RFP: Keyboard Configuration Registry over dbus

["Sergey Udaltsov" <sergey udaltsov gmail com>]

Hello people

I already sent request to d-d-l and g-d-l but, since there was no
reply, I had a quick chat with Sebastian on IRC and would like to ask
here.

So, the problem is how to keep and provide the XKB configuration
registry. It is a large XML file which should not be parsed more than
once per GNOME session (or may be even per system?).

For a moment, every application which needs it - loads and parses it.
For example, one copy is loaded by gnome-keyboard-indicator applet,
one copy loaded by gnome-keyboard-properties. Not nice, is it? Since
there is a request to add layout indication to gnome-screensaver,
there would be a third copy of the same stuff loaded. Which I think is
a bad idea.

So, the good idea is to provide this information over dbus from one
"server" application. There can be 3 approaches:

1. DBUS interface to g-s-d.
 Good:
   - No extra processes
 Bad:
   - g-s-d would start slower, take more RAM

2. Separate daemon (capplets/keyboard/gnome-xkb-config-registry)
starting with the session
 Good:
   - g-s-d is not affected
 Bad:
   - Separate maintenance unit.
   - Separate process requires even more RAM than #1, session startup
still getting slower.

3. Separate daemon starting on demand (using dbus activation)
 Good:
   - g-s-d is not affected
   - RAM is allocated only when necessary
   - Session startup is not affected unless gnome-keyboard-indicator
applet is loaded.
 Bad:
   - Separate maintenance unit.
   - Separate process requires even more RAM than #1, session startup
still getting slower.

I would like to know your opinion on the subject (personally I think
#3 is most viable solution)

Thanks,

Sergey