[ohm] OHM vs. PPM

Marcel Holtmann marcel at holtmann.org
Fri May 2 05:08:37 PDT 2008

Hi Rob,

> >>>> OHM needs some work before its usable on a desktop system, mainly in 
> >>>> that it should become a session daemon rather than a system daemon - 
> >>>> connecting up to X from the system is not ideal.
> >>> why? Leave it as system daemon and have an "agent" running in the X
> >>> session that OHM can refer requests to. You might wanna check out on how
> >>> BlueZ does it with PIN requests and mode change confirmations.
> >> These two sentences are too short for getting a complete overview about
> >> the BlueZ way of doing these things, but this sounds like what we already
> >> had with the powersave daemon and kpowersave (the time kpowersave was only
> >> a client for powersaved).
> > 
> > this needs a lot more explaining, but the beauty with the solution that
> > BLueZ uses is that you don't need any extra well known names for the
> > applet running in the user session. Even the actual object path is fully
> > dynamic and then indeed allows to have multiple or stacked agents.
> > 
> > It works like this:
> > 
> > 	client creates object
> > 	client call RegisterAgent(object) on the server
> > 
> > After that the server knows the unique name of the agent/client since it
> > comes via the message. It also knows the object path of the clients
> > objects. The only common factor is the interface definition to be used
> > on that specific object. The server can also monitor the
> > NameOwnerChanged signal to see if the client dies unexpected.
> > 
> > For all requests that need user interaction, the server can now call
> > into the interface from the agent.
> > 
> > This gives the perfect system level versus user session separation
> > without playing any dirty tricks or having static bus names or object
> > paths.
> That sounds like a very nice pattern, I'll keep it in mind.

check the BlueZ source code or have me to explain it to you in detail
when we run into each other. It is a little bit tricky in the beginning,
but so beautiful once you have done it :)



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