Re: Need the quote and the author
John C Klensin <klensin@mci.net> Sun, 13 July 1997 13:35 UTC
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Date: Sun, 13 Jul 1997 09:21:23 -0400
From: John C Klensin <klensin@mci.net>
Subject: Re: Need the quote and the author
In-reply-to: <Pine.SOL.3.95.970711072354.7644B-100000@calvin.twntpe.cdc.com>
To: Edward M Greshko <Edward.M.Greshko@cdc.com>
Cc: ietf-smtp@imc.org
Reply-to: John C Klensin <klensin@mci.net>
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On Fri, 11 Jul 1997 07:27:52 +0800 (GMT) Edward M Greshko <Edward.M.Greshko@cdc.com> wrote: > Of course this is not quite related to SMTP...... good. see below. > There is a quote by someone from a time long ago which goes along the > lines of being conservative in what you generate and liberal in what you > receive. In other words, make sure that you follow the specs to the > letter in what you generate, however try to deal with anything reasonable > that you can anticipate being thrown your way. > > I need to know the exact quote and the author. If it is documented > someplace that would be "nice" too. As Tim Goodwin pointed out, the first written form of the comment (that I know of) is in RFC 1123. The quote itself is due to Jon Postel, a _lot_ earlier -- it has been floating around since the early 80s or earlier. As Tim suggests, you need to be quite careful about the quotation and its applicability. It was intended, more or less, as a "smoothing principle: Traditionally, we don't do precise specifications for Internet protocols, especially at the applications level. Instead, we have tried to make things easier to write and understand with less-than-precise syntax rules, a certain amount of handwaving about semantics, general assumptions about goodwill, etc. That is typically ok, if there is some rule about how to handle all of the ambiguities. The robustness principle was, more or less, intended to cover those cases, i.e., if it was possible to read a particular provision in different ways, the sender was expected to read it in the narrowest way feasible while the receiver was expected to give it the most relaxed and broad reading that was feasible. I.e., senders are required to read and follow the specs closely; receivers are to anticipate senders who don't. Virtually every time one looks at a terrible implementation of an Internet protocol that seems to work anyway, the underlying cause is proper behavior using the robustness principle. The problem is that it has been used to justify incredible nonsense, including software authors who have taken the position that receivers are obligated to accept any foolishness that is thrown at them (and therefore the sender is permitted to send such foolishness). That was never the intent, and some of us have argued in a number of specific cases for dropping the robustness principle in favor of a "if bad stuff comes in, bounce it" model, just on the grounds of cleaning up/ preserving the infrastructure. john
- Need the quote and the author Edward M Greshko
- Re: Need the quote and the author Donald E. Eastlake 3rd
- Re: Need the quote and the author Tim Goodwin
- Re: Need the quote and the author John C Klensin
- Re: Need the quote and the author Edward M Greshko