[NNTP] Extension docs snapshots

[Clive D.W. Feather]

Ken Murchison said:
>> The argument for MODE READER is that it invokes an entire new application.
>> But, as I understand it, MODE STREAM merely confirms that the other two
>> commands in the extension are implemented.
> That's my understanding, but do we know for sure that some 
> implementations don't fork a new app (or convolute itself in some other 
> way) for MODE STREAM?

I'd be surprised, because they still need to accept IHAVE in both states.

Andrew? Russ?

> Even if the client is just probing the server to see if it can do 
> CHECK/TAKETHIS, isn't the friendly thing to wait until the server says 
> "yea" or "nea" before trying the command?

There's a difference between "friendly thing" and "must do it this way".
I dislike forbidding things without a good reason.

> Obviously the server can just 
> return 501/503 (which ever is appropriate) to CHECK if pipelined but 
> unsupported.

500, actually.

> As an aside, I notice that LIST EXTENSIONS is allowed to be pipelined 
> (its not prohibited in -25).  Shouldn't we encourage friendly behavior 
> and not allow it to be pipelined (at least not with optional 
> commands/extensions)?

LIST EXTENSIONS is not permitted to alter the server state, and it MUST be
possible to use extensions without executing it. So there's no reason to
forbid pipelining. On the contrary, a client might well want to pipeline
(say) LIST EXTENSIONS, DATE, and NEWGROUPS before deciding what further
commands to execute.

I really don't see forbidding pipelining as "friendly behaviour"; I see it
as most unfriendly, and only to be done where absolutely necessary.

> Either way, MODE STREAM should probably be 
> consistent with LIST EXTENSIONS since its essentially a capability 
> discovery command.

Agreed.

-- 
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            |                            |