[NNTP] Thoughts on article number resetting/rollover

[Ken Murchison]

The whole discussion of the 2^32 limit for article numbers and rollover 
got me thinking a little.  Rolling the numbers over is really no 
different than if the server unilaterally resets the article numbers for 
some reason (server crash, software change/upgrade).  Obviously admins 
try to avoid this at all cost, but I'm sure it happens.  In either case, 
the server should have some mechanism to tell the client that the 
article numbers have changed, and that any cached data that it has is 
invalid.

We need look no farther than IMAP (which also has a 2^32 limit for 
article/message numbers BTW) for a solution.  Each mailbox on an IMAP 
server has a UIDVALIDITY metadata item (usually a timestamp).  Any time 
the existing UIDs of a mailbox are reset/reordered, the server changes 
the UIDVALIDITY on the mailbox (new messages appended to the mailbox 
does NOT cause any change to UIDVALIDITY).  When the client sees a 
change in the UIDVALIDITY, it flushes its cache and re-reads the mailbox 
to get the new message UIDs and contents.

A mechanism like this seems like a pretty trivial extension to NNTP (one 
extra param in the GROUP, LISTGROUP, and LIST ACTIVE responses) and 
would solve both the rollover and resetting of article numbers problems. 
  This extension would be orthogonal to any BIGNUM extension and could 
co-exist peacefully.

Thoughts?

-- 
Kenneth Murchison     Oceana Matrix Ltd.
Software Engineer     2495 Main St. - Suite 401
716-604-0088 x26      Buffalo, NY 14214
--PGP Public Key--    http://www.oceana.com/~ken/ksm.pgp