[NNTP] Article Numbers Becoming Invalid (RFC 3977)

[Russ Allbery]

Julien ÉLIE <julien at trigofacile.com> writes:
> Hi Russ,

>>>   If the current article number is already lower or equal to the lowest
>>>   existing article number (if any) in the newsgroup, a 422 response MUST
>>>   be returned.
>>
>> Shouldn't we go ahead and use the same terminology?  Something like:
>>
>>    If the current article number is invalid, a 420 response MUST be
>>    returned.  If the current article number is equal to or lower than the
>>    reported low water mark, a 422 reponse MUST be returned.  [...]
>>
>> This also reverses the order so that it's clearer that an invalid article
>> number takes precedence in determining the return code.

> The change of order is indeed better.

> With the wording using the low water mark, I have doubts whether people
> won't get confused.  It implies that the low water mark is moving without
> actually being *reported* (after GROUP, the server says 12 so it is the
> reported low water mark; and if article 12 is cancelled, then the low
> water mark is 13 but the server does not mention it to the client).

Oh, yes, that's the bit that I was missing.  Good point.  How about:

    If there are no articles available with an article number lower than
    the current article number, a 422 response MUST be returned.

That makes it slightly more concrete.  What we're after is whether there
are any articles to meaningfully return, and comparisons of article
numbers are just a means to get to that end.

Ideally, we would have defined available somewhere as "retrievable by
ARTICLE."  I suppose I'm introducing the term "available" and your wording
above is introducing the term "lowest existing article number" and it
depends on which one seems clearer.

I think the thing that was giving me pause about your proposed wording was
that it sounds a little like "lowest existing article number" might mean
something different than "number of the lowest existing article."

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