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From: mark@cbosgd.UUCP (Mark Horton)
Newsgroups: net.lan
Subject: Re: Xerox NS or Courier for UNIX?
Message-ID: <549@cbosgd.UUCP>
Date: Mon, 7-Nov-83 14:21:57 EST
Article-I.D.: cbosgd.549
Posted: Mon Nov  7 14:21:57 1983
Date-Received: Wed, 9-Nov-83 00:00:14 EST
References: <1668@fortune.UUCP>, <478@cbosgd.UUCP>, <1897@gatech.UUCP>
Organization: AT&T Bell Laboratories, Columbus
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Skip, if you have a published copy of the higher level layers for XNS
(e.g. everything above the transport level) I'd sure like to hear about
it.  My understanding is that Xerox will not release the specs for the
higher layers, because they want you to buy Xerox computers that implement
the layers and not to be able to use any other vendors computers.  This
alone is the kiss of death, as far as I'm concerned.  Of course, if I'm
wrong I'd like to know about it.  My Xerox literature claims they have a
5 level architecture, with only levels 0, 1, and 2 (physical, internet
datagram, and 5 protocols including sequenced packet and packet exchange)
published.  Level 3 includes courier (which I gather is a session layer
protocol) and implies that all the application layer protocols do not
matter.  (I see this attitude with a lot of vendors - they think you are
going to provide your own application level software and make not attempt
to standardize it.)

My impression is that the only network protocol suite that documents the
standards all the way up to the application layer is TCP/IP.  They have
a standard for remote login; a standard for file transfer; a standard
for electronic mail; a standard for a nameserver; even standard for
Mickey Mouse protocols like time of day, who is logged on, a quote of
the day, data sink, data generator, echo server, and so on.  This does
not provent you from inventing new application protocols (e.g. Berkeley
UNIX has added remote execution) but standardizes the ones that everybody
is going to want.  I'm sure they must exist with XNS too, but they do not
seem to be publicly documented.
	
	Mark Horton