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Re: Proposal: 205 Bodies [#88]

From: Roy T. Fielding <fielding@gbiv.com>
Date: Mon, 8 Jun 2009 12:30:57 +0200
Message-Id: <1C6155C7-B5E1-4E67-B343-5A9ACB90DB6A@gbiv.com>
Cc: HTTP Working Group <ietf-http-wg@w3.org>
To: Mark Nottingham <mnot@mnot.net>
On Jun 8, 2009, at 12:16 PM, Mark Nottingham wrote:

> <http://trac.tools.ietf.org/wg/httpbis/trac/ticket/88>
>> RFC2616 Section 4.3 "Message Body" enumerates those messages that  
>> don't include a message-body;
>>
>> All 1xx (informational), 204 (no content), and 304 (not modified)  
>> responses MUST NOT include a message-body. All other responses do  
>> include a message-body, although it MAY be of zero length.
>>
>> However, it does not list 205 (section 10.2.6).
>>
>> Also if you look at the texts for 204, 304 and 205 responses, you  
>> see that 204 and 304 say "MUST NOT include a message-body",  
>> whereas 205 says "MUST NOT include an entity". 204 and 304 go on  
>> to say that the message is terminated at the first empty line, but  
>> 205 does not say that.
>>
>
>
> Proposal:
>
>  - Add 205 to p1 sections 4.3 and 4.4 (which is where 2616's 4.3  
> ended up), and
>  - Revise the language in p2 8.2.6 (the definition of 205 Reset  
> Content) to use the "MUST NOT include a message-body".
>
> The only argument I can see against this is that someone might  
> include entity headers in a 205 response, in the belief that that  
> response updates a cache. This could be fixed by adding the phrase  
> "or entity headers" to the MUST NOT requirement above. However, I  
> would note that 204 doesn't have any such language, and this  
> confusion hasn't come up before, so I don't think it's really  
> necessary.
>
> I think this is *almost* editorial -- any objection?

Big objection.  205 was added late in the process of 2068 and
could not be grandfathered into the message parsing algorithm
as yet another (bad) exception.  The requirement that 205 not
include an entity means that the message-body MUST be of zero size
(i.e., Content-Length must be supplied with a value of 0
or Transfer-Encoding chunked is used with a zero-length chunk).

Hence, it is correct as specified, albeit confusing.  It will
be less confusing when the terminology is cleaned up.

....Roy
Received on Monday, 8 June 2009 10:31:30 GMT

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