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Re: Idempotent partial updates

From: Julian Reschke <julian.reschke@gmx.de>
Date: Mon, 27 Feb 2012 16:15:07 +0100
Message-ID: <4F4B9DFB.4040903@gmx.de>
To: Mike Kelly <mikekelly321@gmail.com>
CC: HTTP Working Group <ietf-http-wg@w3.org>
On 2012-02-27 15:18, Mike Kelly wrote:
> Hi all,
> HTTPbis has amended the semantics of PUT to be unambiguous in its

"clarified", not "amended". The point being: PUT never allowed partial 
updates. Because people used if for partial updates anyway, we made that 
part clearer.

> prevention of partial updates. I cannot understand the rationale
> behind this change, and I have a couple of questions for the group:
> - Given that 2616 was ambiguous, is it acknowledged that this
> represents a breaking change to any existing infrastructure that
> relies on PUT requests that are permitted to be partial?

I don't think it ever was ambiguous.

"The PUT method requests that the enclosed entity be stored under the 
supplied Request-URI."

> - How is it foreseen that this over-specification of PUT will benefit
> the web? i.e. what infrastructure will be able to exist once all PUT
> requests are unambiguously non-partial?

I don't think it's an over-specification. And even if it was, it's not new.

> - Is it acknowledged that this change will effectively prevent proper
> idempotent partial updates on the web?

No. You can do idempotent partial updates with POST and PATCH (by 
including an If-Match header field).

> - In light of the recent proliferation of 'mobile clients' which
> operate on relatively slow and unreliable networks where partial
> idempotent updates would be ideal; is the loss of idempotent partial
> updates considered acceptable?

See above: (1) PUT never allowed partial updates, and (2) you don't need 
PUT to make modifications idempotent.

Best regards, Julian
Received on Monday, 27 February 2012 15:15:50 UTC

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