[gmpi] Re: New Reqs 3.8 - Events

  • From: Chris Grigg <gmpi-public@xxxxxxxxxxxxxx>
  • To: gmpi@xxxxxxxxxxxxx
  • Date: Wed, 17 Dec 2003 13:26:58 -0800

> - Event routing. Do we want to require that the event mechanisms
 need to be transport-agnostic?  I.e. a message format that can pass
 over wires & radio waves etc., not just a function call.

Not sure what you mean by that. Go a bit deeper?

See UV's prior thoughts in re Ethernet, IP, UPD transport. Plus think event storage in timed file formats ala SMF. If events can have a standardized data representation, i.e. as messages, then they can ride all these transmission channels without worrying about ugly stuff like remote procedure call protocols and platform mismatches. The message might have two parts, a timestamp field (subject to conversion per the current channel's time model) plus an event payload field with target plug, target control, and value (data is not converted en route, just travels end-to-end like in IP).


Side question: For events originating in HW control surfaces, who adds the timestamp that the plug then uses? The host app? The GMPI graph manager? If the control surface box is running in sync with the host app, i.e. able to play stored control sequences, then timestamps could conceivably be added by the control surface itself (assuming that the host app is able to send the right setup info to the control surface). Lots of possibilities and questions here.


Another open issue is 'control gesture'.  I think it was Vincent who wanted
this.  He wanted the idea of providing a way to say "all these events are
one gesture".  I think it is mostly useful for things like 'Undo' features.
Obviously MIDI doesn't have any such concept, and automation doesn't need
it.  MouseDown / MouseUp map nicely to it, for GUI stuff.

Anyone recall what this was about? I'll troll the archives a bit.

Yes, this was nicely described, with Vincent's help IIRC, not too long ago.


-- Chris G.

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