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Re: HTTP Connection Management (draft-ietf-http-connection-00.txt)

From: Donald Neal <d.neal@waikato.ac.nz>
Date: Thu, 27 Mar 1997 11:45:50 +1200
Message-Id: <>
To: http-wg@cuckoo.hpl.hp.com
X-Mailing-List: <http-wg@cuckoo.hpl.hp.com> archive/latest/2922
At 01:11 PM 26/03/97 -0800, David W. Morris wrote:
>On Wed, 26 Mar 1997, Jeff de la Beaujardiere wrote:
>> Because resources on the web are typically document-like units comprising
>> HTML and several inline entities like images and scripts, it would seem
>> useful for the server to send a close-connection hint to the client when
>> server has transmitted, and received ACKs for, all of the content in the
>> current "page."  Presumably the user will spend enough time perusing the
>> document that the benefits of maintaining the connection will have
>> diminished to the point of negligibility.  Of course, the client may
>> (indeed, should) delay acting on the hint for 10-60 sec in case the user
>> immediately follows an anchor to another document on the server.
>The server generally won't know when the client is finished. The client
>may obtain some resources from caches, for example.  Futhermore, for the
>server to know it would have to parse the content. A to be heavily
>discouraged requirement. The client knows when it has the full page worth
>of stuff.

  What the client knows may well depend on what the client is. If the
client is itself a large caching server, it does not know how long it will
be before the end user on whose behalf it is retrieving information will
ask for another object from the same server. An entirely different
question, to which it does not know the answer either, is how long it will
be before any of its clients ask it for material from the same server.
  However, even in the case where the client does not know these things, it
is quite conceivable that such a caching server will make use of its own
algorithm, based on things like time since last request for an object from
the server and round-trip time to the server, to work out how long it
wishes to retain an existing TCP connection, and that it will choose to
ignore any hints it may receive. And the information on which that decision
is based is very unlikely to be available to the server.
- Donald Neal
Received on Wednesday, 26 March 1997 16:01:07 UTC

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