UDP for pixel data transmission

[Will Dean]

At 09:56 11/02/2000 +0100, you wrote:

>I have an idea and I hope that somebody could tell me if it is a good
>one or not :
>
>VNC uses TCP to send all messages between server and client.
>Why not keep TCP to send "important" messages (like Version numbers and
>authentication) and send update rectangles which are very numerous, by
>UDP ?

The most significant advantage of UDP over TCP is that you don't have to go 
through a performance to establish a connection each time you want to send 
data.  VNC doesn't break and re-establish a TCP stream each time it sends a 
rectangle, so there wouldn't be a create deal saved.  It opens a socket 
when you connect a client and then disconnects it when you disconnect.

The main disadvantage of UDP is that packets can go missing without anyone 
knowing - this might not matter for VNC mouse updates, but would, in 
general, be unacceptable.  (Try considering a text editor where some of the 
characters were updated and some weren't.)

Myself, I can't see much mileage in it, but I might have missed something.

Cheers,

Will


--
Will Dean - Industrial Computing Ltd
Cambridge, UK


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