1. Extending Interface Based Design

2. Logical vs. Physical Design
Logical Design
Essential vs. Inessential Coupling
Interface as Type
Design Patterns
Physical Design
Assemblies
Versioning

3. Goals of Physical Design
Easier to test and change smaller units
Faster unit tests
Easier parallel development
Easier change management

4. Assembly Partitioning Concepts
Look for application fault lines
Treat Interfaces as fundamental types
Design Patterns indicate application partitions

5. Interfaces as Fundamental Types
Interfaces are behavior, not implementation
Treat as fundamental types
Place in separate assemblies
Put implementation in separate assemblies

6. Patterns Drive Partitions
Code that implements the pattern
Code that uses the pattern
Code the pattern isolates
Indicate possible assembly partitioning

7. Example: Factory Pattern
Application
CustomerManagerFactory
CustomerManager

8. Assemblies As Components
Independent evolution
Versioning
Testing
Goal is partitioning
Reuse is possibly emergent

9. Design For Testability
Test smaller units of functionality Faster unit tests Minimize test dependencies Partitioning for testability

10. Physical Design Challenges
Assembly Management Reduced Encapsulation Performance Problems Probability of Change

11. Summary Partition based on: Fundamental Types Patterns
Test Dependencies