ietf-nntp New wording on article numbers - draft 2

[Jack De Winter]

>    If the group is empty, one of the following three situations will
>    occur. Clients MUST accept all three cases; servers MUST NOT represent
>    an empty group in any other way.
>    (1) The high water mark will be one less than the low water mark,
>    and the estimated article count will be zero. Servers SHOULD use this
>    method to show an empty group. This is the only time that the high
>    water mark can be less than the low water mark.
>    (2) All three numbers will be zero.
>    (3) The high water mark is greater than or equal to the low water mark;
>    the estimated article count might be zero or non-zero.
>
>Is (3) really needed?  Does anything operate that way now?  I think
>the world would be a happier place if "count == 0" implied an empty
>group, always...   Oh, I see you're allowing for a server not
>realising that a group is empty and simply doing the subtraction
>thing, and yet want to allow for the group being empty.   I'm not
>sure that's worth the effort - simply make sure that it is clear
>that the actual number of articles available (at the instant of the
>group command being answered) can be anything between (and
>including) 0 and the count returned.   Never mind...

As I have mentioned before, I am very much in favour of having the
first and last (low and high water marks) always returning valid
article numbers.  Otherwise, the wording looks good.  would a
'generates' versus 'accepts' tag help to depricate old versions?
    
>    The set of articles in a group may change after the GROUP command is
>    carried out. That is:
>[...]
>    * new articles may be added with article numbers greater than the
>    current high water mark (if an article that was the one with the
>    highest number has been removed, the next new article will not have
>    the number one greater than the current highwater mark).
>
>Don't use "current", that has temporal signifigance, and the
>"current" high water mark will change when a new article arrives
>(you just don't know it yet).  Use "the high water mark reported"
>or something like that.

There was one gent who said that he cached the information when the
group command was issued.  How would this affect your description here?
In that sense, current is kind of foggy, and having an indication of
significance might make the problem worse or better.

>    When a subsequent GROUP command for the same newsgroup is issued,
>    either by the same client or a different client, the current low
>    water mark in the response MUST be no less than that in any previous
>    response for that newsgroup.
>
>Again, this only applies if the group is not empty (or the 0 0 0)
>answer can be returned.

Agreed.  Once again, why is everyone a strong proponent of keeping 0 0 0 ?

>    3.1.2.  ARTICLE (selection by number)
>    
>    A previously valid article number might not remain valid if the article
>    has been removed. A previously invalid article number might become
>    valid if the article has been reinstated, but such an article number
>    MUST be no less than the current low water mark for that group.
>
>I'm not sure that it actually hurts a lot if the number goes back.
>if the client has marked to the low water mark as gone, then the
>reinstatement below it will never be noticed, and may as well never
>have happened for that client, but that is harmless.  Other clients
>may see it.

Agreed.  I think the point we need to address here is: what happens if
a client is keeping track of articles, the lwm goes above the article
and it is reinstated?  what happens if the client thinks it has read
the article (I fetched all of the articles that were there from 1 to
20, but did not get 13 as it was not there.  It is now reinstated.
How do I know that 13 has been reinstated and that I should look at it?)

Its coming along pretty good... as 'kre' suggested, but other
than that, it is starting to shape up.

regards,
Jack
-------------------------------------------------
Jack De Winter - Wildbear Consulting, Inc.
(519) 576-3873		http://www.wildbear.on.ca/

Author of SLMail(95/NT) (http://www.seattlelab.com/) and other great products.