Subject: [NNTP] LISTGROUP extension

From: Matthias Andree <[email-masked]>
Date: Sun, 02 Jan 2005 18:32:53 +0100

Hi,

I am wondering about LISTGROUP semantics WRT cancels and client
behavior.

What happens if the group is modified between the client is sent the
LISTGROUP reply and can send a subsequent ARTICLE/HEAD/BODY/STAT?

I am wondering because section 8.1.1 LISTGROUP/8.1.1.2 Description of
draft 25 snapshot 5 reads "On success, the list of article numbers is
returned as a multi-line response following the 211 response code (the
arguments on the initial response line are the same as for the GROUP
command. The list contains one number per line, is in numerical order,
and lists precisely those articles that exist in the group." (3rd
paragraph).

Note the "precisely", which IMO is an empty promise: Unless "LISTGROUP"
implies some sort of "snapshot" (which it does not), the whole
"precisely" is dead in the water when a write access hits the group -
we'll then have listed an article that has been removed or we my have
omitted a newly arrived article.

Can we reword this paragraph? A first suggestion is "and lists precisely
those articles that exist in the group at the time when the command
arrived at the server. Note that articles may be removed or added to the
group at any time, so a client MUST NOT assume that retrieval commands
for article or details thereof will succeed."  but the standards gurus
may have more background information than I do.

-- 
Matthias Andree

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From: Russ Allbery <[email-masked]>
Date: Sun, 02 Jan 2005 11:19:51 -0800

> LISTGROUP reply and can send a subsequent ARTICLE/HEAD/BODY/STAT?

Then the article may not exist.

> may have more background information than I do.

Note that we've closed discussion of this part of the draft, but I don't
want that to get in the way of making simple clarification changes if
everyone thinks they're okay.  I think the first part of your rephrasing
is fine, and if this seems completely uncontroversial to everyone else,
I'm fine with Clive making that change.  I don't think the second sentence
is really necessary.

-- 
Russ Allbery ([email-masked])             <http://www.eyrie.org/~eagle/>

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From: Matthias Andree <[email-masked]>
Date: Sun, 02 Jan 2005 21:19:57 +0100

> Note that we've closed discussion of this part of the draft, but I

I've been passing on a question that arose on the leafnode mailing list
earlier today.

> I'm fine with Clive making that change.  I don't think the second sentence

Fine. Thank you.

-- 
Matthias Andree

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From: "Clive D.W. Feather" <[email-masked]>
Date: Mon, 3 Jan 2005 09:35:26 +0000

> I'm fine with Clive making that change.  I don't think the second sentence

I don't like "when the command arrived at the server", because there may be
a delay before processing.

GROUP (6.1.1.2) uses the words "at the moment of selection" and I think
that's better, so I'm going to use it:

    The list contains one number per line, is in numerical order, and
    lists precisely those articles that exist in the group at the moment
    of selection.

The second sentence is unnecessary - 6.1.1.2 describes things well enough
and LISTGROUP defers to it in these aspects.

-- 
Clive D.W. Feather  | Work:  <[email-masked]>   | Tel:    +44 20 8495 6138
Internet Expert     | Home:  <[email-masked]>  | Fax:    +44 870 051 9937
Demon Internet      | WWW: http://www.davros.org | Mobile: +44 7973 377646
Thus plc            |                            |

---

From: Matthias Andree <[email-masked]>
Date: Mon, 03 Jan 2005 16:40:30 +0100

> and LISTGROUP defers to it in these aspects.

Excellent. Thank you!

-- 
Matthias Andree