Re: [squid-users] ICAP Processing Times

From: Marcus Kool <marcus.kool_at_urlfilterdb.com>
Date: Fri, 27 Jan 2012 15:09:21 -0200

The ICAP protocol does not stream in the sense that it forwards piece by piece.
The ICAP protocol only supports a preview which for Squid has a maximum of 64 KB.
So a large file with preview mode enabled, can send a configurable size
(between 1 byte and 64 KB) of the first part of the content to the ICAP server.
The ICAP server can say OK or SEND-THE-WHOLE-CONTENT.

So if you like watching movies from YouTube you need to configure the ICAP server
to enable preview and set the preview size to less than 64 KB. Hopefully
your ICAP server will respond with an "OK" to the preview and then Squid streams
the whole video directly to the browser bypassing the ICAP server.

Marcus

Justin Lawler wrote:
> Hi,
>
> We are just examining performance of our ICAP server - we were trying to determine for ICAP RESPMODs how squid behaves:
> 1) does squid stream the response over an ICAP connection as soon as it starts to receive the response?
> 2) does squid wait until its received the entire response before it starts to send the response over ICAP RESPMOD?
>
> While the first streaming method could potentially be faster - it could also hold up resources on the ICAP server for longer, especially if the remote response was slow - which is a concern. It would also make the logged response times on our ICAP server not be representative of the performance.
>
> Thanks and regards,
> Justin
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>
>
Received on Fri Jan 27 2012 - 17:09:27 MST

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