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Re: Idempotent partial updates

From: Julian Reschke <julian.reschke@gmx.de>
Date: Tue, 28 Feb 2012 11:19:41 +0100
Message-ID: <4F4CAA3D.7030200@gmx.de>
To: Mike Kelly <mikekelly321@gmail.com>
CC: "Eric J. Bowman" <eric@bisonsystems.net>, Martin Thomson <martin.thomson@gmail.com>, HTTP Working Group <ietf-http-wg@w3.org>
On 2012-02-28 11:10, Mike Kelly wrote:
> On Tue, Feb 28, 2012 at 5:27 AM, Eric J. Bowman<eric@bisonsystems.net>  wrote:
>> Martin Thomson wrote:
>>>
>>> I agree with Mike that PATCH (or a special POST) aren't visibly
>>> idempotent, which is a crucial characteristic if this is going to
>>> work.
>>>
>>
>> If 99.9% of partial updates are non-idempotent, wouldn't the need for
>> idempotent partial update be an edge case, as opposed to crucial?
>>
>> What we're trying to make visible on the wire is *sender intent* not
>> idempotency.  The sender doesn't intend to make idempotent vs. non-
>> idempotent requests.  Idempotency is a property of the request method,
>> not a sender intent in and of itself.
>
> No. What we should be trying to make visible "on the wire" are
> properties of a request that are useful/valuable for intermediate
> processing.
>
> The idempotency of a request is valuable for intermediate processing,
> because infrastructure can be developed to re-issue a client request
> on network failure.
>
> Having a request guaranteed to be non-partial is not useful or
> valuable for intermediate processing, apparently there are no examples
> of intermediary mechanisms which leverage this.

Just because something isn't useful to intermediaries (with which I 
don't fully agree) doesn't mean it isn't useful to be defined.

Best regards, Julian
Received on Tuesday, 28 February 2012 10:20:19 GMT

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