General questions/conjectures about DBUS etc.

[Chris Green]

On Sat, Mar 24, 2012 at 01:02:48PM +0900, Andrzej wrote:
> On 03/24/2012 06:29 AM, Chris Green wrote:
> >
> >(running Calibre in particular)
> 
> Which Calibre? (just curious)
> 
The one that manages eBooks.

> >I've noticed with thunar and calibre that running them on my laptop but
> >using my desktop machine as the display it feels as if they're sort of
> >"half and half", some of what they're doing relates to the laptop on
> >which they're running but some relates to my desktop machine where they
> >are displaying.
> 
> It's not just thunar. It is a general problem and Xfce is not in the
> position to change this trend. Which makes the rest of this email
> off-topic, but well...
> 
Yes, I guessed as much, but I wanted to be sure I wasn't seeing
behaviour due to some misconfiguration on my part.


> This behavior is exactly what you would expect when mixing DBUS,
> audio and X together. X only forwards your display, keyboard and
> mouse. Audio and DBUS messages go through completely different
> channels, which, unless you set them up explicitly, usually end up
> pointing to the remote (X client) machine.
> 
> There are also other problems, modern applications usually use some
> X extensions that require shared memory (render, composite etc),
> perform poorly or look ugly over network, NFS is getting rare these
> days (what's the point of having network transparency if each app
> sees different data?) etc. In short: network transparency only works
> with legacy X applications in a legacy X environment (with NFS/NIS,
> ethernet etc.).
> 
> You can try to hack things a bit. For DBUS you can play with
> DBUS_SESSION_BUS_ADDRESS variable (first you will have to enable
> networking in your local DBUS session daemon). To tell the truth,
> I've never tried it. I found that accessing a remote machine over
> VNC/RDP gives much better results - there is no network transparency
> but at least it is made obvious (not half-remote, half-local as in
> X). Often the performance is even better than X because these
> protocols are less sensitive to network latency and the bandwidth
> has improved a lot. Not to say about detach/reattach capability,
> which is a must today.
> 
> >Does this sound possible/sensible?  Are modern GUI apps tested in a
> >multi-machine X environment?
> 
> Worse, it is *designed* not to work well in such environments. The
> disparity between network latency and performance of local systems
> became so large that people started pushing local-only solutions.
> Can't really blame them for that - X was good in '90 when graphics
> performance was limited by drawing operations, network latency was
> smaller than now, network and memory bandwidth narrow, and network
> installations we centralized. None of this is true now.
> 
> </offtopic>
> 
Thanks for the comments, how am I going to manage headless servers now? 
OK, I can do most of what I need to do from the command line but as
things advance the command line interface tends to get neglected so one
is almost forced to use a GUI to do things.

-- 
Chris Green