Re: [arch-d] Proposed IAB program: Evolvability, Deployability, & Maintainability.
John C Klensin <john-ietf@jck.com> Wed, 22 July 2020 16:54 UTC
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Date: Wed, 22 Jul 2020 12:31:15 -0400
From: John C Klensin <john-ietf@jck.com>
To: Stephen Farrell <stephen.farrell@cs.tcd.ie>
cc: Brian E Carpenter <brian.e.carpenter@gmail.com>, Tommy Pauly <tpauly@apple.com>, architecture-discuss@iab.org
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Subject: Re: [arch-d] Proposed IAB program: Evolvability, Deployability, & Maintainability.
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Stephen and Tommy, Sorry it has taken me so long to get to this, but, at least from my perspective, your question (if I understand it correctly) has some interesting answers. These are my opinions only but it may be worth noting that, although I helped with RFC 1123 and was involved in other ways much earlier, I was dragged into the IETF precisely to work on email protocols. Inline below. --On Tuesday, 07 July, 2020 02:14 +0100 Stephen Farrell <stephen.farrell@cs.tcd.ie> wrote: > > Hi Brian, > > (Maybe not directly a question for you but...) > > On 06/07/2020 23:05, Brian E Carpenter wrote: >> SMTP has been the classical example for many years, and I >> suspect that RTCWEB might furnish another good example of >> this problem before long. > Do we have evidence as to the (good, bad or neutral) impact > of the stately pace of the evolution of email standards- > track RFCs? I could imagine the net effect being overall > positive or negative but am unsure which may be the case. I > suspect it may be more likely that the actual impact is not > correlated with RFC numbers at all, but that may also be > wrong. Once upon a time, it was a maxim of ARPANET and Internet protocol design that things were to be kept simple, with a minimum of options, alternate ways to do the same thing, and so on. Part of that was (or became) a deliberate contrast with a well-known reference model and protocol suite that were so full of options and variations that almost no one could implement them and it was impossible to tell whether failure to interoperate was a bug or the result of, e.g., difference choices of options or profiles. The designers of Internet email had the added advantage of experience with email systems that served users on a single host and some that served a set of related hosts running the same operating system software even before the mail command was introduced into FTP. Even the envelope-header split came rather last in the game. The implication of that was that, by the time RFCs 821 and 822 came along and the former was followed by RFc 974, they were based on years significant implementation, deployment, and user experience, including experience with gateways, _and_, by today's standards, they were still rather simple protocols. The changes of the early 1990s were necessitated by new requirements -- for multilingual and multimedia mail and for the ability to do a number of things that the original protocols did not facilitate doing in an interoperable way.. and to do so in a way that would not break the existing widely-deployed infrastructure. Even then we made what may have been design errors (or not). For example, in allowing extensions we failed to distinguish clearly between "I, the server, am offering these extensions" and "I the server will not accept your mail unless you support these extensions" and, in MIME, we specified a header field of "MIME-version: 1.0" without any non-destructive plan about what a different number might mean. The next two iterations were just consolidation of multiple specifications and clarifications. And the work now being contemplated (see the "emailcore" BOF on the IETF 108 agenda) is intended to be limited to clarifications and fixing errors and we just haven't felt pressure to do it much earlier. IMAP, for example, is different -- more options, more commands, and more working groups adding yet more options. Now, contrast that situation with, e.g., SIP, HTTP/HTTPS, or RTCweb and, well, it is an interesting contrast. I hope everyone participating in this discussion has read Fred Brooks on second system effects and perhaps thought a bit about what it means to patterns of standards development. john
- [arch-d] Proposed IAB program: Evolvability, Depl… Tommy Pauly
- Re: [arch-d] Proposed IAB program: Evolvability, … Toerless Eckert
- Re: [arch-d] Proposed IAB program: Evolvability, … Brian E Carpenter
- Re: [arch-d] Proposed IAB program: Evolvability, … Toerless Eckert
- Re: [arch-d] Proposed IAB program: Evolvability, … Stephen Farrell
- Re: [arch-d] Proposed IAB program: Evolvability, … Brian E Carpenter
- Re: [arch-d] Proposed IAB program: Evolvability, … Joel M. Halpern
- Re: [arch-d] Proposed IAB program: Evolvability, … Brian E Carpenter
- [arch-d] Re: Proposed IAB program: Evolvability, … Martin Thomson
- Re: [arch-d] Proposed IAB program: Evolvability, … S Moonesamy
- Re: [arch-d] Proposed IAB program: Evolvability, … Tommy Pauly
- Re: [arch-d] Proposed IAB program: Evolvability, … Tommy Pauly
- Re: [arch-d] Proposed IAB program: Evolvability, … Tommy Pauly
- Re: [arch-d] Proposed IAB program: Evolvability, … Toerless Eckert
- Re: [arch-d] Proposed IAB program: Evolvability, … S Moonesamy
- [arch-d] Re: Proposed IAB program: Evolvability, … Christopher Wood
- Re: [arch-d] Proposed IAB program: Evolvability, … Spencer Dawkins at IETF
- Re: [arch-d] Proposed IAB program: Evolvability, … Mary Barnes
- Re: [arch-d] Proposed IAB program: Evolvability, … Spencer Dawkins at IETF
- Re: [arch-d] Proposed IAB program: Evolvability, … Brian E Carpenter
- Re: [arch-d] clusterpation, was Proposed IAB prog… John Levine
- Re: [arch-d] clusterpation, was Proposed IAB prog… Brian E Carpenter
- Re: [arch-d] clusterpation, was Proposed IAB prog… John R Levine
- Re: [arch-d] clusterpation, was Proposed IAB prog… Toerless Eckert
- Re: [arch-d] clusterpation, was Proposed IAB prog… John R Levine
- Re: [arch-d] clusterpation, was Proposed IAB prog… tom petch
- Re: [arch-d] Proposed IAB program: Evolvability, … John C Klensin
- Re: [arch-d] clusterpation, was Proposed IAB prog… Toerless Eckert