Multiple Choices for Web Statistics
      Multiple Choices for Web Statistics:
      
      <a href=stats.tables.html>Version with HTML tables
      
      <a href=stats.html>Version without HTML tables
      
      <a href=stats.ps>Postscript version
      
      blex

   The Alternates header in the above script must be read as a single
   line.  The script always generates a list response with the 200 (OK)
   code, which ensures compatibility with non-negotiating HTTP/1.0
   agents.








 
RFC 2295            Transparent Content Negotiation           March 1998


21.2 Direct support by HTTP servers

   Sophisticated HTTP servers could make a transparent negotiation
   module available to content authors.  Such a module could incorporate
   a remote variant selection algorithm and an implementation of the
   algorithm for generating choice responses (section 10.2).  The
   definition of interfaces to such modules is beyond the scope of this
   specification.

21.3 Web publishing tools

   Web publishing tools could automatically generate several variants of
   a document (for example the original TeX version, a HTML version with
   tables, a HTML version without tables, and a Postscript version),
   together with an appropriate variant list in the interface format of
   a HTTP server transparent negotiation module.  This would allow
   documents to be published as transparently negotiable resources.

22 Appendix: Example of choice response construction

   The following is an example of the construction of a choice response
   by a proxy cache which supports HTTP/1.1 and transparent content
   negotiation.  The use of the HTTP/1.1 conditional request mechanisms
   is also shown.

   Assume that a user agent has cached a variant list with the validator
   "1234" for the negotiable resource http://x.org/paper.  Also assume
   that it has cached responses from two neighboring variants, with the
   entity tags "gonkyyyy" and W/"a;b".  Assume that all three user agent
   cache entries are stale: they would need to be revalidated before the
   user agent can use them.  If http://x.org/paper accessed in this
   situation, the user agent could send the following request to its
   proxy cache:

     GET /paper HTTP/1.1
     Host: x.org
     User-Agent: WuxtaWeb/2.4
     Negotiate: 1.0
     Accept: text/html, application/postscript;q=0.4, */*
     Accept-Language: en
     If-None-Match: "gonkyyyy;1234", W/"a;b;1234"

   Assume that the proxy cache has cached the same three items as the
   user agent, but that it has revalidated the variant list 8000 seconds
   ago, so that the list is still fresh for the proxy.  This means that
   the proxy can run a remote variant selection algorithm on the list
   and the incoming request.





 
RFC 2295            Transparent Content Negotiation           March 1998


   Assume that the remote algorithm is able to choose paper.html.en as
   the best variant.  The proxy can now construct a choice response,
   using the algorithm in section 10.2.  In steps 1 and 2 of the
   algorithm, the proxy can construct the following conditional request
   on the best variant, and send it to the origin server:

     GET /paper.html.en HTTP/1.1
     Host: x.org
     User-Agent: WuxtaWeb/2.4
     Negotiate: 1.0
     Accept: text/html, application/postscript;q=0.4, */*
     Accept-Language: en
     If-None-Match: "gonkyyyy", W/"a;b"
     Via: 1.1 fred

   On receipt of the response