[AG-TECH] Collaborative VNC

Brian Corrie bcorrie at sfu.ca
Thu Jul 21 12:44:04 CDT 2005

Hello all,

Hmmm, this does look interesting!

Julia Mullen wrote:

> Hi Natalia -
> This sounds great!  Have you resolved the issue of slow VNC when you have
> multiple sites?  In addition, I have seen a number of issues arising
> when a presenting site wants to share software or images that require
> high resolution, such as biomedical applications.  Do you have any
> experience with this?

Our experience is that VNC does not scale well, as Julia suggests. Of 
course, it is not terribly interactive as well.

For high quality visualization applications, you might want to look at 
our Shared Visualization Server shared app. Of course you need an SGI to 
do this, which doesn't help a large number of people perhaps, but 
theoretically something similar could be done with other platforms.

The qualities about the visualization server software are that it can do 
very high quality imagery (true pixels) at interactive rates if you have 
the network. This is due to optimization at the server (both hardware 
and software) and client side. It also supports a range of compression 
schemes that are also optimized for interactivity. Thus you can scale 
back the network requirements if necessary, with the goal of maintaining 
interactivity (which is the key with collaborative visualization).

> and the final question that users are forever asking me - what are the
> security risks of collaborative-vnc?  I assume they are the same as
> for vnc, is that correct?

It is inherently risky since you give up control of your workstation. 
VNC security is not great in terms of how it handles passwords either. 
Also, it means you have to open up other ports to the outside world, 
which is also adds risk. VNC uses a known port, so you can set it up so 
that the port is different (I think when you start the server). This 
won't help you if someone does a port scan, but at least the obvious 
port will not be vulnerable...



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