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The Prototyping Approach. Techniques for prototype application. Type I (Procedure) High volume Low transaction cost Well structured Measurable Process & efficiency Data Clerical. Type II (Goal) Low volume High trans. value Poorly structured Hard to measure Goal & effectiveness

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the prototyping approach

The Prototyping Approach

Techniques for prototype application

types of information systems sprague watson dss for management prentice hall 1996
Type I (Procedure)

High volume

Low transaction cost

Well structured

Measurable

Process & efficiency

Data

Clerical

Type II (Goal)

Low volume

High trans. value

Poorly structured

Hard to measure

Goal & effectiveness

Concepts

Mgrs, professionals

Types of Information Systems Sprague & Watson, DSS for Management, Prentice Hall, 1996
is development approaches
IS Development Approaches
  • Systems Development Life Cycle
  • Information Center (DSS)
  • Object and Component
type i large systems
Type ILarge Systems
  • Intercommunications among applications
  • Formal methodologies
  • CASE technologies
  • Purchased products
  • Outsourcing
type i sdlc
Type ISDLC
  • Type I systems
  • Large and Costly
  • Cost justified
  • Formal stages of evaluation
  • Stages carefully reviewed and formally approved
  • Data, Process, Communications
type ii information center dss
Type IIInformation Center (DSS)
  • Type II systems
  • Relatively small and inexpensive
  • Value justified
  • Prototyping and evolutionary design
  • Data, Dialog, Model
prototyping
Prototyping

“It is easier to tell what you don’t like about an existing system than to describe what you would like in an imaginary one”

A.M. Jenkins, 1983

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

Choice
the prototyping process
The Prototyping Process

Identify

Initial

Requirements

Use and

Evaluate

Develop

System

Iterate

Document and Install

prototyping life cycle
Prototyping Life Cycle
  • Determine suitability for prototyping
  • Identify basic needs
  • Develop working model
  • Demonstrate and solicit refinements
  • Revise and redemonstrate
  • Clean up and document
assumptions
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
use prototyping if
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
do not use prototyping if
Do Not Use Prototyping If
  • Don’t understand tools
  • Data not well managed
  • Software not well managed
  • Professional staff not available
  • Technology response not adequate
  • User not willing to invest time
factors favoring prototyping
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
factors favoring prototyping16
Factors Favoring Prototyping
  • Problem:

imprecise specifications,

poorly defined communications,

interactive model needed

Why not use prototyping

roles
Roles
  • 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)
requirements for successful prototyping user
Requirements for Successful Prototyping: User
  • Initiate the process
  • Seeks IS assistance
  • Competent in business area
  • Willing to spend time with system
requirements for successful prototyping builder
Requirements for Successful Prototyping: Builder
  • Assigned to Prototyping
  • Competent with tools
  • Knows organizational data resources
requirements for successful prototyping technology
Requirements for Successful Prototyping: Technology
  • Roles identified
  • 4GL Tools established
  • Data is managed
  • Technology response adequate
builders added value professional design
Builders Added Value(Professional Design)
  • Date and time stamps
  • Control totals
  • Audit trails
  • Common interface feel
  • Additional functions
  • Testing
prototyping principles
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

prototyping principles23
Add

Modify

Display

Delete

Locate

Browse

Activate

Copy

Connect

Stop

Prototyping Principles

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

prototyping principles24
Prototyping Principles

3. Most editing derives from a small set of models.

  • Tunnel edits
  • Cross field edits
  • Cross record edits
prototyping principles25
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
prototyping principles26
Audit trails

Control totals

Menu and command modes

Help facility

Standard screen formats

Date/time stamping

Ergonomics

Prototyping Principles

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

prototyping tactics
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
prototyping tactics28
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
project management
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
additional implementation requirements
AdditionalImplementation Requirements
  • Operational documentation and procedures
  • Data size and operational impact analysis
  • Test plan
  • Training procedures
tactic
Tactic
  • Evolution
  • Throwaway
  • Life Cycle component
references
References
  • Bernard H. Boar, Application Prototyping, Wiley, 1984.
  • Ralph Sprague & Eric Carlson, Building Effective Decision Support Systems, Prentice Hall, 1984.