Quiz II)

Overview of Today's Class [1/4]

Structural Patterns: Facade [2/4]

Patterns [3/4]

Other Patterns [4/4]

Announcements

Facade

Other patterns?

Class Review

Quiz (Last hour)

Name - Facade
Intent - Provide a unified interface to a set of interfaces in a subsystem. Facade defines a higher-level interface that makes the subsystem easier to use.
Problem -
- you want to provide a simple interface to a complex subsystem
- there are many dependencies between clients and the implementation classes of an abstraction
- you want to layer your subsystems
Solution -
Participants and Collaborators
- Facade
- subsystem classes (pattern independent)
Consequences
- shields clients from subsystem components
- promotes weak coupling between the subsystem and its clients
- doesn't prevent applications from using subsystem classes if they need to
Implementation
- Reducing client-subsystem coupling - you can make the Facade an abstract class and provide different concrete classes for different implementations of the subsystem. The client then doesn't need to know when you change subsystems.
GoF Reference (185)

Example files are here

		Purpose
		Creational	Structural	Behavioral
Scope	Class	Factory Method (107)	Adapter (class) (139)	Interpreter (243) Template Method (325)
Scope	Object	Abstract Factory (87) Builder (97) Prototype (117) Singleton (127)	Adapter (object) (139) Bridge (151) Composite (163) Decorator (175) Facade (185) Flyweight (195) Proxy (207)	Chain of Responsibility (223) Command (233) Iterator (257) Mediator (273) Memento (283) Observer (293) State (305) Strategy (315) Visitor (331)

Structural

Behavioral

Revised: 2002/06/03