nntp-extensions feedback on draft-ietf-nntpext-dynfeed-00.txt

[Brian Hernacki]

Just a couple thoughts after a quick reading. While I think the idea of
adding a dynamic feed control method to the protocol is long overdue,
I'm not sure this is the way to do it. Maybe the draft just needs to be
clarified.

First, it's not clear how this concept fits into the whole picture. Do
two servers exchange feed information periodically? Is it done at the
beginning of each feed session?

Second, I think the lack of positive control ("just send me comp.*") is
bad. Feeds are generally specified as positive patterns, not negative.

I'd put some thought into dynamic feed control a little while ago and
the notion I'd been settling on was an additional set of verbs which
servers would use at some periodic interval (seperate from the feeds
sessions) to communicate feed changes. Picture two servers A and B. A
wants B to stop sending it the alt.* groups, so it opens up a connection
and tells B that. It would go something (roughly) like:

A: <connects to B>
B: <NNTP greeting>
A: LIST EXTENSIONS
B: 215 Extensions supported by server.
   FEEDCONTROL
   .
A: FEEDCONTROL LIST
B: XXX feed speciciation for server A
   GROUPS alt.*,comp.*,rec.*
   DIST !local
   .
A: FEEDCONTROL GROUPS comp.*,rec.*
B: XXX OK, change made

At this point server A would stop queueing up articles from alt.* to
send to B. This seems pretty lightweight since it would only be fired
when changes need to be made.

--brian