A socket question

[Steve Holden]

"Robin Munn" <rmunn at pobox.com> wrote ...
> On 15 Jan 2002 15:13:20 GMT, Ng Pheng Siong <ngps at madcap.netmemetic.com>
wrote:
> >According to Robin Munn <rmunn at pobox.com>:
> >> "exceptional conditions" (I don't know what constitutes an "exceptional
> >> condition" on a TCP/IP socket; one of the RFC's should be able to tell
> >> you).
> >
> >OOB data. On the wire these will be TCP segments with the URG flag on.
>
> Thanks! I've never written an application where out-of-band data was
> necessary, so I didn't know that. Has anyone used this in practice? What
> is it good for?
>
In practice, not a lot. But consider a Telnet client, for example. Suppose
the user types commands ahead, one of which places her shell interpreter
into an infinite loop. The client can't simply queue a "^C" character to the
server, because it would sit there in the buffer stream forever. So it sends
out-of-band data, which the server can respond to without processing
everything that preceded it.

regards
 Steve
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