Facade and Singleton

Every dluid module has Facade and Singleton class. ~Facade class in Dluid is interface for each module. In brief, The ~Facade is responsible for communication between the module. Basically upper module can access to any class of under modules. Therefore, upper modules may communicate directly with singleton in under modules. But, access using the Facade is recommended.

By comparison with Spring Framework, Facade in dluid is controller and singleton is being used as ApplicationContext.