factors Favoring Prototyping

• Problem
• imprecise specifications,
• poorly defined communications,
• interactive model needed
• Why not use prototyping

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Builders Added Value(Professional Design)

• Date and time stamps
• Control totals
• Audit trails
• Common interface feel
• Additional functions
• Testing

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Prototyping Principles

• 1. Most applications arise from a small set of
  basic systems
• 1. Batch edit/update 7. On-line application
• 2. Batch reporting interface
• 3. Batch data update 8. On-line report
• 4. Batch interface
• 5. On-line update/query
• 6. On-line ad hoc query

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Prototyping Principles
2. Most systems use a common set of
data processing functions

• Browse
• Activate
• Copy
• Connect
• Stop

• Add
• Modify
• Display
• Delete
• Locate

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Prototyping Principles

• 3. Most editing derives from a small set of
  models.
• Tunnel edits
• Cross field edits
• Cross record edits

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Prototyping Principles

• 4. Most reports are based on a four step
  process.
• Select data from the database
• Sort by specification
• Format and edit for printing
• Print

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Prototyping Principles
5. There are a standard set of value added
design structures that should be added

• Standard screen formats
• Date/time stamping
• Ergonomics

• Audit trails
• Control totals
• Menu and command modes
• Help facility

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Prototyping Tactics

• Normalize data to 3NF
• Use component engineering
• Use existing components
• Assemble from existing parts
• Reuse pieces
• Create pieces so that they can be reused
• Cut and paste
• Keep a set of examples

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Prototyping Tactics

• Use active data dictionaries
• Automate documentation
• Keep teams small
• Integrated software workbench tools
• Specify objectives not procedures
• Provide end-user report writing tools
• Use professional prototypers
• Have systems developers work with prototypers

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Project Management

• Initial Model 2-6 weeks
• Must be fast enough to maintain interest
• Revisions immediate - 2 weeks
• Chargeback use charges to avoid frivolous
  changes
• Approval determine the group who approves
  iterations
• Sign off formal acceptance

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AdditionalImplementation Requirements

• Operational documentation and procedures
• Data size and operational impact analysis
• Test plan
• Training procedures

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Tactic

• Evolution
• Throwaway
• Life Cycle component

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References

• Bernard H. Boar, Application Prototyping, Wiley,
  1984.
• Ralph Sprague Eric Carlson, Building Effective
  Decision Support Systems, Prentice Hall, 1984.