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From: alan@mn-at1.UUCP (Alan Klietz)
Newsgroups: comp.protocols.tcp-ip
Subject: Re: RCTE
Message-ID: <394@mn-at1.UUCP>
Date: Sun, 4-Oct-87 14:48:39 EDT
Article-I.D.: mn-at1.394
Posted: Sun Oct  4 14:48:39 1987
Date-Received: Thu, 8-Oct-87 00:52:29 EDT
References: <8709281505.AA02244@ucbvax.Berkeley.EDU> <244@mitisft.Convergent.COM>
Reply-To: alan@mn-at1.UUCP (0000-Alan Klietz)
Distribution: world
Organization: Roseville, MN
Lines: 39

In article <244@mitisft.Convergent.COM> andrew@mitisft.Convergent.COM (Andrew Knutsen) writes:
<
<	It seems to me there are is a middle ground in here, between
<char-at-a-time and line- (or screen-) at-a-time, that can be implemented
<purely on the server side using the normal telnet protocol (ECHO negotiation).
<We are considering implementing this for support of low speed TCP links
<(eg async modems), and I'm curious if I'm going to run into some "common
<knowledge problem"...
<
<        The basic idea is to have the kernel (virtual terminal driver) inform
<the telnet daemon when it *would be* doing immediate character echo, and
<not do it.  The daemon turns this information into echo negotiation, which
<the client (hopefully) heeds.  This results in speeded echo response in
<(for example) un*x "cooked" mode, plus a reduction in packet traffic.
<
<	Has anyone tried this? 

We modified the Cray-2 UNICOS kernel to signal a modified (kludged)
version of telnetd on a change in tty state.   For example, when
the user typed "vi" on the Cray-2, the ioctl(TIOCSETA) call is sent
to the pty driver.  The information in the call is stored in a dummy
kernel tty structure and the telnetd process is signaled.  The telnetd
process wakes up and interrogates the terminal state by issuing an
ioctl(TIOCGETA) on the pseudo-tty.  It picks up the info and says
"humm, this user wants raw mode".  It then re-negotiates the ECHO
option with the client to switch to single character mode.

One problem with this approach is that the change of state is
asynchronous to the I/O.

--
Alan Klietz
Minnesota Supercomputer Center (*)
1200 Washington Avenue South
Minneapolis, MN  55415    UUCP:  ..rutgers!meccts!mn-at1!alan
Ph: +1 612 626 1836              ..ihnp4!dicome!mn-at1!alan (beware ihnp4)
                          ARPA:  alan@uc.msc.umn.edu  (was umn-rei-uc.arpa)

(*) An affiliate of the University of Minnesota