If-Modified-Since and 304

luotonen@ptsun00.cern.ch (Ari Luotonen)
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Date: Thu, 10 Mar 1994 18:17:46 --100
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From: luotonen@ptsun00.cern.ch (Ari Luotonen)
To: Multiple recipients of list <www-talk@www0.cern.ch>
Subject: If-Modified-Since and 304
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I added If-Modified-Since: and 304 Use Local Copy to HTTP spec.
I also added 204 No Response that seemed to be missing from there.

If-Modified-Since: date
   This request header is used with GET method to make it conditional: if
   the requested document has not changed since the time specified in
   this field the document will not be sent, but instead a Use Local Copy
   304 reply.
   Format of this field is the same as for Date:.

   If the client has done a conditional GET and access is allowed, but
   the document has not been modified since the date and time specified
   in If-Modified-Since field, server responds with 304 status code, and
   does not send the document back to the client.
   This is to allow fast update of caches.
   Server has received the request but there is no information to send
   back, and the client should stay in the same document view. This is
   mainly to allow input for scripts without changing the document at the
   same time.

-- Cheers, Ari --