Re: [Qemu-devel] Spice project is now open

[Mark McLoughlin]

On Fri, 2009-12-11 at 13:38 -0600, Anthony Liguori wrote:
> Mark McLoughlin wrote:
> > On Fri, 2009-12-11 at 13:04 -0600, Anthony Liguori wrote:
> >   
> >> But to introduce another protocol where a user has to make a choice to 
> >> use Spice over VNC, I think we need a really good justification for 
> >> that.  It's really about complexity.  A user shouldn't have to know 
> >> about Spice or VNC.  They shouldn't have to contemplate the trade-offs 
> >> of whether their management tool is aware or not.  It should Just Work. 
> >>     
> >
> > That's a good goal.
> >
> > If we add a new protocol, we could achieve the same thing by allowing
> > qemu support both VNC and Spice at runtime. Then you just need a client
> > like virt-viewer that can handle both protocols, and old VNC clients
> > will continue to be able to connect to newer qemu.
> >   
> 
> Supporting them at the same time could be potentially challenging.  You 
> would need to render Spice locally in qemu in order to expose it via vnc.
> 
> Another nasty bit is that two protocols mean two different sets of 
> authentication mechanisms.  Does Spice support SASL based 
> authentication?  Could it make sense to essentially tunnel Spice through 
> vnc in order to reuse the existing authentication infrastructure?

I don't doubt there are challenges.

I think your requirement that old clients work with new servers and new
clients work with old servers is a good one. Maybe extending VNC is the
best way to get there, but it should be recognized there is another way
of achieving the same thing if Spice does require a new protocol.

The underlying goal is getting lost in the "Spice can't be a VNC
extension" discussion :-)

Cheers,
Mark.