Subject: [AVT] Application sharing - a first protocol draft

From: Henning Schulzrinne <[email-masked]>
Date: Thu, 13 Jan 2005 13:50:56 -0500

We have put together an initial draft on how to do applicationg sharing, 
at the pixel level. For reasons discussed also in our earlier 
requirements document 
(http://www.ietf.org/internet-drafts/draft-schulzrinne-mmusic-sharing-00.txt), 
we believe that this is closely related to remote access to applications 
and that timing information is relevant. Thus, the initial draft 
primarily defines RTP payload types. Until the draft appears in the 
archives, you can find it at

http://www1.cs.columbia.edu/~lennox/draft-lennox-avt-app-sharing-00.txt

Note that this type of application sharing is application-neutral and 
application-unaware, i.e., this is not a "shared whiteboard" or "shared 
editor" protocol.

We would appreciate your comments and suggestions.

Henning

_______________________________________________
Audio/Video Transport Working Group
[email-masked]
https://www1.ietf.org/mailman/listinfo/avt

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From: Cullen Jennings <[email-masked]>
Date: Tue, 18 Jan 2005 13:33:34 -1000

Interesting stuff. 

Why would you use UDP for this?

Have you had a look at VNC?

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From: Henning Schulzrinne <[email-masked]>
Date: Tue, 18 Jan 2005 18:56:50 -0500

> Why would you use UDP for this?

We anticipate using TCP, namely the connection-oriented transport of 
RTP, in almost all cases, with UDP only in the case where you want to 
distribute the shared application data via multicast.

> Have you had a look at VNC?

Yes, among others, such as T.128. Indeed, our current screen sharing 
application in our SIP client (sipc) is a slightly modified vnc. The 
limitations of that approach partially motivated the work summarized in 
the draft. Among other problems, vnc has its own rather "unique" 
security model, doesn't really support an offer-answer style negotiation 
of pixel "codecs" and only deals with whole-screen sharing, not 
application (window) sharing. We are working on a test implementation, 
probably using vnc as a skeleton.