[compiz] Minutes of the Compiz Conference Call, 2009-01-21

[Guillaume Seguin]

Greetings everyone,

Here are the minutes of the very first Compiz Conference Call, which took place
today 2009-01-21. This was a combined IRC & phone meeting, huge thanks to Novell
and Michael Meeks for setting up the conference call.
The next Conference Call will take place on 2009-01-28.

Feel free to comment these minutes and ask questions to be sorted out during the
next meeting.

Conference Call 2009-01-21
==========================

Nomad
-----
http://en.opensuse.org/Nomad

What's Nomad
~~~~~~~~~~~
Compiz = one of the pieces needed to support Nomad
David created a proxy X server (xdmx) doing forwarding work to other X servers ;
xdmx is made to support all the new extensions, most importantly the Composite
extension, allowing the desktop that is connected to the proxy to be composited,
which is where Compiz becomes involved in Nomad

Nomad is better than current remote desktop solutions ; it allows to have a
fully composited desktop proxied to a toplevel window on another machine

Nomad & Compiz
~~~~~~~~~~~~~
See "nomad" branch of Compiz, which contains all the work David has been doing
to make this work

Infrastructure summary :
remote desktop, does no rendering <= instance of compiz on the remote side
<=> instance of compiz on the local side => local desktop
This infrastructure allows remote window management

What's needed : a nomad aware version of compiz running on the proxy
(i.e. Compiz is needed on both ends, there's some communication being done
between the instances of compiz to ensure everything works well ; there's more
than just remote desktop being done, there's also window management that can be
done locally => window management will always be responsive, no matter how well
performs the link between the local & remote sides)
It'll will eventualy support OpenGL and GLX, but doesn't yet

< onestone> david_r: why not start a second instance of compiz that handles
            the toplevel window as root, without such a big change
=> the current Nomad stuff is more efficient and uses less ressources, though
Dennis' proposal would be possible as well
There's basically no overhead in the remote desktop in the current Nomad
implementation

pro's for Nomad :
* improving the remote desktop experience by improving performance and
  smoothness, and enabling remotely enjoying the usual bling
* applications won't notice anything

Side-effect of Nomad branch : cleans up the rendering core, and generalises it
to hierarchies of windows, instead of a single level list.
(moves (glx) rendering out of core to plugins side) [~=> like in Compiz++]

Questions about Nomad:
~~~~~~~~~~~~~~~~~~~~~
Q: how should a missing compiz on the local side be handled ?
    [Lost-in-the-talk question]

Q: can a core interface be added for walking windows instead of having to
duplicate code across plugins (especially paint functions?)
    - code is shared, and existing plugins don't require substantial re-work

Q: surely this is only useful for remote desktop ?
    extremely useful even in the local case, when combined with virtualisation
    David heavily using it for this, backup, rollback, sync etc. all without
    loosing X / application state, or responsiveness.

Q. how does this relate to compiz-HEAD ?
    David would like to get this up-stream into HEAD, certain amount of
    audit work needed for each plugin.

Q. what protocols are supported ?
    Tweaked rdesktop, tunnelling X over RDP, and proxy can fall-back to
    rendering RDP commands instead [ for lame-ass Windows connectivity
    without compositing ]
    Free-software guys just use the compiz / X11 specific channel, and
    ~none of this is in compiz itself ?

Q: what about the changes here:
http://cgit.freedesktop.org/xorg/app/compiz/commit/?h=nomad-0.7.8&id=dbe3817cc78dbae883ae9d51f81ae62f5747789a
    Instead of having just one list of windows, we have a full hierarchy
    So each window, can contain another list of windows.
    Compiz has a lot of places, that used to walk the complete list of
    windows and do something for every one of them. Now we need to walk the
    complete tree.
    Lots of plugins keep working without applying affects to non-toplevel windows (?)
    [ these effects might not always work on remote desktop ].
    Fade plugin was updated to support Nomad - with this patch, and ~nothing
    more.

Q: what happens to object framework in case Nomad gets merged to head ?
    object framework, initially designed to help make Nomad easier to do
    those changes, affect way more plugins, than the final version we see now
    current design tries to break as few plugins as possible,
    that turned out far better than the huge re-architecting.
    even doing this, cleaned up a lot of things in the core.
    The object-framework work - lots of good stuff:
        + way too much work to get it merged
        + though lots of stuff in there that makes sense
        + at some stage, pull bits in from there,
        + but ~impossible to get it all in in one go.
        + do we really want to do that ?

About maintainership
--------------------
David doesn't have much time for Compiz general work, Nomads requires a lot of
time to get everything working perfect

Communication
-------------
There's a real problem, mailing lists aren't efficient there, lack of immediate
response.
=> a solution to setup a better communication is needed
Conference calls ? IRC meetings ?
Combined IRC + phone meetings seem to be the solution
Frequency : weekly
Timing : 14:00 GMT (seems to fit most)

Agenda for the next meeting
---------------------------
Next week : Management, directions, Compiz++, feedback on Nomad
Urgent topic : fixing the Compiz vs Compiz Fusion confusion [trackers, mls]
Possible topics : real merger, would solve the confusion

-----------------------------------------------------------------

Best regards,
Guillaume "iXce" Seguin
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