Types of Design

Business Systems

Examples

• Internet sites.
• Inventory management.
• Games.
• Payroll.

Life Cycle Models

• Agile.
• Prototyping.

Planning

• Plan in increments during development.
• Testing and quality planning as needed.
• Informal change control (at will).

Requirements

• Informal specification (description, use cases).

Design

• Design and coding combined (agile).

Implementation

• Pair programming.
• Informal code check-in.
• As-needed code reviews.

Testing

• Little or no testing group.

Mission critical systems

Examples

• Embedded software.
• Software Tools.
• Web Services; ie payment and booking.

Life Cycle Models

• Staged delivery.
  • Reduce risks by installing in parts.
• Spiral development.
  • A combination of prototyping and Waterfall.

Planning

• Some initial planning.
• Basic testing.
• Formal change control (document changes).

Requirements

• As needed requirements reviews to ensure correctness.

Design

• Design the archetecture (high level) before coding.
• No strict design format.

Implementation

• Pair programming.
• Informal code check-in.
• As-needed code reviews.

Testing

• Identified testing group.

Life critical systems

Examples

• Avionics.
• Embedded software in cars or machines.
• Medical devices.
• Operating systems.
• Military systems.

Life Cycle Models

• Life critical.
• Staged delivery.
• Spiral development.

Planning

• Extensive initial planning and test plan; may be legally required.
• Rigorous change control; change planned before you make it.

Requirements

• Formal requirement inspections and specifications.

Design

• Archetecture designed before coding.
• Formal archetechture inspections.
• Formal detailed design.
• Formal design inspections.

Implementation

• Pair Programming.
• Formal code check in (plan change before implenting).
• Formal code reviews.

Testing

• Testing group separate from the developers.