CHAPTER 14 INFORMATION SYSTEMS DEVELOPMENT

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CHAPTER 14INFORMATION SYSTEMS DEVELOPMENT
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Initiation System Development

• Problems with existing systems
• Desire to exploit new opportunity
• Increase competition
• Organizational growth
• Changes in the market or external environment
• Changes in organizational structure
• New laws and regulations

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Information Systems Planning
IS Planning Process
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Information System Strategic Plan

• Reflects the mission of IS department
• Must correspond to the organizations strategic
  plan
• Must provide efficient information architecture
  for long term
• Allocates information technology resources in
  optimal way

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Four-Stage Model of IS Planning

• Strategic IS planning
• Information requirements analysis
• Resources allocation analysis
• Project planning

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Strategic Planning
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Organization Requirements Analysis

• Assessment
• Information architecture
• Current information needs
• Projected information needs
• Assemble master development plan
• IS project definition
• Project ranking
• Development schedule

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Resources Allocation Planning

• Trend identification
• Hardware plan
• Software plan
• Communications networks plan
• Facilities plan
• Financial plan

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Project Planning

• Project evaluation
• Task definition
• Cost estimates
• Time estimates
• Checkpoints
• Completion dates

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Operational Plan

• Mission of the function
• IS environment
• Objectives of the IS function
• Constraints on the IS function
• Long-term systems need
• Short-range plan

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Systems Development Life Cycle (SDLC)

• SDLC structured framework
• Major steps
• Development activities
• After development activities
• Waterfall Approach - no loops back onto previous
  steps

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An Eight-Stage Systems Development Life Cycle
(SDLC)
(1) Systems Investigation
(2) Systems Analysis
(3) Systems Design
(4) Programming
(5) Testing
(6) Implementation
(7) Operation
(8) Maintenance
Go Back to a previous Stage or Stop
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Systems Investigation (Step 1)

• Determine the exact problem
• Feasibility Study
• technical feasibility
• economic feasibility
• Time value of money
• Net present value
• Return on investment
• Breakeven point
• behavioral feasibility

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Systems Analysis (Step 2)

• Assembling the participants for system analysis
• Collecting appropriate data and requirements
• Analyzing the data and requirements
• Formulation new system requirements and project
  priorities

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Data Analysis

• Data modeling
• ERD
• Activity modeling
• Data flow diagram
• Data flow lines
• Process symbols
• Entity symbols
• Data storage
• Application flow chart

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Entity-Relationship Diagram
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Data Flow Diagram
Schedule Data
Schedule course
Academic department
Offered Courses
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Systems Design (Step 3)

• System outputs, inputs, and user interfaces
• Hardware, telecommunications, and procedures
• Software, databases
• Personnel
• How these components are integrated
• Two-step process
• Logical systems design what the system will do
• Physical systems design how the system
  components are accomplished

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Programming (Step 4)

• The translation of the design specifications into
  computer code
• Select programming language
• Structured programming
• Entire program consists of a number of modules
• Each module implements one particular task
• Each module has exactly one input and one output
• GO TO statement is not allowed

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Structured programming techniques

• Sequence structure
• If-then-else structure
• Loop structure
• Procedure

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Testing (step 5)

• Debugging
• Eliminating of syntax errors
• Eliminating logical errors
• Tests planning
• All branches in the code must be tested

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Implementation (Step 6)

• Parallel conversion
• Direct conversion
• Pilot conversion
• Phased conversion

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Operation and Maintenance

• Operation (Step 7)
• Maintenance (Step 8)
• debugging the program
• updating the system to accommodate changes in
  business conditions
• add new functionality to the system

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Alternatives to Conventional SDLC

• Prototyping
• Joint application development
• Rapid application development
• Object-oriented development
• End-user application development

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Prototyping

• Prototyping obtain only a general idea of user
  requirements
• Advantages
• speeds up the development approach
• gives the users the opportunity to clarify their
  information requirements
• useful in the development of decision support
  systems and executive information systems
• Disadvantages
• replaces the systematic analysis and design
  stages of the SDLC - quality may be sacrificed
• can result in an excess of iterations

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Joint Application Design (JAD)

• JAD is a group-based method for collecting user
  requirements and creating system designs
• Advantages
• saves time
• greater support for, and acceptance of new
  systems
• produces higher quality systems
• easier implementation
• lower training costs
• Disadvantages
• very difficult to get all users to JAD meetings
• all the problems that may be caused by any group
  process

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Rapid Application Development (RAD)

• Combine JAD, prototyping, iterative development,
  and integrated CASE tools, to rapidly produce a
  high-quality system
• Spiral development
• Each iteration contains a combination of SDLC
  steps
• Each iteration refines the system
• Each iteration produces a system that can be used
• Features are added according to users priorities,
  requirements, function reuse, implementation risk

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Advantages of Spiral Development

• High parallelism
• High user involvement
• Produce better system
• Users satisfaction
• Gradual resources commitment
• Frequent product delivery

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RAD Packages

• GUI development environment
• Libraries of standard objects
• Code generators
• Integrated development environment to create
  computer codes

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Integrated Computer-Aided Software Engineering
(ICASE) Tools

• ICASE Tools automate many of the tasks in the
  SDLC
• Upper CASE
• lower CASE
• integrated CASE
• CASE tools components
• Diagramming tools
• Analysis tools
• Repository tool
• Code generators

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Advantages of RAD

• speeds the development process
• reduces development costs
• can create applications that are easier to
  maintain and modify
• Disadvantages
• may result in systems with limited functionality
  and adaptability for change
• Not suitable for sophisticated calculations

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Object-Oriented Development

• OOD considers real-world systems as sets of
  interacting entities, which have attributes
• An entity is described as an object
• Entitys attributes are described as objects
  properties
• Methods (or operations) are used to change
  objects properties (or data values)
• Object class incorporates similar objects
• Each object is considered as an instance of
  object class
• Objects interact with each other by means of
  messages

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End-User Development

• Increasing the power of desktop hardware
• Reducing hardware cost
• Increasing software capability
• Increasing computer-literate population
• Small and ad hoc application
• Advantages
• Users get control over all stages of SDLC
• Save time and money on application development

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Disadvantages of End-User Development

• Applications are simple
• More advanced hardware and software are needed
• Leads to a large number of isolated applications
• Attracts time from main business duties
• Have limited area of application

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External Acquisition of Software

• Outsourcing
• Factors considered during make-or-buy decision
• on-time
• on-budget
• full functionality
• user acceptance
• favorable costs-to-benefits ratio
• low maintenance
• scalability
• integration with other systems
• minimal negative cross-impacts
• reusability