deploy the daemon

[Havoc Pennington]

Simon Burton wrote:
> I am rather confused about this..
> 
> On my local machine I have a dbus app (two programs that use dbus for IPC),
> and everything works fine using:
> 
> dbus_bus_get(DBUS_BUS_SESSION, err_addr)
> 
> and I find these running processes:
> $ ps ax|grep dbus
>  5406 ?        Ss     0:00 /usr/bin/dbus-daemon --system
>  6673 ?        Ss     0:00 /usr/bin/ssh-agent /usr/bin/dbus-launch --exit-with-session x-session-manager
>  6676 ?        S      0:00 /usr/bin/dbus-launch --exit-with-session x-session-manager
>  6677 ?        Ss     0:10 dbus-daemon --fork --print-pid 8 --print-address 6 --session
> 
> 
> On the target (FC5 x86-64) machine there is no X running, but I see:
> 
> $ ps ax|grep dbus
>  2109 ?        Ss     0:00 dbus-daemon --system
> 
> Can I use this daemon for my app ?

This is the system bus. The --session one is the session bus. The docs 
make various attempts to explain this, some may be clearer to you than 
others. There's an explanation in here:
http://www.freedesktop.org/wiki/IntroductionToDBus
and in here:
http://dbus.freedesktop.org/doc/dbus-tutorial.html
and a third attempt:
http://doc.trolltech.com/4.2/intro-to-dbus.html

In short, there is a session bus for every X login session, and a single 
system bus for the whole machine shared among all users.

> I don't seem to be able to
> request a name (dbus_bus_request_name) when I use
> dbus_bus_get(DBUS_BUS_SYSTEM, err_addr).

The system bus is locked down by security policies, these can be found 
in /etc/dbus-1/system.d and there is documentation in "man dbus-daemon" 
To use the system bus you need to install a security policy to allow 
your application through in an appropriate way.

Which bus to use depends on what you're doing. You can also skip using a 
bus and just have two apps talk to each other, by running your own 
"DBusServer" in one of the apps.

Havoc