An interface declaration is basically the same as a
component declaration but is meant to be
shared between several components. Although any object can be defined in an
interface, it will typically only declare service prototypes and ports that
are to be provided or used by components.
In addition to regular component properties, an interface can also define the following properties:
A list of interfaces that are imported as-is into the current one. All objects from the extended interfaces appear as if they had been defined in the extending interface.