[NNTP] Article Numbers Becoming Invalid (RFC 3977)

[Russ Allbery]

Russ Allbery <rra at stanford.edu> writes:
> Julien ÉLIE <julien at trigofacile.com> writes:

>> If it is really what a news server is supposed to do, then RFC 3977
>> needs to be amended.  Only one additional word is needed:  "the current
>> article number MUST be set to the first *valid* article in the group".
>> Because the first article is currently defined as the reported low
>> water mark -- which is also what INN implements.

> Hm, while that wording change may be useful for clarity, I think that's
> what RFC 3977 already says.  See:

>    The successful selection response will return the article numbers of
>    the first and last articles in the group at the moment of selection
>    (these numbers are referred to as the "reported low water mark" and
>    the "reported high water mark") and an estimate of the number of
>    articles in the group currently available.

> To me, the "at the moment of selection" pretty clearly implies that GROUP
> should be checking and those numbers should really be valid.

> Also, in general it doesn't seem right that one should have to say that
> it must be set to the first valid article in the group.  I think that
> should be implied by saying that it's set to the first article.  A
> number that doesn't correspond to an article isn't really an article.

It's probably worth noting the as-is principle here, though (that being
the general principle in standardization that standards dictate behavior,
and an implementation that behaves in a way indistinguishable from a
conforming implementation is a conforming implementation).  Given that the
client cannot meaningfully distinguish between a server reporting a
correct low-water mark and then that article disappearing and a server not
checking whether the article still exists, and the client has to be able
to cope either way, an argument could be made that checking on group entry
is just a quality of implementation issue.

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