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Fwd: Our old friends, weak ETags

From: Mark Nottingham <mnot@mnot.net>
Date: Fri, 20 Jul 2012 15:25:04 +1000
To: HTTP Working Group <ietf-http-wg@w3.org>
Message-Id: <1A5726B2-376F-4C64-8F87-936C928A8224@mnot.net>
Bruce Perens isn't on the mailing list, so forwarding (a dup may occur when W3C staff see it):

Begin forwarded message:
> 
> 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.
> 
>    Thanks
> 
>    Bruce
> 

--
Mark Nottingham   Systems Architect, Cloud Standards and APIs
mark.nottingham@rackspace.com    http://www.mnot.net/

--
Mark Nottingham   http://www.mnot.net/
Received on Friday, 20 July 2012 05:25:32 GMT

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