| TransportController | Base interface to controlling a media transport. |
| TransportMediator | Helper for implementing a media transport control (with play, pause, skip, and other media actions). |
| TransportPerformer | Implemented by the playback side of the media system, to respond to requests to perform actions and to retrieve its current state. |
| TransportStateListener | A listener for playback changes that can be registered with
TransportController. |
