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Re: Our old friends, weak ETags

From: Julian Reschke <julian.reschke@gmx.de>
Date: Fri, 20 Jul 2012 09:55:21 +0200
Message-ID: <50090EE9.7010304@gmx.de>
To: Bruce Perens <bruce@perens.com>
CC: ietf-http-wg@w3.org
On 2012-07-20 07:08, Bruce Perens wrote:
> Hi Adrien,
>
> I use ETag because of an insufficiency in RFC 2616 dates: their
> resolution is one second. Updates to entities at sub-second intervals
> are possible and would result in entities with the same Last-Modified
> date. To be pedantically resolution-independent, I convert the date/time
> to a string representation of a ratio. It's presently the number of
> nanoseconds since the epoch. I encode that and an entity serial number
> in the ETag.
>
> If HTTP dates are extended to have sub-second resolution, I will
> probably be able to do without ETags.

That explains the choice of ETags, but not necessarily *weak* ETags.

(I think Apache httpd uses weak etags if it can't get a sub-second 
timestamp from the file system)

Best regards, Julian
Received on Friday, 20 July 2012 07:56:15 GMT

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