[NNTP] Snapshot 6

[Clive D.W. Feather]

Russ Allbery said:
> I'm still unhappy with the modifiers for a different reason, though,
> namely that it doesn't seem to me like it adds that much useful
> information to a client unless we make them mandatory (which I think we're
> agreed on not doing).

Yes, we're agreed on not doing it. At least, not in this round of things;
the requirements on clients are simply not to barf on them.

> If something like:
> 
>     AUTHINFO SASL
>     -480 READER POST
> 
> is there, then the client knows it *might* be able to post after
> authenticating, but still doesn't know if it actually will be able to post
> afterwards since it's going to depend on the credentials presented.

Right, but it also says "if you want to post, you need to authenticate
first" (and "SASL authentication is available"). In particular, if the
client doesn't have credentials to present, it knows it can't post.

> If
> this line isn't there and the server just says:
> 
>     AUTHINFO SASL
>     READER LISTGROUP
> 
> then the client doesn't know for certain that authentication *won't* help,
> since the server may just not be using modifiers.

True. Which means the client has to fall back to "suck it and see"; the
whole point of capabilities was to get rid of that, surely?

I gree that, so long as they're not mandatory, clients have to fall back to
heuristics. But I see this as something that will encourage the use of
modifiers; by your logic, I could claim that there's no point in having
CAPABILITIES at all because the server can always implement a command
without listing it in the output.

> I'm not really sure how I'd use these capabilities as a client even if I
> wanted to.  Clive, could you possibly sketch out how you anticipate a
> client using those capabilities to make decisions?

I'll try, but I don't have time this minute.

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