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Re: Persistent connections - timeout policies -Forwarded

From: Henrik Frystyk Nielsen <frystyk@w3.org>
Date: Sun, 30 May 1999 12:38:39 -0400
Message-Id: <>
To: danielh@econ.ag.gov, www-talk@w3.org
At 18:54 29/05/1999 -0400, danielh@econ.ag.gov wrote:

>Given that one might expect a major use of a maintained connection to be
>retrieval of inlined images, and since the user-agent has to parse the 
>html document before knowing what images to request, it seems that the
>"pipeline" method is less useful (although a second connection, with
>multiple requests for various images could be used..)

Note that the client doesn't have to parse the *whole* document before
issuing new requests - often there are enough links embedded in the first
chunks of HTML to enable the client to submit new pipelined requests almost

You can see a more detailed explanation of the potential benefits of
pipelining in our sigcomm paper:


Paul Barford also has a very interesting paper on pipelining but I don't
have a link handy.

>>If a timeout system is used should the server send a response and
>>Connection: close header before it closes the connection?
>>Even though there might not be a request to respond to?

>That strikes me as unnecessary. a maintain-connection capable browser
>should be smart enough to know when to give up, but may not be smart
>enough to know what to do with a unsolicited response.

No unsolicited response - the client is interested in dropping the
connection when it is done because having the server closing the connection
may force the client to recover a pipeline. The server can always drop the
idle connection when low on resources.

Henrik Frystyk Nielsen,
World Wide Web Consortium
Received on Monday, 31 May 1999 13:12:46 UTC

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