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Path: utzoo!watmath!clyde!akgua!mcnc!decvax!harpo!ulysses!burl!hou3c!SIRBU@Mit-Mc.ARPA
From: SIRBU@Mit-Mc.ARPA ("Marvin A. Sirbu, Jr.")
Newsgroups: net.mail.msggroup
Subject: Re: New topic, name domains vs. IFIP "user-friendly" non-domain names
Message-ID: <564@hou3c.UUCP>
Date: Fri, 11-May-84 17:56:00 EDT
Article-I.D.: hou3c.564
Posted: Fri May 11 17:56:00 1984
Date-Received: Thu, 17-May-84 05:23:40 EDT
Sender: ka@hou3c.UUCP (Kenneth Almquist)
Lines: 45
To: deepthot!julian@seismo
Cc: jbs@Mit-Xx.ARPA, MsgGroup@Brl-Mis.ARPA

The domain style names are no more "addresses" than are IFIP style
names.  It is perfectly plausible for there to be domain style names
of the form "Julian_Davies.University_of_Western_Ontario.Canada."
All that is required is a top level domain named Canada that contains a
subdomain named University_of_Western_Ontario, etc.  This domain name
would then map into a mail forwarder or host where you read your mail.


The differences have to do not with what is a name and what is an
address, but rather what is the object that the two types of names are
in fact names of.  Domain style names are names of host computers.  IFIP
style names are names of "User Agents" which are mail processes running on
either a personal workstation or a shared host.  To fully identify a
mail process using domain style domains, one has to say something like, 
Davies@Julian_Davies.University_of_Western_Ontario.Canada in order to
identify the process on the host
Julian_Davies.University_of_Western_Ontario.Canada.

The other difference has to do with attaching a specific semantics to
the various components.  In domain style names, there is no semantics
associated with the subdomain University_of_Western_Ontario.  In IFIP
style names, this would be specified as a locale or an organziation.
What is the value of specifying some semantics?  It might make it easier
to guess.  It also forces databases to be organized by the particular
semantics chosen, instead of whatever happened to be convenient.  For
example, there is no reason why Internet_protocol_czar.ARPA couldn't be
a valid name for Jon's personal workstation; indeed this might even be a
sensible thing to do from a Hamming code point of view if Jon gets lots
of messages.  The  IFIP proposal doesn't provide a semantic category for
Internet_protocol_czar and thus could not accept a name of that form.

For implementation reasons, the semantic categories must be arranged in
a hierarchy.  This then leads to the requirement that the top layer in
the hierarchy must have entries for ALL valid values of the next
semantic level.  This imposes constraints on the ability to agregate
levels on the basis of administrative or operational performance reasons
as opposed to for reasons of name structure.  Thus, if semantic
categories are country, city, address, person, that works fine for
France.Paris.Kennedy_Blvd.John_Doe, but not for
USA.Paris.Kennedy_Blvd.John_Doe, because you need another level of
hierarchy -- State names -- to CONVENIENTLY disambiguate, at least in
the US.  Domain names give you more flexibility to define categories as
you please.

Marvin Sirbu