[NNTP] LISTGROUP

[Russ Allbery]

Mark Crispin <MRC at CAC.Washington.EDU> writes:

> I think that I've expressed my dismay at NNTP's abuse of 4xx codes
> before, and 411 and 412 are no exception.  412 in particular offends me;
> if this isn't properly a 5xx code I have a hard time thinking of what
> would be.

So... I've tried to explain a few times that NNTP does not use the 400 and
500 conventions of other protocols like SMTP.  NNTP can't be abusing
something that it never followed and never even tried to follow in the
first place.  Are you not agreeing with my point, not understanding it,
not remembering it...?  I feel like I've tried to respond to this point on
multiple occasions now, with apparently no change in your perception that
NNTP thinks of 4xx as "temporary" and gets it wrong.  4xx has never meant
temporary, or 5xx permanent, in the history of the NNTP protocol.

If we were redoing the protocol from scratch, we'd use the same return
code conventions as everyone else, but since we're not and since changing
all the return codes obviously can't happen, I guess I don't see a lot of
utility in discussing it.

Anyway, LISTGROUP uses 411 and 412 in the way that every other command in
NNTP with those error conditions does.

> Can we get rid of that "estimated" from "estimated number of articles in
> the group"?  As far as I am concerned, an estimated value is worse than
> useless, and an NNTPv2 compliant server should be required to give an
> exact value.

An exact value at the time that the command is issued that may have
changed a second later doesn't strike me as much more useful than an
estimated value.  Anyway, no, we can't change this and stay within the
charter of the working group (even putting aside the question of whether
it's a feasible change to expect software to do).

> What is a "reported" high and low water mark as opposed to a high and
> low water mark?

Same thing.  I'm not sure why the word "reported" is there, but it's used
fairly consistently through the rest of the draft as well.

> In a range, how is 5-1 interpreted?  Is it equivalent to 1-5?

> Note that if 5-1 is equivalent to 1-5, then 5- is equivalent to 4-5 if 4
> is the highest article number (and you need to change that "all
> following" text).

> If it is it an error, then there needs to be an error code.

That's a very good question, and one that we also need to answer for OVER,
which has the same issue.  INN historically (all the way back to 1.0!) has
treated 5-1 as 5-, or in general n-m where m < n as equivalent to n-.  I
don't know if that's something we want to bless.  There is no error,
though.

> Should lists of article numbers/ranges be allowed, e.g. 1-5,14-34,56- ?

No, they're not allowed anywhere else that ranges are allowed.

> Your first two examples have two extraneous spaces after the command.
> Are these significant for some reason?

I think they were intended to be examples that whitespace doesn't matter
(they're in the existing LISTGROUP writeup).

> Your first example is really of a "never posted to group" instead of an
> "empty group".  You probably should have a separate empty group example.

It could be either; see 6.1.1 where this is discussed.  One of those
places where we're documenting existing practice, and while we have some
leeway to revisit some of this given the NNTPv2 capability, this is really
not one that I want to reopen; we need to finalize and publish something
soon.

> Your second, third, and fourth examples show estimates for the number of
> articles, and back up my point about the overall uselessness of the
> estimates.  Please let's have exact values.

At least one of those should probably be changed to show an exact value; I
wasn't thinking about that when I copied and pasted the examples.

-- 
Russ Allbery (rra at stanford.edu)             <http://www.eyrie.org/~eagle/>