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From: acs@amdahl.uts.amdahl.com (Tony Sumrall)
Newsgroups: comp.sys.amiga,comp.sys.amiga.tech
Subject: Re: IPC for Protocols in Terminal Emulators
Message-ID: <26736@amdahl.uts.amdahl.com>
Date: 5 Apr 88 20:59:28 GMT
References: <Apr.2.13.17.28.1988.2684@topaz.rutgers.edu>
Reply-To: acs@amdahl.uts.amdahl.com (Tony Sumrall)
Organization: Amdahl Corporation, Sunnyvale CA
Lines: 41
Keywords: IPC remote protocol FTP
Summary: Why? How does it *help* the end user?

In article <Apr.2.13.17.28.1988.2684@topaz.rutgers.edu>
mccarrol@topaz.rutgers.edu (Mark C. Carroll <MC>) proposes a standard IPC
protocol for file transfer programs.  I'm implementing external xfer pgms
in VT100 R2.9 *now* and am *not* doing anything near what's proposed. What
I *am* doing is allowing the user to specify the complete command that is
to be used to invoke the external program (complete with replaceable host
and local file names).  The reasons that I'm not doing IPC are pretty
simple:
    1)  I don't see what having an IPC will buy the user (in this case).
	I need to be convinced that implementing such a beast will actually
	benefit the end user.  (Yes, I'll read follow-ups.)
    2)  My method won't require any modification to the external pgm.  You
	could write an external comm pgm in BASIC if you wanted and it
	should work just fine. If a commercial comm pgm has a protocol
	that you feel you need, just invoke it.
    3)  You don't have to learn the IPC protocol just to build your
	external xfer pgm.
    4)  My method accomplishes the job with a minimum of effort (on my
	part) and a minimum of effort on the part of the developer of the
	external xfer pgm.
    5)  The standard doesn't exist yet.
As far as the proposal itself, I have a few questions:
    1)  How many bytes of data is the owner of the serial port supposed to
	bundle up into the message that it sends to the external pgm?
    2)  How does the SP owner (serial port owner) know that the external
	pgm is finished?  or abended?
    3)  How does the SP owner know when to send the client a TIMEOUT msg?
    4)  How does the client know the pertinent settings of the serial port
	(e.g. parity, baud rate, break time, end-of-line chars)?
    5)  How does the SP owner quiesce the client (in case the user decides
	to abort the xfer or the user detects a loop or other failure in
	the client)?
I'm not saying that I won't implement IPC in a later version...I will if
and when it becomes stable and I can discern a tangible benefit to the
end-user.

-- 
Tony Sumrall acs@amdahl.uts.amdahl.com <=> amdahl!acs

[ Opinions expressed herein are the author's and should not be construed
  to reflect the views of Amdahl Corp. ]