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Re: (ACCEPT*) Consensus

From: Koen Holtman <koen@win.tue.nl>
Date: Mon, 15 Apr 1996 21:43:02 +0200 (MET DST)
Message-Id: <199604151943.VAA17491@wsooti05.win.tue.nl>
To: "Roy T. Fielding" <fielding@avron.ICS.UCI.EDU>
Cc: koen@win.tue.nl, http-wg%cuckoo.hpl.hp.com@hplb.hpl.hp.com
Roy T. Fielding:
>
>> The old 1.1-01 draft required 406 responses to contain `a list of
>> resource characteristics and locations from which the user or user
>> agent can choose the one most appropriate.'  Such a thing is not
>> required in the 416 response I defined, so I thought it best to assign
>> a new code, rather than rewrite the 406 text.
>
>That would be incorrect -- the 416 response would still require some
>message in the response as a fall-back to older clients (or simply
>as more information).

Don't get me wrong, I completely agree that a `not acceptable'
response must include _some_ error message as an entity.  What I did
in my text for 416 is getting rid of the requirement that this error
message contains `a list of resource characteristics and locations
from which the user or user agent can choose the one most
appropriate'.

The `you have to send along a list with appropriate alternatives'
requirement in the 1.1-00 draft means that you can only send a 406
response if you indeed have appropriate alternatives.

But for the majority of URLs, there are no other alternative versions,
the only one you have is the one you just found to be unacceptable.
A resource
  http://blah.com/bla.mpeg
for which there is no alternative representation available cannot send
a 406 error under the 1.1-00 draft.  That is why I defined a new error
code, 416, for it to use.

>What you describe is exactly what 406 is intended to do, so use it.

You may have intended 406 to be used like this, but the language in
the old spec did not allow 406 to be used in this way by plain
resources.

>Rewrite whatever text no longer applies, but do not introduce a new
>error code.  There do not exist any implementations that depend on
>draft 01's description of 406 (not that it would matter, since the
>description is essentially the same even after your changes).

I guess this means you want me to swap 406 and 416, because 416 is my
rewritten 604.  OK, I have no problems with that.

> ...Roy T. Fielding

Koen.
Received on Monday, 15 April 1996 12:52:46 EDT

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