Re: draft-farrell-ft-01.txt -- what signal are we attempting to sense?

Stephen Farrell <> Wed, 05 December 2012 17:58 UTC

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Date: Wed, 05 Dec 2012 17:58:25 +0000
From: Stephen Farrell <>
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To: Ted Hardie <>
Subject: Re: draft-farrell-ft-01.txt -- what signal are we attempting to sense?
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Hi Ted,

On 12/05/2012 05:22 PM, Ted Hardie wrote:
> Reading through Stephen's draft and the discussion to date, I think there
> is some confusion/disagreement about what it is having an implementation
> at this stage signals.
> One way to break up the work of the IETF is:
> Engineering--making decisions about the trade-offs related to
>              different approaches to solving a problem.
> Specification--producing text that describes how to inter-operate with
> others.
> Standardization--describing the applicability of a specification or
>          its suitability as the basis of other work
> (Since we reflect all of these in the same document production, it's
> really muddier than this, but bear with me)
> My experience is that people implementing during the working group
> discussion phase generate really useful data about the engineering;
> they can tell you the real impact of different trade-offs, so that
> this isn't based on general experience.  But it's not such a great
> signal about the specification itself, since the spec is designed to
> be usable by folks who were not part of the working group process.

Good point.

> Stephen's draft says:
>    Note also that this experiment just needs an implementation that
>    makes it possible for the WG chairs and responsible AD to verify (to
>    the extent they chose) that the implementation matches the draft.
> and later:
>    An implementation of the draft (ideally open-source) is required
>    for fast-track last-call.  If there is no implementation or if the
>    implementation is unavailable or does not implement the draft
>    sufficiently closely then the document needs to be returned to the
>    WG.  This only requires one implementation, not two and the WG
>    chairs and responsible AD decide themselves how much validation is
>    required for this.
> Given the "sufficiently closely" and the timing of production, I
> assume that the signal we're looking for here is confirmation of the
> engineering choices.  I think that's fine (though I'm not sure this
> needs formal experiment status).  

I hadn't thought about this in terms of signals, but its an
interesting way to look at it.

BTW, others have also said (and I agree) that lots of the things
suggested in the draft don't need to be a formal experiment,
but I think doing it that way has merit in any case.

> But I believe we need to be really
> careful that it isn't mistaken for signal about the specification's
> quality.  It can happen that a working group has "lore" about what to
> do that gets folded into the implementations done by those
> participating, but which never quite makes it into the spec "because
> everyone knows it".  An implementation written during the working
> group process is potentially subject to this effect.
> An interoperating implementation written to the spec by a non-working
> group participant would be great signal about the specification quality,
> but it  is not likely to be available at the stage of the process this
> draft
> targets.

That's very true.

I guess I'd be a bit reluctant to try to add text to the
draft about this though, since it might be a bit of a rathole
to try discuss generic good/bad aspects of implementations
and specs. I could see that discussion running and running
and getting nowhere;-)

But maybe it'd be a good idea to maintain a wiki as the
experiment runs where such things could be captured that
could feed into later evaluation of how things went.

If that sounds useful, I'm willing to start that (maybe
once the draft's gotten past IETF LC) and add a bit of text
to the draft pointing at the wiki page. I'm also happy to
do some maintenance on that as things progress, if they do.

If you think some other changes would help instead or
as well, I'll gladly take text of course, or suggestions
for how to (re-)structure the text.


> Again, not objecting to the experiment; I just want to be clear about
> what signal we believe we're getting from the implementation.
> Just my two cents,
> Ted