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RE: Host header issue

From: Larry Masinter <masinter@parc.xerox.com>
Date: Mon, 6 Sep 1999 13:14:56 PDT
To: "Josh Cohen (Exchange)" <joshco@exchange.microsoft.com>, <Albert-Lunde@nwu.edu>
Cc: <http-wg@hplb.hpl.hp.com>
Message-ID: <000701bef8a4$7cdf8160$c5d1000d@copper.parc.xerox.com>
The reasoning for the MUST requirement for the Host header
was to leave absolutely no ambiguity for whether/when it
was required, and to ensure that there sufficient servers
that required it to force individuals to upgrade their clients
if they had clients that didn't send it.

Adding this requirement was imposed by the IESG; I don't
think it was originally the consensus of the HTTP working
group to do so.

The arguments you've given against the requirement are
primarily ones of 'general design principles'. If you
were to develop or deploy a server that did not follow
this guideline, you'd have a non-compliant server that
was interoperable with all compliant clients, in addition
to being interoperable with some non-compliant clients.
That's good implementation advice in general, but there
are occasionally reasons to violate general design principles.

You might be able to convince the IESG to drop the requirement
in the case where an absolute URI is supplied, but it's
my guess that the answer will depend on how successful the
original attempt to change user behavior through requirements
on server compliance has been. Are there sufficient 
compliant HTTP servers around that users have upgraded
their clients? My impression is 'no'.

Larry
Received on Monday, 6 September 1999 21:15:41 EDT

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