Software Design Concepts

• Principles
  • Algorithm
  • Abstraction
  • Abstract - Concrete
  • Logical - Physical
  • High Level - Low Level
  • Implementation
  • Data Representation - Mapping
  • Virtual Machine
  • Layering
  • Information Hiding
  • Encapsulation
  • Redundancy
  • Coupling (dependency)
    • Low (loose) Coupling - one module does not have not have to be concerned with the internal implementation of another module
    • High (tight) Coupling
  • Cohesion - a measure of how well the lines of source code within a module work together to provide a specific piece of functionality
  • Module - software entity that groups a set of subprograms and data structures
  • Interface
  • Abstract Data Types
• Structured
  • Data - Event
  • Process - Flow - Store
  • Data Dictionary
  • DFD - Data Flow Diagram
  • STD - State Transition Diagram
  • ERD - Entity Relationship Diagram
  • Structure Chart
  • Pseudo Code, Structured English
  • Essential Model - a model of what the system must do
    • Enviromental Model
      • Statement of purpose
      • Context Diagram
      • Event list
      • External flows and stores
    • Behavioural Model
    • Implementation Model
  • Design - a model of how the system works
    • Processor Model
    • Task Model
    • Program Implemenation Model
  • Top Down refinement/decomposition - requirements, specification, design, implementation
• Object Oriented
• Concurrency