[Discuss] FreeNx

[Alan W. Irwin]

On 2007-11-20 11:05-0800 Michael wrote:

> On Tue, 2007-11-20 at 10:49 -0800, Alan W. Irwin wrote:
>
>> On 2007-11-20 10:06-0800 Michael wrote:
>>
>>>
>>>
>>>> I think of FreeNX as a way to accelerate X communications over a low
>>>> bandwidth high-latency network.  In practice, though, I find it is not
>>>> needed for typical home LAN speeds of 100Mb/s.  For example, for our
>>>> thin-client configuration (X-terminal), we don't bother with it because
>>>> there is no noticable difference in X access speed locally or over our
>>>> 100Mb/s LAN.
>>>>
>>>> Let's call your boxes, box1, box2, and box3 ... // ...... simply be a matter of
>>>> hitting ctrl-alt-F7, ctrl-alt-F8, or ctr-alt-F9.  X networking support is
>>>> truly empowering!
>>>>
>>>> Alan
>>>
>>>
>>>    Am I understanding this correctly? Can I actually operate various
>>> headless systems via remote X sessions using FreeNX?
>>
>> Actually, that capability has been built right into X for decades so there
>> is no need to bother with FreeNX unless you are in a low-bandwidth
>> (internet) situation.  100Mb/s LAN's have plenty of speed so the FreeNX
>> complication is not required to run X applications (e.g., KDE) on any of the
>> boxes on your LAN with a monitor/keyboard mouse combination permanently
>> connected to just one of them.
>>
>> Alan
>
>
>    This is extremely interesting! The things I learn every day. What is
> this functionality called? I have never researched the x server at all,
> so I wouldn't have the first clue what to look for. I will start
> searching under "remote X sessions", but if it actually has a specific
> name, things will certainly go faster.

This method is used to enable so-called thin clients or X terminals which
run the X server (which controls the monitor, mouse, and keyboard) locally
and X applications (such as KDE or GNOME) remotely on a headless (but
extremely powerful) box.  Normally, only one headless box is involved when
dealing with thin clients, but there is no reason why you cannot have just
one fat client (with thin client capability) displaying X application
results from a number of headless boxes as well as X application results
from itself.

To give you some background, The city of Largo Florida has used the
thin-client approach where the ~500 city employees use thin clients to run
GNOME on one central server.  Dave Richards is in charge there, and you can
read his blog (http://davelargo.blogspot.com/) to see how it is going for
his second-generation 3D thin-client effort.

Another X-terminal general reference is ltsp.org.  But that is focussed
on all the details required for booting diskless thin clients, and since you
don't have to worry about diskless, you could get easily get lost in
those details.

Assuming you already have Linux running on all your headless boxes and your 
"headed" box, all that is really required is to set up xdm (X display
manager) on each headless box, and to run "X -query" on your headed box.
There is an X display manager entry for wikipedia at
http://en.wikipedia.org/wiki/X_display_manager which gives you some of the
background.  I mentioned xdm configuration details in
http://ladybug.vlug.org/pipermail/discuss/2007-November/023941.html.  Those
details are quite simple.  But you should also consult the xdm man page as
well since some of those details might be set up differently on your
particular distribution.

There are other X display managers than xdm (e.g., gdm, kdm, ldm), but to my
mind they all overcomplicate a simple task (to respond over the network to X
-query).  So I far prefer xdm over the others.

Alan
__________________________
Alan W. Irwin

Astronomical research affiliation with Department of Physics and Astronomy,
University of Victoria (astrowww.phys.uvic.ca).

Programming affiliations with the FreeEOS equation-of-state implementation
for stellar interiors (freeeos.sf.net); PLplot scientific plotting software
package (plplot.org); the libLASi project (unifont.org/lasi); the Loads of
Linux Links project (loll.sf.net); and the Linux Brochure Project
(lbproject.sf.net).
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Linux-powered Science
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