Re: Persistant Sessions

[Michael Rogers <banthafodder connectfree co uk>]

Sean McElroy wrote:
> 
> Not meaning to troll or anything, but I'm curious: I read that WinXP will
> allow users to 'log off' while preserving their tasks and desktop state as
> if they had not made any change to their session, and upon logging on again,
> they return to their previous desktop.

I think it could be done, albeit in a very hacky way:

When you logged out, the X server would fork off a child process that
would inherit all its sockets and shared memory (thus keeping your apps
alive). All your windows would be unmapped, so your apps wouldn't waste
too much time drawing to a nonexistent screen! Both processes would
relinquish control of the graphics card, and the original X server
process would terminate. The new process would carry on running in the
background (X daemon), and would either write its PID to a file in your
home directory or listen on a particular socket or whatever.

Oh, maybe it would have to wake up periodically, to stop the clients
blocking if they insisted on talking to the server when they didn't have
any windows mapped. I'm not sure.

When you logged in, the display manager would look for an X daemon
belonging to you. If it found one, it would relinquish the graphics card
and then re-awaken the X daemon. (I think I read a sci-fi novel by that
name once.) The X daemon would claim the graphics card and start
behaving like a normal X server again.

But I've used machines that had half a dozen of someone else's zombie
Netscape processes running in the background, and trust me, you don't
want this.  ;-)


Michael