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Re: Please evaluate my cache-control & pragma etc. code [message #182522 is a reply to message #182518]

Sat, 10 August 2013 08:49

The Natural Philosoph
Messages: 993
Registered: September 2010

Karma:

Senior Member

On 09/08/13 19:22, Twayne wrote:
> Mainly I'm interested in whether it's considered workable/usable.
> It doesn't seem to be working on my win 7 XAMPP PHP5.3 Local
> Server. The data still seems to exist if/when I "go back" to the
> preceding page of an e-mail form.
>
> <?php
> session_start();
> header('Cache-Control: no-cache, no-store, must-revalidate'); //HTTP/1.1
> header('Expires: Sun, 01 Jul 2005 00:00:00 GMT');
> header('Pragma: no-cache'); //HTTP/1.0
>
> TIA,
>
> Twayne`
>
my limited experience suggests that browser caching is more affected by
the etag.
I have been writing a framework that serves all pages /objects from a
database ( for reasons of security and control), and found that in
general browsers don't really honor cache control, but they do honor etags.
I think proxies tend to honor cxahche control more.

The browsers tend to say 'ive got a copy, do I need a new one?' and
actually ask, using the etag.

I found that out looking at my log files on pages with multiple images
under constant rerfreshing. The logs were full of 304 responses, but
there were always as many of those as the page had images for a given
page load.

The code that checks the etag is here - it really does reduce server
load if you want to not resend data that's already been sent

// check if etag matches if none match request headers
function check_etag($etag)
{
if(isset($_SERVER['HTTP_IF_NONE_MATCH']) &&
strstr($_SERVER['HTTP_IF_NONE_MATCH'],$etag))
{
header('HTTP/1.0 304 Not Modified');
exit();
}
}
This is a handy way to encourage browsers not to re-download static pages.

--
Ineptocracy

(in-ep-toc’-ra-cy) – a system of government where the least capable to lead are elected by the least capable of producing, and where the members of society least likely to sustain themselves or succeed, are rewarded with goods and services paid for by the confiscated wealth of a diminishing number of producers.

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[Message index]

		Please evaluate my cache-control & pragma etc. code By: bill on Fri, 09 August 2013 18:22
		Re: Please evaluate my cache-control & pragma etc. code By: J.O. Aho on Fri, 09 August 2013 20:57
		Re: Please evaluate my cache-control & pragma etc. code By: bill on Fri, 09 August 2013 23:12
		Re: Please evaluate my cache-control & pragma etc. code By: The Natural Philosoph on Sat, 10 August 2013 08:49
		Re: Please evaluate my cache-control & pragma etc. code By: bill on Sat, 10 August 2013 17:21
		Re: Please evaluate my cache-control & pragma etc. code By: Fiver on Sat, 10 August 2013 15:19
		Re: Please evaluate my cache-control & pragma etc. code By: bill on Sat, 10 August 2013 17:17

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