Use cases

The most common reason to use the façade pattern is to provide a single, simple entry point to a complex system. By introducing a façade, the client code can use a system by simply calling a single method/function. At the same time, the internal system does not lose any functionality; it just encapsulates it.

Not exposing the internal functionality of a system to the client code gives us an extra benefit: we can introduce changes to the system, but the client code remains unaware of and unaffected by the changes. No modifications are required to the client code.

The façade is also useful if you have more than one layer in your system. You can introduce one façade entry point per layer, and let all layers communicate with each other through their façades. This, in turn, promotes loose coupling and keeps the layers as independent as possible.

With that, we are now ready to try our hand at an actual implementation example in the next section...