[ILUG] Sun and the sunray thingy

[Caolan McNamara]

I was up at Sun yesterday and had a gawk at their sunray thingy, very nice I 
have to say. One big server elsewhere and each local machine is just a monitor
and a sunray box, no local harddrives or fan or moving parts, so completely
silent. about 10x10 inches and 2 deep. Couple of usb ports hanging out of the 
back of the box, monitor keyboard and power cables, all resources are remote. 
Each users gets a card and they can use that to bypassing logging in and out, 
stick in the card and "twap" up comes your session exactly as it was when you 
pulled out the card, pull out the card and wander over to another machine and 
stick it in, and again"twap" up it comes. Very sweet. 

I originally thought that the card was just sending a session close downrequest
to all the apps, and that they were saving their state, you know the thing you
can do with gnome and kde and other apps which save their location on screen,
and optionally save their state so that they can start up again and put 
themselves in as close a state as they were when they were shut down, but on
closer examination this wasnt the case at all, i got suspicious when I noted
that an ordinary spread of apps were managing to remember their entire state,
down to what menu entry you highlighted, etc etc. In fact the session remains 
running all the time (if you just put in and pull out the card), so for instance
if you have netscape downloading a file, twap the card out and come back 
tomorrow, stick in the card into a completely different machine if you so
desire, and ta-da the session has remained open for the duration and netscape 
is still running. Very cool. 

There was a catch though, each server machine hosts about 20-30 clients, and
if you twap your card into a client attached to a different server then you
dont get the original desktop which is running happily away on the first server,
and utterly disconnected from the second server.

What I'd like to figure out is what trick is sun doing here, does each user
get a virtual XServer on the main server (xvfb sort of thing), which is 
then piped down to the sunray which sticks it onto the monitor. Or is there
some magic trick where all the X apps are reparented from one display (the
virtual one) to another (the sunray one). Like what the hell ? Anyone in Sun
gonna let me in on the mechanics here, maybe its a lot easier than ive been
thinking.

Anyways I thought it was pretty cool, Id also like to know what sort of stuff
is actually inside the sunray box, some standard sparc processor ? etc etc,
could linux every run on such equipment etc, or is the box basically dumb which
is what I imagine. Who controls any usb devices that get plugged into the box ?
and so on...

C.

Real Life: Caolan McNamara           *  Doing: MSc in HCI
Work: Caolan.McNamara at ul.ie          *  Phone: +353-86-8790257
URL: http://www.csn.ul.ie/~caolan    *  Sig: an oblique strategy
Don't be frightened of cliches