System Analysis and Design Notes

1.0 Introduction to System Analysis and Design

  • Introduction to information systems, systems analysis and design concepts, and systems development methods.
  • Covers project plan preparation and project management.

1.1 Discuss Information System

  • Information:
    • Data transformed into valuable output.
    • Characteristics:
      • Accurate and timely.
      • Specific and organized for a purpose.
      • Presented within a context providing meaning and relevance.
      • Leads to increased understanding and decreased uncertainty.
  • Information System:
    • Combination of technology, people, and data.
    • Supports business functions (order processing, inventory control, HR, accounting, etc.).
  • Information System Components:
    • Hardware:
      • Physical layer of the IS.
      • Examples: servers, workstations, networks, telecommunications equipment, fiber-optic cables, mobile devices, scanners, digital capture devices, infrastructure.
    • Software:
      • Information processing instructions.
      • System software (e.g., operating system).
      • Application software (programs for specific computer uses by end users).
    • Data:
      • Raw material of information systems and databases.
      • Forms: alphanumeric, text, image, audio.
    • Processes:
      • Tasks and business functions performed by users, managers, and IT staff.
      • Building blocks representing day-to-day business operations.
    • People:
      • Stakeholders with interest in the IS.
      • Management group responsible for the system.
      • Users (end users) inside and outside the company (accountants, salespersons, engineers, clerks, customers, managers, etc.).
      • IT staff: systems analysts, programmers, network administrators.

Types of Information Systems

  • Traditional Labels (In the Past):
    • Administrative staff used office systems.
    • Operational people used operational systems.
    • Middle managers used decision support systems.
    • Top managers used executive information systems.
  • Today: All employees use office productivity systems.
  • Types of Information Systems:
    • Enterprise Computing Systems (ECS):
      • Support company-wide operations and data management.
      • Examples: Wal-Mart’s inventory, Boeing’s production control, Hilton Hotels’ reservation system.
      • Objectives:
        • Integrate primary functions.
        • Improve efficiency and reduce costs.
        • Help managers make key decisions.
        • Improve data security and reliability.
    • User Productivity Systems (UPS):
      • Technology to improve employee productivity.
      • Examples: email, voicemail, video and web conferencing, word processing, calendars, database management, spreadsheets, desktop publishing, presentation graphics, company intranets, mobile computing systems, groupware.
      • Groupware: enables data sharing and collaboration.
    • Business Support Systems (BSS):
      • Job-related information support to users.
      • Analyze transactional data.
      • Generate information for business process management.
      • Provide information for decision making.
      • Decision support through computer models and variables.
      • Management Information Systems (MIS) for managers.
    • Knowledge Management Systems (KMS):
      • Use a knowledge base to find information using keywords.
      • Use inference rules (logical rules for data patterns and relationships).
    • Transaction Processing System (TPS):
      • Operational-level systems.
      • Operated by shop floor workers or front line staff.
      • Support management of operations.
      • Data from automated tracking of low-level activities and transactions.
      • Examples: Payroll, order processing, reservation, stock control, payment systems.
      • Roles:
        • Produce information for other systems.
        • Cross internal and external boundaries.
        • Used by operational personnel and supervisory levels.
        • Efficiency oriented.

1.2 System Development Approach

  • System Development Methods:
    • Structured Analysis
    • Object-Oriented Analysis
    • Agile Methods

System Development Life Cycle (SDLC)

  • Basic Activities:
    • Planning
    • Analysis
    • Design
    • Development
    • Testing
    • Implementation
    • Maintenance
  • System Development Life Cycle Activities:
    • Planning:
      • Begins with a systems request to IT describing problems or desired changes.
      • Perform preliminary investigation to evaluate IT business opportunity or problem.
      • Deliverable: Preliminary Investigation Report.
    • Analysis:
      • Build a logical model of the new system.
      • Requirements modeling to document what the new system must do.
      • Fact-finding (interviews, surveys, document review, observation, sampling).
      • Build business models, data and process models, and object models.
      • Deliverable: System requirements document.
    • Design:
      • Create a physical model to satisfy system requirements.
      • Design user interface and identify outputs, inputs, and processes.
      • Determine application architecture for transforming the logical design into program modules and code.
      • Deliverable: System design specification.
    • Development:
      • New system construction.
      • Programs are written and documented.
    • Testing:
      • Ensure workability; bring pieces together for testing.
      • Check for errors, bugs, and interoperability.
      • Verification and validation used.
    • Implementation:
      • Deliver a completely functioning and documented information system.
      • Convert data, train users, transition to the new system.
      • System is ready for use.
      • Systems evaluation: determine proper operation and cost-benefit analysis.
    • Maintenance:
      • Corrections, additions, and moves are made.
      • Correct errors and adapt to environmental changes (e.g., new tax rates).
      • Enhancements provide new features and benefits.
      • Objective: Maximize return on IT investment.

Types of Life Cycle Models

  • Waterfall Model
  • Spiral Model
  • Iterative and Incremental Development
  • Agile Model
  • Prototyping Model
  • Rapid Application Development (RAD)
  • Joint Application Development (JAD)
  • Models Descriptions:
    • Waterfall Model:
      • First model for software development.
      • Structured analysis System Development method.
      • Linear-sequential life cycle model.
      • Phases: plan, analyze, design, implement, support.
      • Each phase completed before the next begins; no overlapping.
    • Agile Model:
      • Develop system incrementally.
      • Build prototypes and adjust to user requirements.
      • Continuous feedback.
      • Series of iterations based on feedback.
      • Scrum is a popular Agile model with 2-4 week sprints.
    • Spiral Model:
      • Intense team-based effort.
      • Reiterate earlier stages.
      • Breaks development into cycles/iterations that add functionality.
      • Cycles are designed, built, and tested.
      • Series of short waterfall cycles.
    • Iterative and Incremental Development:
      • Simple implementation of a small software set.
      • Iteratively enhance versions until complete.
      • Specify and implement part of the software then review for further requirements.
      • New software version at the end of each iteration.
    • Prototyping Model:
      • Build software application prototypes.
      • Display product functionality.
      • Understand customer requirements early.
      • Get feedback from customer.
    • Rapid Application Development (RAD):
      • Team-based technique to speed up IS development.
      • Produces a functioning IS.
      • Users involved every step.
      • Includes all SDLC phases.
    • Joint Application Development (JAD):
      • Involve client in application design and development.
      • Collaborative workshops (JAD sessions).
      • Structured group process for determining requirements.
      • Advantages:
        • Allows key user participation.
        • Results in accurate requirements statement.
        • Better understanding of goals.
        • Stronger commitment to success.
      • Disadvantage:
        • More expensive and cumbersome.