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Re: i19 Bodies on GET (and other) requests

From: Mark Nottingham <mnot@mnot.net>
Date: Wed, 17 Jan 2007 15:25:06 +1100
Message-Id: <60325577-F3CF-4D3D-9793-38255A306064@mnot.net>
Cc: "ietf-http-wg@w3.org Group" <ietf-http-wg@w3.org>
To: Roy T. Fielding <fielding@gbiv.com>

On 2007/01/17, at 1:52 PM, Roy T. Fielding wrote:

> On Jan 16, 2007, at 6:09 PM, Mark Nottingham wrote:
>> Are you saying that a cache on such a proxy or gateway SHOULD NOT  
>> return a fresh response from cache, but instead forward the  
>> request, if a GET request has a message-body?
> No.  A cache does not "return" and does not "forward".  You aren't  
> using
> the definitions as stated in the specification.
>    cache
>       A program's local store of response messages and the subsystem
>       that controls its message storage, retrieval, and deletion. A
>       cache stores cacheable responses in order to reduce the response
>       time and network bandwidth consumption on future, equivalent
>       requests. Any client or server may include a cache, though a  
> cache
>       cannot be used by a server that is acting as a tunnel.
> You are assuming that a cache is a server because that is how the term
> is often used in our line of work.  That is fairly common, and you are
> right that 2616 has several places where the word cache is misused.

I'm aware of the distinction, just lacking distinct terminology to  
describe the cache's behaviour with.

> What I suggested was:
>   When a request message contains both a message-body of non-zero
>   length and a method that does not define any semantics for that
>   request message-body, then an origin server SHOULD either ignore
>   the message-body or respond with an appropriate error message
>   (e.g., 413).  A proxy or gateway, when presented the same request,
>   SHOULD either forward the request inbound with the message-body or
>   ignore the message-body when determining a response.
> Note that a proxy or gateway "SHOULD either forward ... or ignore".
> That entirely covers all possible combinations of server, with or
> without cache, and without the contradictions that were added to 2616.
> When a proxy or gateway uses a cache, it is "determining a response".
> We could add "determining a response though use of an internal
> cache and/or configurable error mechanism", but then we would be
> making a guess about the scope of ways in which a proxy or gateway
> might be implemented, rather than specifying an HTTP interface
> requirement.

Works for me.

Mark Nottingham     http://www.mnot.net/
Received on Wednesday, 17 January 2007 04:25:01 UTC

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