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(HOST) (FULLURL) draft of changes for W.G. review.

From: <jg@w3.org>
Date: Fri, 29 Mar 96 18:10:02 -0500
Message-Id: <9603292310.AA22311@zorch.w3.org>
To: http-wg%cuckoo.hpl.hp.com@hplb.hpl.hp.com
Cc: klensin@mail1.reston.mci.net
To Roy's rewrite of 10.22 Host he circulated a while back (which looks pretty
good to me), I've added a few other sentences in other sections, 
and drafted a section to the Changes from HTTP/1.0 appendix.
This also resolves the FULLURL issue, so that we have a transition plan
to full URL's in some future HTTP version.

I believe this issue has been talked to death, so now is the time to
complain about exact wording and/or nits.  We must get this one so that no fool can
misunderstand it.
				- Jim Gettys


Add to section 5.1.2 Request-URI
   To allow for transition to absoluteURI's in all requests in future versions
   of HTTP, HTTP/1.1 servers must accept the absoluteURI form in requests, 
   even though HTTP/1.1 clients will not likely normally generate them.
   Later HTTP versions (beyond HTTP 1.1) may require absoluteURI's everywhere,
   once HTTP 1.0 clients and servers are no longer in service.

Change the sentence:
   The absoluteURI form is only allowed when the request is being made to
   a proxy.
To:
   The absoluteURI form is required when the request is being made to
   a proxy.  The absoluteURI form is only allowed to an origin server
   if the client knows the server supports HTTP/1.1 or later.


Add the following sentence to Section 8. Method Definitions:

   Note that the Host request-header field (Section 10.22) must accompany
   HTTP 1.1 requests.

Replace the current 10.22 with the following:

10.22  Host

   The Host request-header field specifies the Internet host and port
   number of the resource being requested, as obtained from the original
   http URL (Section 3.2.2) given by the user or referring resource.
   The Host field value must represent the network location of the
   origin server or gateway given by the original http URL.  This allows
   the origin server or gateway to differentiate between
   internally-ambiguous URLs (such as the root "/" URL of a server
   harboring multiple virtual hostnames).

       Host = "Host" ":" host [ ":" port ]    ; see Section 3.2.2

   A "host" without any trailing port information is equivalent to
   a value of "host:80".  For example, a request on the origin server
   for <http://www.w3.org/pub/WWW/> must include:

       GET /pub/WWW/ HTTP/1.1
       Host: www.w3.org

   The Host header field must be included in all HTTP/1.1 request
   messages on the Internet (i.e., on any message corresponding to a
   request for an http URL, as described in Section 3.2.2).  If the
   Host field is not already present, an HTTP/1.1 proxy must add a Host
   field to the request message prior to forwarding it on the Internet.
   If an HTTP/1.1 request message lacking a Host header field is
   received via the Internet by an origin server or gateway, that server
   must respond with a 400 status code.

			Note
   It is extremely important that HTTP/1.1 client implementations use the 
   Host request-headers and server implementations both accept absoluteURI's
   and also report errors if Host request-headers are not recieved with 
   HTTP/1.1 requests (see Appendix D.1).


Add to Appendix D (Chagnes from HTTP/1.0:

   D.1 Changes to Simplify Vanity Web Servers and Conserve IP Addresses

   The requirements on clients and servers to support the Host 
   request-header, report an error if the Host request-header is 
   missing from an HTTP/1.1 request (Section 10.22), 
   and accept absolute URI's (Section 5.1.2) are the most important 
   changes from HTTP/1.0.

   In HTTP/1.0 there is a one to one relationship of IP addresses and servers,
   as there is no other way to disambiguate the server of a request
   than the IP address of that request.
   This change to HTTP will allow the Internet, once HTTP/1.0
   clients and servers are no longer common, to support multiple Web sites 
   from a single IP address, greatly simplifying large operational Web 
   servers sites, where the routing of many IP addresses to a single 
   host has created serious problems.  The Internet will also be 
   able to recover the IP addresses that have been used for this purpose.
   Given the rate of growth of the Web, and the number of servers already
   deployed, it is extremely important that implementations of HTTP/1.1 
   correctly implement these requirements before deployment.
Received on Friday, 29 March 1996 15:16:32 EST

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