Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ames!killer!texbell!sugar!ficc!peter
From: peter@ficc.uu.net (Peter da Silva)
Newsgroups: comp.mail.uucp
Subject: Re: Bidirectional Modem Lines under SunOS 4.0.1
Message-ID: <3773@ficc.uu.net>
Date: 9 Apr 89 16:00:14 GMT
References: <160@osc.COM> <743@key.COM> <2209@laidbak.UUCP> <1403@auspex.auspex.com>
Organization: Xenix Support
Lines: 28

In article <1403@auspex.auspex.com>, guy@auspex.auspex.com (Guy Harris) writes:
> If by "implement callback" you mean "implement a scheme by which
> computer A calls computer B and tells computer B to call computer A
> back", it doesn't cause any problems with that at all; the portion of
> the description which you elided explains why that works.

No it didn't. You described how line-sharing would work, but not how you
can call back and provide a login session. Let's say you have a custom
login program:

	Getty running on ttyXX.
	Phone rings.
	Open completes.
	Getty calls login.
	Login hangs up by closing ttyXX.
	Login opens culXX
	Login calls computer back.
	Login closes culXX and opens ttyXX
	Onwards...

Unfortunately, when login closes culXX it drops DTR. If it doesn't drop
DTR, then how do you hang up after calling, say, uunet? If it does, how do
you hand off back to ttyXX without closing culXX?
-- 
Peter da Silva, Xenix Support, Ferranti International Controls Corporation.

Business: uunet.uu.net!ficc!peter, peter@ficc.uu.net, +1 713 274 5180.
Personal: ...!texbell!sugar!peter, peter@sugar.hackercorp.com.