DBUS Support

I'm writing MPRIS dbus support for SMPlayer. I've gotten two of the four interfaces up, and i have two questions, one simple, one not so much.
Simple Question:
Does it make sense to implement Tracklist?
I don't think it does, since smplayer doesn't really have a media library.
Other Question:
How are commands passed back and forth within the application?
IE: how do i from my quit, next, or pause methods, send a command to smplayer to quit, next, or pause?
I don't need a complete answer, maybe just a good place to start?
Thanks
Kevin
Simple Question:
Does it make sense to implement Tracklist?
I don't think it does, since smplayer doesn't really have a media library.
Other Question:
How are commands passed back and forth within the application?
IE: how do i from my quit, next, or pause methods, send a command to smplayer to quit, next, or pause?
I don't need a complete answer, maybe just a good place to start?
Thanks
Kevin