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Path: utzoo!mnetor!seismo!umcp-cs!cvl!umd5!zben
From: zben@umd5 (Ben Cranston)
Newsgroups: net.mail
Subject: Re: Domains: Multiple names OK? (Really, are domains good)
Message-ID: <1246@umd5>
Date: Mon, 15-Sep-86 21:27:07 EDT
Article-I.D.: umd5.1246
Posted: Mon Sep 15 21:27:07 1986
Date-Received: Tue, 16-Sep-86 02:10:26 EDT
References: <566@mecc.UUCP> <2502@cbosgd.UUCP> <3920@ut-ngp.UUCP> <3044@columbia.UUCP> <3437@umcp-cs.UUCP>
Reply-To: zben@umd5.umd.edu (Ben Cranston)
Organization: University of Maryland, College Park
Lines: 59
Summary: Claimed U of Maryland is in fact only CS Department

In article <3437@umcp-cs.UUCP> israel@umcp-cs.UUCP (Bruce Israel) writes:

> My point is that you don't require extra complexity from users unless
> it's necessary.  If there is only one SEISMO, then mail person@SEISMO
> should translate out to person@SEISMO.CSS.GOV.  If there are more,
> then mail to that address should return an ambiguous address message,
> so that the user could more completely specify the address.

As I am rapidly becoming blue in the face repeating, this is a prescription
for a (perceived) breakdown in the future, when the second Seismo comes along 
and the user perceives that "something that used to work dont any more".

> Case in point: The University of Maryland mail system.

In point of fact Bruce maintains mail for the Department of Computer Science's
machines (this becomes important later).  I maintain the software at UMD2 and
various people maintain the software on our Unix machines, most notably Louis
Mamakos.  Bruce Crabill does the dirty work on the IBM mainframes.

> I have it set up to work as follows:
> 'mail user' will go to the user on the current machine, if he exists.
> If not, it will go to the machine on our local network that the user's
> account is on.  These tables are kept up to date automatically.  The
> rationale is that users should not have to remember on which machine
> another local user lives.

This can be done because the Computer Science Department's users are limited
in number and closely communicate.  What works for 100 users does not always
work for 10,000 (consider the N log N time to sort their names, for example).

In particular, the Department owns its own machines, and can make the rule:
"if there exists a jim@foo and a jim@bar they are the same person!" stick.
With every department on campus owning its own computers, *I* cannot make
such rules.  Thus this scheme cannot in the general case be make to work.
 
> 'mail person@arpa-site' will go to the arpanet site.
> ... 
> 'mail person@uucpsite' will expand uucpsite to the pathalias route...

And what, pray tell, happens if there is a name that belongs to both the
Internet and UUCP name spaces?  One takes precedence over the other?  If
so, then a new name popping up in the superior domain deactivates the same
name in the inferior domain.  Users come to you and say "Yesterday I could
send to bob@bozo but today it doesn't work any more!".

It's a good thing you don't have to support any REAL users...
 
> Bruce Israel
> University of Maryland, Computer Science Dept.
> {rlgvax,seismo}!umcp-cs!israel (Usenet)    israel@Maryland (Arpanet)

Ben Cranston
University of Maryland, Computer Science Center
Systems Programming Group                ^^^^^^

-- 
                    umd5.UUCP    <= {seismo!umcp-cs,ihnp4!rlgvax}!cvl!umd5!zben
Ben Cranston zben @ umd2.UMD.EDU    Kingdom of Merryland Sperrows 1100/92
                    umd2.BITNET     "via HASP with RSCS"