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Re: If-Modified-Since No Longer Cool?

From: Dave Kristol <dmk@research.bell-labs.com>
Date: Tue, 8 Oct 96 09:32:31 EDT
Message-Id: <9610081332.AA29941@aleatory>
To: luotonen@netscape.com
Cc: www-talk@w3.org
Ari Luotonen <luotonen@netscape.com> wrote:

  > Use the time string given by the Last-modified date.  The comparison
  > is (as per the HTTP spec) an equality-check, not a less-than-or-equal.

The comparison in Netscape's servers may be an equality check, but that
is most certainly not what the HTTP spec. calls for:

    14.24 If-Modified-Since

    The If-Modified-Since request-header field is used with the GET method
    to make it conditional: if the requested variant has not been modified
    since the time specified in this field, an entity will not be returned
    from the server; instead, a 304 (not modified) response will be returned
    without any message-body.
    [...]
    Note that if a client uses an arbitrary date in the If-Modified-Since
    header instead of a date taken from the Last-Modified header for the
    same request, the client should be aware of the fact that this date is
    interpreted in the server's understanding of time....

In short, the server should interpret the I-M-S header, not just do a
string compare.

Dave Kristol
Received on Tuesday, 8 October 1996 09:35:37 GMT

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