How are ros_control controllers and hardware_interfaces used?

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Dear all,

The doc for ros_control says ros_control provides controller interfaces. Does that mean ros_control abstracts real controllers?

• I noticed ros_control also provides software controllers? I guess these are mostly used for simulation or for cheap control in real life, is that right?
• Now, are the controllers interfaces (i.e. controllers abstractions) used both in case of real hardware drivers and in case of ros_control emulated controllers?

Thanks,

Antoine.

PS: please note that I have read all the doc I could find for ros_control (both in the wiki or on github).