Explaining Facade

Projects can sometimes turn out to be very complex and big, making them difficult to design and organize. To solve this, a great solution is to break a system into subsystems (divide and conquer) and make them less complex and better organized.

The Facade pattern creates a higher-level interface to hide a complexity of a set of interfaces in a subsystem. This pattern reduces the complexity and coupling, minimizing communication and dependencies between subsystems. In the following diagram, you can see the structure of Facade and how it is designed:

In the preceding diagram, we can see the Facade pattern encapsulating all of the calls to subsystems and hiding these calls from the client. The system has one interface, Facade, and the client calls this interface in order to call subsystems. Thus, clients does not call the subsystems directly. With this solution, the client doesn't need to know about the subsystem and its complexity.

This pattern is often used in projects and systems that have high complexity and need to be broken down into subsystems.