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Re: Improving If-Modified-Since

From: Lou Montulli <montulli@mozilla.com>
Date: Tue, 15 Aug 95 13:04:40 -0700
Message-Id: <3030FDD8.167E@mozilla.com>
To: Roy Fielding <fielding@beach.w3.org>
Cc: http-wg%cuckoo.hpl.hp.com@hplb.hpl.hp.com
> >In addition to supporting size=SIZE I encourage other server authors to
> >do an _equals_ comparison rather than a greater than or equal comparison
> >of the two dates.
> 
> Absolutely not -- that would be a violation of both the spec and the
> intentions of IMS.  In addition to being a cache mechanism, it allows
> a client to request a document "only if it has been changed in the last
> fifteen minutes".  In this case, it may not know what the server's
> Last-Modified date is prior to the request.

If it is a violation of the spec then you really ought to make the spec
clearer on this point.  All the major servers that I know of do a
greater than or equal comparison.  The spec needs to be changed to
specifically say that 304 should only be returned when the If-modified-since
date matches the current modification date of the file.

:lou
-- 
Lou Montulli                 http://www.mcom.com/people/montulli/
       Netscape Communications Corp.
Received on Tuesday, 15 August 1995 13:06:16 EDT

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