[NNTP] Article Numbers Becoming Invalid (RFC 3977)

[Julien ÉLIE]

Hi Sabahattin,

> the only use for code 420 is after commands following entering
> an empty group, since it's impossible to invalidate the article
> pointer by any other means.

ARTICLE
220 100 <example at mid> article follows
[...]

Suppose you wait for two minutes and the article is cancelled
during that period, and you issue again the command:

ARTICLE
420 No current article selected


The article pointer has been made invalid (though it still points
to 100).


It is the same thing that happens when you send a GROUP command
and the first valid article in the newsgroup is not the reported
low water mark.  The article pointer points to the reported low
water mark, and is therefore invalid.  You have a 420 error.
NEXT will give you, if the group is not empty, the first valid
article in the newsgroup.

It is how it currently works, at least with INN.  But it should
be clarified in RFC 3977.

** Note that maybe INN is wrong! **


One interesting thing I have just discovered is that the NNTP
reference implementation returns the FIRST VALID ARTICLE when
ARTICLE/BODY/HEAD/STAT is sent!