Why do we Model?

  • Provide structure for problem solving
  • Experiment to explore multiple solutions
  • Furnish abstractions to manage complexity
  • Reduce time-to-market for business problem solutions
  • Decrease development costs
  • Manage the risk of mistakes

System Development Life Cycle (SDLC)

  • Waterfall effect
    • Each phase flows into the next
    • Plan – Analyze – Design – Implement – Support

System Planning

  • Identify and prioritize proposed system
  • Define scope and boundary of problem

sdlc-1

System Analysis

  • Build a logical model of the system
  • Analyze current problems, causes and effects
  • Define business requirements
  • Inputs: Facts and requirements
  • Outputs: Business requirements document

sdlc-2

System Design

  • Design the solution that meets business requirements:
    • Create a physical model of the system.
    • User interfaces
    • Internal and external controls
    • Security
  • Inputs: Business requirements document
  • Outputs: Technical design document

sdlc-3

System Implementation

  • Create new improved information system
  • Input – technical design document
  • Output – system delivered, end user training and documentation
  • Develop conversion strategy
    • Parallel, direct cutover, phased, pilot

sdlc-4

System Operation and Support

  • Review implementation, refine design, implement improvements
  • Maintenance of system for remainder of useful life

sdlc-5

Systems Development Guidelines

  • Follow your overall development plan
  • Ensure that the users are involved from the beginning so that you get “buy in” and you fully understand their system requirements
  • Listen, listen and listen!!
  • Identify your major milestones for project review and assessment.
  • Establish interim checkpoints between the major milestones to ensure that your project remains on schedule.
  • Keep flexible with the parameters of your plan
  • Provide reliable cost and benefit information.

System Development Tools/Techniques

1. Modeling (DFD, ERD, UML)

  • Graphical representation
  • Business model
  • Object model
  • Data model
  • Network model
  • Process model

2. Prototyping

  • Purpose to test system concepts before implementation
    • Feasibility
    • Requirements
    • Design (Behavioral)
    • Implementation (Production)
  • Benefits
  • Disadvantages

3. CASE Tools (Computer Aided Systems Engineering)

  • Powerful software to assist systems analysts to develop and maintain information systems
  • Benefits
    • Easier to build software
    • Increased IT productivity
    • Methodologies that work

4. Other Tools/Techniques

  • Structured Analysis
  • Object Oriented Analysis
  • Joint Application Development (JAD)

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