[NNTP] [2505] CAPABILITIES indication of features not currently available

Clive D.W. Feather clive at demon.net
Tue Nov 30 01:51:10 PST 2004


Issue: do we provide a way for CAPABILITIES to advertise features that
aren't available right now but could be, or have been.

Ken Murchison said:
> 2505:  I thought we had already decided that all of this "negative 
> capability" business was too much.  I'm opposed to this proposal.

It came back again in at least one of Russ's messages.

The reason for proposing it is that it addresses a number of issues:
* advertising "can only authenticate after TLS", "can do more SASL options
  with TLS", "can only authenticate after MODE READER", and so on;
* indicating the authentication methods that were available after
  successful SASL;
* indicating that the server is mode-switching;
and so on. Now we can come up with ad-hoc solutions for each of those, but
isn't it better to have a framework for it?

In particular, the present SASL stuff is an abomination - advertising a
capability as available with the secret understanding that that means it
*isn't* available - and goes directly against a MUST in the core
specification.

What is the objection to this? If it's the detail of the "-", "--", "-480"
stuff, then I'm happy to amend or drop that part. But what is wrong with
the basic principle of having a consistent way of saying "extension X wishes
to tell you that capability Y isn't currently available"?

-- 
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            |                            |



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