[Box-Admins] Re: understanding remote image viewing options

Levente Uzonyi leves at elte.hu
Mon Nov 11 17:53:45 UTC 2013

On Mon, 11 Nov 2013, Chris Muller wrote:

> Levente, I'm glad you posted about xpra, because I've been meaning to
> try it out as well as Squeak's RFB.
> I would like to ask you (and others here of course!) about options for
> remote image operation, and try to understand the differences between
> them.  By my understanding, we have 1) VNC, 2) Squeak RFB and 3) xpra.

We use Squeak's RFB and xpra at the same time. xpra is less responsive, so 
we use it only if RFB doesn't work for some reason (e.g.: pressing Alt+. 
is likely to interrupt the RFB process, which can be fixed using xpra).

> (VNC desktop) Sharing entire desktops on my LAN is handy for accessing
> multiple running images on another machine all at once.  The downside
> is that it's single-user, since anyone else trying to use the desktop
> will be disrupted.
> (VNC display :1) Sharing an alternate display by starting xtightvnc on
> the server, starting Squeak vm with the -display :1 argument, one can
> then use remote viewing tools like Remmina to reconnect to that
> running Squeak image.
> (xpra) This is for sharing a single program at a time.  You can start

You can run multiple programs on the server using the same display.

> an image on a particular display.  This seems similar to above except
> it can run across ssh rather than having to share a VNC password..?
> One thing I was wondering was whether the Squeak vm could be started
> with the -display arg like above or only that strange way you said:
> $DISPLAY=:100 squeak -vm-sound-null squeaksource.image..?

The main advantages over VNC are:
- all windows will appear on your desktop, not in a separate window
- supports shared sessions (only the newer versions)
- lightweight

> (Squeak RFB) From Ian, my understanding is this uses the image itself
> to send its graphics over the network for remote op.  Might slow down
> the image but the advantage here could be if you're on a machine on
> which you cannot install and/or run remote viewing software..?

Squeak's RFB is the most responsive among these three options, because it 
knows exactly what has changed on the screen. If the remote server is not 
too far away from you, then this will feel like you're working with an 
image on your machine. It requires way less resources than you'd expect.

We use the following hack to make Squeak display the mouse pointer:
ActiveHand userInitials: ' ' andPicture: nil.


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