[AG-TECH] Idea for creating "observer only" venues

Michael Daw michael.daw at manchester.ac.uk
Mon Oct 25 03:59:07 CDT 2004

We did a similar kind of thing for SC Global 2003 to create Observer venues.
Stephen Booth of EPCC did the writing of the code, which uses the UCL
libraries used for vic and rat.

You can get the code from here:

The relevant bit of the code is in common/examples/rtp_reflect.

Any specific questions beyond the simple, please direct straight to


> -----Original Message-----
> From: owner-ag-tech at mcs.anl.gov 
> [mailto:owner-ag-tech at mcs.anl.gov] On Behalf Of Frank Sweetser
> Sent: 25 October 2004 03:38
> To: Ivan R. Judson
> Cc: 'Frank Sweetser'; ag-tech at mcs.anl.gov
> Subject: Re: [AG-TECH] Idea for creating "observer only" venues
> On Sun, Oct 24, 2004 at 08:07:27PM -0500, Ivan R. Judson wrote:
> > 
> > 
> > Hey Frank,
> > 
> > In one respect I agree, the details are not completely 
> implemented, in 
> > another I disagree, since it's entirely conceivable that a 
> client can 
> > call the "enter" operation on the venue, but not the 
> "negotiate_capabilities"
> > call which would give them stream information.
> So you would let clients enter the venue, and view, say, 
> shared apps, but the media streams?  Neat!
> > We're currently considering how to support these calls in the next 
> > release and the ideas we have might support exactly what you're 
> > pointing out as a use case. We'll have to make sure.
> > 
> > In any case, if the venue can provide this functionality, it's much 
> > easier
> > :-)
> The real problem, as I see it, is that there's no way to push 
> out a "Let anyone recieve this multicast stream, but only 
> these addresses transmit to it" setting out to the router 
> infrastructure.
> Hm.  I have no idea how feasible this might be, but an 
> alternative might be to use asymetric encryption for the 
> multimedia streams.  Official participants would get both the 
> encryption and decryption keys, while the peanut gallery 
> would only get the decryption keys.  The traffic would still 
> go everywhere, but they wouldn't be able to wander in, leave 
> rat transmitting with a radio blaring, and then go to lunch 
> in the middle of an SCGlobal meeting.
> --
> Frank Sweetser fs at wpi.edu
> WPI Network Engineer
> GPG fingerprint = 6174 1257 129E 0D21 D8D4  E8A3 8E39 29E3 E2E8 8CEC

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