shea@csvax.cs.ukans.edu (Gary Shea) (09/22/90)
I have an x-terminal (ncd) which is used by different groups for different purposes. Each group uses a different machine as host. Unfortunately, users often leave minor programs (like a window manager, say) running after they logout, thus making life difficult for subsequent users who can't run their own wm. The obvious solution is xdm(1), but I am having a hard time seeing how the XDMCP supports my needs. What I want to do is run a sort of meta-xdm that puts a screen on the xterminal advertising a collection of hosts that would be happy to manage the display, then let the user select the desired host. At that point the standard indirect protocol would work fine, except that only one host would be in the list of acceptable hosts. Unfortunately, I can't see any way to do this within the protocol. Could someone explain what I'm missing, and (please!!) maybe even point me in the direction of some code? (I must be dreaming....) TIA -- Gary Shea Dept of Comp Sci shea@csvax.cs.ukans.edu Univ of Kansas garys@fire.cchem.berkeley.edu Lawrence, Kansas
rws@EXPO.LCS.MIT.EDU (Bob Scheifler) (09/22/90)
The obvious solution is xdm(1), but I am having a hard time seeing how the
XDMCP supports my needs. What I want to do is run a sort of meta-xdm that
puts a screen on the xterminal advertising a collection of hosts
that would be happy to manage the display, then let the user select
the desired host. At that point the standard indirect protocol would
work fine, except that only one host would be in the list of acceptable
hosts. Unfortunately, I can't see any way to do this within the protocol.
It is possible to do within the current XDMCP definition, although it
isn't perfect. If you put the "chooser" in the X terminal, then it's
pretty easy: the X terminal does an indirect or broadcast query, gets
a bunch of responses, displays them, and the user selects one. That
was pretty much the model we had in mind when XDMCP was designed.
Now, if you want to put the chooser in xdm (which in retrospect is
really a pretty good place to put it), then there is a bit of a problem,
as there is no direct way for xdm to do a "proxy" query on behalf of
the terminal. This can be hacked around by using a two-stage session,
with some state retained in xdm. Extending XDMCP with a proxy mechanism
would be another solution.
This is an area that we are actively working on for R5.mouse@LARRY.MCRCIM.MCGILL.EDU (09/23/90)
>> What I want to do is run a sort of meta-xdm that puts a screen on >> the xterminal advertising a collection of hosts that would be happy >> to manage the display, then let the user select the desired host. > It is possible to do within the current XDMCP definition, although it > isn't perfect. [...] Now, if you want to put the chooser in xdm > (which in retrospect is really a pretty good place to put it), then > there is a bit of a problem, as there is no direct way for xdm to do > a "proxy" query on behalf of the terminal. Depending on what sort of security mechanism you are using, you may be able to run xdm as one normally would in a one-xdm-host environment, but have the Xsession ask the user for a host to run on. This depends on several things, notably - more-or-less uniform user database across all machines involved - some way to make the chosen host able to connect to the server and run things like xhost which are restricted As rws says, not perfect, but it may be workable in the short term (eg, until R5 hits the streets). der Mouse old: mcgill-vision!mouse new: mouse@larry.mcrcim.mcgill.edu