Façade vs. Mediator

Question

I\'ve been researching the difference between these two patterns.

I understand that facade encapsulates access to a sub system and mediator encapsulates the interac

Answer 1

Both impose some kind of policy on another group of objects. Facade imposes the policy from above, and Mediator imposes the policy from below. The use of Facade is visible and constraining, while the use of Mediator is invisible and enabling.

The Facade pattern is used when you want to provide a simple and specific interface to a group of objects that has a complex and general interface.

The Mediator pattern also imposes policy. However, whereas Facade imposed its policy in a visible and constraining way, Mediator imposes its policies in a hidden and unconstrained way.

Agile Software Development, Principles, Patterns, and Practices Robert C. Martin.