[Tsvwg] Re: [e2e] What's the benefit of out-of-order processi

[John Wroclawski]

At 6:36 PM -0700 9/17/01, Jacob Heitz wrote:
>The urgent pointer does not point at a range, only at a single
>byte. It can only deliver a single byte of out-of-band data.
>

Actually, TCP urgent delivers an out of band _notification_ of the 
presence of urgent _in band_ data.

(The idea being that on receiving the notification the app would know 
to chug through the data stream in whatever way it sees fit until it 
gets to the 'urgent' part.)

This was a well defined, useful semantic for canceling or aborting 
the processing of previously queued data - see telnet. But long ago 
various folks tried to contort it into actually delivering the data 
out of band. Since the protocol mechanism wasn't designed for that, 
it never worked very well, different implementations had different 
bugs/limitations, and things went downhill from there.

cheers,
john