[NNTP] Article Numbers Becoming Invalid (RFC 3977)

[Sabahattin Gucukoglu]

On 31 Dec 2009, at 05:44, Russ Allbery wrote:
> Sabahattin Gucukoglu <mail at sabahattin-gucukoglu.com> writes:
>> But, and I hate to be a nuisance about this, my question is still not
>> quite answered: if I cannot manipulate the article pointer while an
>> invalid article number is the next to be fetched, how can I really use
>> NEXT?
> 
> Unless the group is empty, the article number is guaranteed to be valid
> when you enter a group with GROUP.  NEXT sets the article number to the
> next valid article.  It will skip over any invalid article numbers for
> you.  So if you do:
> 
> GROUP example.test
> ARTICLE
> NEXT
> ARTICLE
> NEXT
> [...]
> 
> until you get a 421 error from NEXT, you will traverse every article in
> the group.  You may still get a 420 error from ARTICLE if the currently
> selected article disappears between NEXT and the ARTICLE command, but NEXT
> should still work.  I don't believe NEXT can return 420 unless the group
> was empty when the GROUP command was issued.

Right, this is fine.  But the question was really, how do I initialise the pointer to something not the beginning of the group?  I cannot use NEXT until I hit on a valid article.  Does this not mean that I will have to find it by trial and error with article numbers?

So, I want to retrieve articles beginning from 1000 in example.group.  I would do:
GROUP example.group
ARTICLE 1000
ARTICLE 1001
...
until I get a working article (not 423)
and then I can proceed to use NEXT.

A coinciding question: if I use the ARTICLE command specifying an invalid article number, has the state of the server changed so that NEXT will now no longer work, or will it work as it did before I issued ARTICLE, assuming a valid article before (as on GROUP)?

Cheers,
Sabahattin