Prototyping

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Prototyping

• Keng Siau
• Department of Management
• University of Nebraska-Lincoln

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Obstacles in Systems Analysis and Design

• Users do not know what they want
• unfamiliar with information technology
• unfamiliar with the objectives of the projects
• Users keep changing their minds
• Analyst-User communication
• different background and training
• SDLC takes a long time

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Prototyping

• A technique for quickly gathering specific
  information about users information requirements
• Useful in seeking
• user reactions
• suggestions
• innovations
• revision plans

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Types of Prototypes

• Patched-up prototype
• Nonoperational prototype
• First-of-a-series prototype
• Selected features prototype

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Patched-Up Prototype

• Constructing a system that works but is patched
  up or patched together
• Problems
• programs are written rapidly with the objective
  of being workable
• Has the necessary features but is inefficient
• retrieval and storage of information may be
  inefficient

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Nonoperational Prototype

• A nonworking scale model for the purposes of
  testing certain aspects of the design
• Example
• prototyping the input and output of the system
  only
• Problem
• it is a nonworking model

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First-of-a-Series Prototype

• Creating a first full-scale model of a system
• known as a pilot
• installing the system in a branch to work through
  the problems before full-scale installation
• Problem
• compared to other prototyping approaches, this
  approach is quite costly and time-consuming

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Selected Features Prototype

• Building an operational model that includes some,
  but not all, of the features that the final
  system will have
• Prototypes are part of the actual system
• System is built in modules

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Guidelines for Prototyping

• Work in manageable modules
• Build the prototype rapidly
• Modify the prototype in successive iterations
• Stress the user interface

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Prototyping-- An Alternative to SDLC

• Advantages
• shortens the time between information
  requirements phase and delivery of a workable
  system
• overcome some problems of accurately identifying
  users information requirements
• users can see what is possible and what is not

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Prototyping-- An Alternative to SDLC

• Disadvantages
• prematurely shaping a system
• producing a system inadequate for overall
  organizational needs

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Prototyping-- An Alternative to SDLC

• Remedy
• use prototyping as a part of SDLC
• use prototyping to get users information
  requirements

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Systems Suitable for Prototyping

• Design Experience
• only a few times
• Environment
• uncertain and unstable
• Decision Making
• unstructured or semi-structured

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Advantages of Prototyping

• Change the system early in its development
• Scrap undesirable systems
• Design a system for users needs and expectations

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Disadvantages of Prototyping

• Manage the project
• danger of overtaking other phases in SDLC
• Adopt an incomplete system as complete
• Documentation might be incomplete

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Users Role in Prototyping

• Experiment with the prototype
• Give open reactions to the prototype
• Suggest changes to the prototype

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Rapid Application Development (RAD)

• RAD, or rapid application development, is an
  approach to systems development that includes a
  method of development as well as software tools

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RAD Phases

• The three broad phases to RAD are
• Requirements planning
• RAD design workshop
• Implementation

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Requirements Planning Phase

• Users and analysts meet to identify objectives of
  the application or system
• Oriented toward solving business problems

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RAD Design Workshop

• Design and refine phase
• Use group decision support systems to help users
  agree on designs
• Programmers and analysts can build and show
  visual representations of the designs and
  workflow to users
• Users respond to actual working prototypes
• Analysts refine designed modules based on user
  responses

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Implementation Phase

• As the systems are built and refined, the new
  systems or partial systems are tested and
  introduced to the organization
• When creating new systems, there is no need to
  run old systems in parallel

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Martin Approach to RAD
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RAD and the SDLC

• RAD tools are used to generate screens and
  exhibit the overall flow of the application
• Users approve the design and sign off on the
  visual model
• Implementation is less stressful because users
  helped to design the business aspects of the
  system

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When to Use RAD

• RAD is used when
• The team includes programmers and analysts who
  are experienced with it
• There are pressing reasons for speeding up
  application development
• The project involves a novel ecommerce
  application and needs quick results
• Users are sophisticated and highly engaged with
  the goals of the company

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Disadvantages of RAD

• May try and hurry the project too much
• Loosely documented

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Agile Modeling

• Agile modeling is similar to XP
• In addition to the values of communication,
  simplicity, feedback and courage, a fifth value,
  humility, is added
• Agile modelers do not insist that they are always
  right

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Agile Modeling (Continued)

• Agile modeling process is
• Listen to user stories
• Draw a logical workflow model
• Create new user stories based on the workflow
• Develop some prototypes
• Use feedback from the prototypes and logical
  workflow to create physical model