SYSTEM DEVELOPMENT METHODS

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IE 381 Management Information Systems

• SYSTEM DEVELOPMENT METHODS

???, ???, ??? Class Term Project 2005
Spring POSTECH
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Contents

• Systems Development Life Cycle (SDLC)
• Rapid Application Development (RAD)
• Prototyping

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Systems Development Life Cycle

• Definition
• The overall process of developing information
  systems through a multi step process from
  investigation of initial requirements through
  analysis, design, implementation and maintenance.
  
• 
  ltRussell Kay, Computer Worldgt
• Types of SDLC
• Waterfall, Fountain, Spiral
• Outputs from one step inputs to next
• Often referred to as the waterfall model
• (the
  oldest one - early 1970s)

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Waterfall Development Method
Systems Analysis
Systems Designs
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Phase 1 Investigation

• Initialization
• Management planning, Users needs opportunities
• Formal definition
• Objective, motivation, scope, boundaries,
  constraints, strategy
• Verifying a problem or deficiency really exists,
  or to pass judgment on the new requirement.
• Feasibilities studies
• Technical Feasibility is the availability of
  computing hardware and software to do a
  particular job. In many cases the managers
  concerns were well founded because the technology
  did not exist.
• Economic Feasibility is the ability of a system
  to pay for itself in monetary terms. Management
  does not want to spend a dollar unless it
  receives more than a dollar in return.
• Ex) The cost-benefit Analysis, Break-even
  Analysis, Payback Analysis, NPV.
• Operational Feasibility relates to the ability of
  the people working within a system to do their
  jobs in a prescribed manner.
• Ex) Ability of Users and Participants
  Attitudes of Users and Participants
• Organizational Feasibility. How well a proposed
  e-commerce system firs the companys plans for
  developing Web-based sales, marketing, and
  financial system.

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Phase 2 Analysis

• Analysis What a system should do to meet the
  needs of users.
• Determine requirements
• Study current system
• Structure requirements and eliminate redundancies
• Requirement Analysis
• Functional requirements
• Performance requirements
• Generate alternative designs
• Compare alternatives
• Recommend best alternative

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Phase 3 Design

• Design How the system will accomplish this
  objective.
• User interface Design
• Screen, Form, Report, and Dialog Design
• Data Design
• Data Element structure Design
• Process Design
• Program and Procedure Design

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Phase 4 Implementation

• Evaluating Hardware, Software, and Services
• Companies may use a scoring system of evaluation
  when there are several competing proposals for a
  hardware or software acquisition.
• Software Development or Modification
• Documentation
• Major mechanism of communication during
  development process
• Data Conversion
• Correcting incorrect data, filtering our unwanted
  data, consolidating data form several data
  warehouses.
• Testing
• Testing Debugging the Software
• Training

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Phase 4 Implementation

• Conversion

Parallel Strategy
Run old new systems for awhile to check
validity. Safe.
Pilot Strategy
Install in one part of organization at a time.
Learn and adapt
Phased Strategy
In large system change one function at a time
(e.g., order entry)
Plunge Strategy
Start using entire system. Can be dangerous if
errors exist.
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Phase 5 Maintenance

• Modification
• Modifying established system due to changes in
  the system for potential problems or necessary
  change.
• Correcting errors
• Feedback

ltMartin, Managing Information Technology p.395gt
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SDLC Pros and Cons

• Advantages
• Highly structured, systematic process
• Thorough requirements definition
• Clear milestone with business management
  sign-offs
• Disadvantages
• Does not account well for evolving requirements
  during project
• Time-consuming (and costly) process

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Motivation of RAD

• Limitation of SDLC
• Pressures for businesses to speed up
• Shorter development lifecycles
• Competition in changing global environment
• Why wait 3 years to develop systems likely to
  be obsolete upon completion?
• ? RAD methodology was born!

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Definition of RAD

• Rapid Application Design
• A system development methodology created to
  radically decrease the time needed to design and
  implement information systems
• ltJames Martin, RAD, CIRCAgt

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The 4 Essentials of RAD (1/2)

• Management
• Executives. Support for the RAD
• People
• Participation in JAD type
• Specialized team for RAD SWAT
• Skilled With Advanced Tools

• Joint application design (JAD)
• Group Decision Support System
• Users, Managers and Analysts work together for
  several days
• System requirements are reviewed
• Structured meetings

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The 4 Essentials of RAD (2/2)

• Methodologies
• RAD life cycle Users play key roles
• Tools
• Fourth-generation languages and CASE tools that
  facilitate prototyping and code generation

Computer-Aided Software Engineering (CASE) Any
software tool to transfer some of the systems
development workload from the human developer to
the computer by automating one or more steps of a
software development methodology
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RAD Life Cycle
Executives, managers, users determine
requirements JRP workshops to agree requirements,
overall planning
JAD session to develop basis design CASE tool is
used
Generate code End users validate design
Delivery of new system to users
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Definition of Prototyping

• The overall process of developing IS, which
  enables creation of system (or part of system)
  more quickly, then revising after users have
  tried it
• lt Martin, Managing Information Technology gt
• Selected features only some essential features
  included in prototype, more added later

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Prototyping Examples

• Graphic user interface usually needs several
  modification to meet the user requirements
• A completely operational prototype can be used as
  a pilot

Prototyping is similar to decide what shall
you be dressed in. This girl is the user. Various
designs of dresses are the prototypes. If the
user does not like the proposed one, developers
do modification until it meets the users
requirements.
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Prototyping Life Cycle
Prototype cycle

• OK!

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Prototyping Pros Cons

• Advantages
• Communications between the developer and user are
  improved
• The user plays a more active role in system
  development
• The information specialists and the user spend
  less time and effort in developing the system
• Implementation is much easier because the user
  knows what to expect
• Disadvantages
• End prototype often lacks security and control
  features
• May not undergo as rigorous testing
• Final documentation may be less complete
• More difficult to manage user expectations

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3 Types of System Development
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References

• OBrien, James, Introduction to Information
  Systems, McGraw-Hill
• Martin, James, Managing Information Technology
  ,Prentice Hall
• Martin, James, RAD, circa - Cooperative
  Intelligent Real-Time Control Architecture,1991
• Kenneth, at al, Management Information Systems,
  Prentice hall
• Raymond, at al, Management Information Systems,
  Prentice hall
• Russell, Kay, Quickstudy, http//www.computerwor
  ld.com

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Special Thanks To
MIS is one of the most appreciated
course by the graduates
POSMIS
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Questions?
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Pizza Party!