Re: [squid-users] ETag support for html files

Henrik,

Thanks for your prompt response.

My comments/additional questions are embedded with >>SK.

Thanks,

Steve.

On Fri, 02 Jun 2006 11:10:41 +0200
  Henrik Nordstrom <henrik@henriknordstrom.net> wrote:
> tor 2006-06-01 klockan 13:43 -0400 skrev
>sknipe@tucows.com:
>
>> However, our html pages may change in the expires time
>> frame.
>
> Then you need to advertise a smaller expires interval or
>use
> "Cache-Control: max-age=XXX" to tell caches they must
>validate the
> page..
>
>> Perhaps a better model for us is more of an update based
>> model using ETag. The down side of this is that our
>> infrastructure is hit for each request. However, the hit
>> is minimal if the html page has not changed.
>
> In this scenario ETag just allows for a stronger
>"If-Modified-Since". In
> terms of caching of simple responses (no Vary) there is
>not much
> difference if you use the ETag or Last-Modified. And
>with both you need
> to set freshness appropriately to have the page
>revalidated with the
> frequency you need.
>
>
>> Also, I noticed that Squid forces http communication
>>into
>> http 1.0 mode. This has a negative effect when working
>> with IE and the ETag model. Can we have Squid interact
>>in
>> http 1.1?

>>SK The following HTTP response is generated by squid for IE.

Response Header IE:

(Status-Line) HTTP/1.0 200 OK (Please note the HTTP/1.0)

Response Header FireFox:

(Status Line) HTTP/1.x 200 OK (The 1.x works fine.)

In this case, IE will not send back the if-none-match with
the appropriate ETag.

Could you please verify the following. When ETag is used
for .html pages, the caching seems to be at the Browser
level. Does Squid play a role in the if-none-match with
ETags?

Is there a way to have an HTTP/1.1 or HTTP/1.x response
generated for IE?

Thanks very much,

Steve.

>
> Can you please elaborate on what negative effects is
>seen with IE here..
>
>> For the image, css and js files, we have a requirement
>>to
>> check if users are authorized to files before they are
>> serviced. Therefore, once cached in Squid they are
>> serviced by Squid and do not interface with our
>> infrastructure. Is there a mechanism in Squid to enable
>> the appropriate authorization checks before servicing?
>
> "Cache-Control: s-maxage=0" forces shared caches to
>revalidate the
> request with the origin server on every request.
>
>
> Please note that there generally is not much benefit to
>cache smallish
> objects (<10KB or so) which needs to be revalidated. The
>main benefit of
> caching small objects is the latency improvements, and
>these are almost
> completely lost if the object needs to be revalidated..
>
> Regards
> Henrik
Received on Fri Jun 02 2006 - 11:10:46 MDT