HTTP/1.1 304 Not Modified
     Date: Tue, 11 Jun 1996 20:05:31 GMT
     Etag: "gonkyyyy"

   from the origin server, the proxy can use its freshly revalidated
   paper.html.en cache entry to expand the response to a non-304
   response:

     HTTP/1.1 200 OK
     Date: Tue, 11 Jun 1996 20:05:31 GMT
     Content-Type: text/html
     Last-Modified: Mon, 10 Jun 1996 10:01:14 GMT
     Content-Length: 5327
     Cache-control: max-age=604800
     Etag: "gonkyyyy"
     Via: 1.1 fred
     Age: 0

     A paper about ....

   Using this 200 response, the proxy can construct a choice response
   in step 4 of the algorithm:

     HTTP/1.1 200 OK
     Date: Tue, 11 Jun 1996 20:05:31 GMT
     TCN: choice
     Content-Type: text/html
     Last-Modified: Mon, 10 Jun 1996 10:01:14 GMT
     Content-Length: 5327
     Cache-control: max-age=604800
     Content-Location: paper.html.en




 
RFC 2295            Transparent Content Negotiation           March 1998


     Alternates: {"paper.html.en" 0.9 {type text/html} {language en}},
                 {"paper.html.fr" 0.7 {type text/html} {language fr}},
                 {"paper.ps.en"   1.0 {type application/postscript}
                     {language en}}

     Etag: "gonkyyyy;1234"
     Vary: negotiate, accept, accept-language
     Expires: Thu, 01 Jan 1980 00:00:00 GMT
     Via: 1.1 fred
     Age: 8000

     A paper about ....

   The choice response can subsequently be shortened to a 304 response,
   because of the If-None-Match header in the original request from the
   user agent.  Thus, the proxy can finally return

     HTTP/1.1 304 Not Modified
     Date: Tue, 11 Jun 1996 20:05:31 GMT
     Etag: "gonkyyyy;1234"
     Content-Location: paper.html.en
     Vary: negotiate, accept, accept-language
     Expires: Thu, 01 Jan 1980 00:00:00 GMT
     Via: 1.1 fred
     Age: 8000

   to the user agent.

























 
RFC 2295            Transparent Content Negotiation           March 1998


23 Full Copyright Statement

   Copyright (C) The Internet Society (1998).  All Rights Reserved.