Re: [Jack-Devel] How to run multiple jackdbus

Thomas DEBESSE <[hidden]> writes:

> I'm trying to run multiple jackdbus…

You are entering terra incognita... :)

> I'm writing an app and I want to use jackd with another server name
> than "default" to let the user to have is own jackd!
> The idea is to launch a jackd and do some connections between elements
> without polluting the user's jackd nor his patchbay, and perhaps
> provide a virtual interface between the two jackd.
>
> I can rename jackd easily with cli jackd and jackdbus, I know how to
> run multiple legacy jackd, but I don't know how to run multiple
> jackdbus.
> I'm writing an app and I like how it's cool to configure and manage
> jackd using jack dbus interfaces, but if I start and configure jackd
> using dbus and renaming it to "other" (instead of "default"), I'm not
> running another dbus, I'm renaming the default jackd ! This is not I
> want. If the user try to run jackdbus, he will use my jackd!
>
> Any Idea ?

The current jackdbus D-Bus presentation was designed for single server
scenario. For multiserver scenario, the plan was to have one D-Bus
object per server controller and eventually an object+interface for
managing these objects (add new server, remove it, rename it). How
people are actually using multiserver scenario was never clear to
me. Multiple cards? Multiple users? Testing setups?

There are several problematic areas:
 * one jackdbus instance per session bus
 * per-user jack server settings that are autosaved
 * session vs user

"session vs user" is actually issue at dbus level. AFAIK it is not yet
solved. I clearly see different use of per-user bus daemon and
per-session bus daemon. Right now they are merged. If you treat it as
session bus, you want to access it from different sessions. If you treat
it as user bus then you may want multiple services per user (multiple
cards, test setups).

"per-user jack server settings that are autosaved" is issue only if you
want to use multiple jack server intances per user. It is clear that each
server must have its own settings persisted in ~/.config/jack/. It is
not clear whether all jack servers must run within same jackdbus process,
or there must be one jackdbus process per server, or something in
between.

"one jackdbus instance per session bus" is problem only if you treat
session bus as user bus. It should be possible to run multiple session
bus daemons for same user with each jackdbus daemon attaching to
different dbus session bus. I can imagine only one functionality that
could cause problem - the X11 server storage for session bus address. If
it indeed is a problem, I think you can build dbus without this
functionality (but your "desktop/login" setup could break, depends on
how it is made).

A related issue is that server name in jackdbus engine settings is
useless and some users get into trap to set it. In context of
multiserver setups, the server name is actually key/id for settings of
that server. In context of single user setups, the server name only
causes confusion. So this engine setting should be removed from the
D-Bus presentation of the engine settings and maybe even from the
control API.

-- 
Nedko Arnaudov <GnuPG KeyID: 5D1B58ED>

1352296379.24934_0.ltw:2,a <87sj8led5b.fsf at arnaudov dot name>