Re: [Jack-Devel] ladish + jack autoconnect

"Tim E. Real" <[hidden]> writes:

> To help new users and as a stepping stone to a better configuration system, 
>  at startup I auto-fill our midi ports with found Jack midi devices now.
> By that I mean I scan for Jack midi ports and create matching client ports
>  and then automatically connect them together.
> Then everything is ready to go, the user can immediately start creating midi 
>  tracks and doesn't necessarily have to open our midi configuration dlg.
> Thus as viewed in say qjackctl, we have matching client ports and 
>  connections for every outside port found.
>  
> Not fond of auto-doing anything, it's behaviour can change as our 
>  configuration system evolves, or be removed (and may very well be). 
> But previously it was a rather clumsy affair for our users to set up devices.
>
> So anyway I actually wanted to have the app /continuously/ watch for new ports
>  and auto connect them as well, instead of just at startup or on-demand.
> I didn't, because it seems a bad idea. 
> It could lead to infinite recursive auto-connecting. Right?
>
> Say two apps employ this auto-connecting technique.
> Then they are both constantly watching for each others' ports.
> As soon as the second app starts the first app creates matching ports,
>  then the second app sees these new ports and creates matching ones,
>  then the first one sees those ports and creates matching ones, and so on.
>
> I'm wondering if even the one-time auto-connect at startup is still a bad 
>  idea. It still kinda WIP, maybe make it more optional (click-to-auto-fill). 
> (There sure are a lot of ports created!)
> With this talk of auto-connect and session managers I would like to ask if 
>  this one-time auto-connect at startup might also interfere with session 
>  managers like LASH or LADISH, or even say Jack Session? (We only have LASH.) 
> Maybe I should determine whether it is in fact a session, and bypass
>  the automatic port creation and auto-connecting at startup...

It will interfere badly with ladish if ladish rooms are in use. Please
make your app to not autoconnect when it detects that it is started by
the ladish daemon. Qtractor already implementes such check. The check
inspects the LADISH_APP_NAME environment variable. The environment
variables that ladishd sets upon starting app are documented here:

http://ladish.org/wiki/envvars

I'll leave jack-session detection to be described by whom worships it.

AFAIK LASH library initialization success is a sign of LASH server
availability.

The bad(or good) news here is that at some point ladish will allow self
connects. For this to work properly jack clients/ports participating in
given virtual graph should be separated from those participating in
other virtual graphs. Separated at JACK API level. This is actually a
good reason to not ban (in political sense) autoconnects at app level
but to restrict them in the jack server, when user setup actually
requires it.

-- 
Nedko Arnaudov <GnuPG KeyID: 5D1B58ED>

1325988047.14741_0.ltw:2,Sa <87k4530x9j.fsf at arnaudov dot name>