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Re: Zero-edits Counter Proposal for Issues 1 and 2 (Ping)

From: Julian Reschke <julian.reschke@gmx.de>
Date: Wed, 17 Feb 2010 22:31:51 +0100
Message-ID: <4B7C6047.1020402@gmx.de>
To: Maciej Stachowiak <mjs@apple.com>
CC: "Tab Atkins Jr." <jackalmage@gmail.com>, public-html@w3.org
On 17.02.2010 22:17, Maciej Stachowiak wrote:
>
> On Feb 17, 2010, at 7:41 AM, Julian Reschke wrote:
>
>> On 17.02.2010 16:30, Tab Atkins Jr. wrote:
>>
>>> ..
>>> It's possible that we could define a new method for @ping, call it
>>> PING. It would still be "unsafe", that is, not idempotent, by
>>> definition. I'm not sure what possible benefits this could bring over
>>> just using POST, though.
>>> ...
>>
>> "safe" and "idempotent" are different things.
>
> Aren't all "safe" methods also "idempotent" by definition?

Almost.

Except for the side effects that a safe method is allowed to have, such 
incrementing hit counters etc.:

"Naturally, it is not possible to ensure that the server does not 
generate side-effects as a result of performing a GET request; in fact, 
some dynamic resources consider that a feature. The important 
distinction here is that the user did not request the side-effects, so 
therefore cannot be held accountable for them."

If you ignore those potential side effects as self-inflicted by the 
server (and not requested by the user), then yes, a safe method is also 
idempotent.

Best regards, Julian
Received on Wednesday, 17 February 2010 21:33:17 UTC

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