chl at clerew.man.ac.uk
Fri Jun 6 02:57:13 PDT 2003
In <Pine.LNX.4.44.0306051820560.4175-100000 at puck.litech.org> "Jeffrey M. Vinocur" <jeff at litech.org> writes:
>I think I've gotten everyone confused by me talking about my ideal version
>of this extension (if we didn't have existing implementations) and the
>present draft at the same time. Starting over from scrach, yes, I'd like
>more response codes. I don't think we can do anything useful now, though,
>unless we want to provide a different MODE that would result in new
>commands (or CHECK/TAKETHIS with additional return codes, I guess). Seems
>like more trouble than it's worth though -- servers that would run into
>the only practical problem I can think of (below) can be manually
>configured to a desired behavior by out-of-band communication between
But suppose existing practice is to return some code 4ab in some
situation, and existing implementations generate that (and others
understand it). Now suppose we want to divide that situation into two
sub-situations, one continuing to return 4ab, and the other returning 5ab.
Existing implementations will continue to send 4ab for both, but new ones
will start to send 5ab as well.
Will old clients be confused by seeing 5ab that they did not expect? It
depends. They will doubtless interpret any unknown 5xx as "go away, I
don't want to do that". If that is acceptable in the interim, then there
is no harm done in making the change. But I could well imagine other
situations where such a change would be harmful, and then we should not do
Bear in mind that we are not upgrading an existing standard here. We are
trying AUIU to codify a behaviour that has grown up informally. In that
sort of situation one may be able to be a bit more ruthless.
Charles H. Lindsey ---------At Home, doing my own thing------------------------
Tel: +44 161 436 6131 Fax: +44 161 436 6133 Web: http://www.cs.man.ac.uk/~chl
Email: chl at clerew.man.ac.uk Snail: 5 Clerewood Ave, CHEADLE, SK8 3JU, U.K.
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