• Status: Solved
  • Priority: Medium
  • Security: Public
  • Views: 1486
  • Last Modified:

Add Expires Headers - PHP

Hi Experts,

Can you please tell me how to efficiently add expires headers to html elements please? gtmetrix.com is saying that expires headers are normally used with images but should also be used with all page componants including scripts, css and flash.

How can this be done? I'm using PHP if that helps.

Thank you
0
wilson1000
Asked:
wilson1000
2 Solutions
 
WabbitSeasonCommented:
You would normally add such headers by either configuring the webserver (for example using a .htaccess) or by serving the page components through PHP. The first method is preferred, as it doesn't require PHP to be loaded for every component. Have a look at http://www.askapache.com/htaccess/apache-speed-expires.html for an example using .htaccess.
0
 
svgmucCommented:
An Expires header is added to a document downloaded from a web server. This could be a html file, an image or any other kind of document file.

Expires headers can be configured in your web server by adding this line to your apache configuration or a .htaccess file:

ExpiresActive On
ExpiresByType image/gif "modification plus 5 hours 3 minutes"
ExpiresByType text/css "now plus 5 minutes"

Please see http://httpd.apache.org/docs/2.2/mod/mod_expires.html for documentation.

Also, since you mentioned PHP, you can send headers via PHP by adding this line to your code:

header("Expires: Tue, 24 Aug 2010 05:00:00 GMT");
0
 
wilson1000Author Commented:
Hi, thanks gentleman.

I have tried the PHP header() function but this is returning no results within the live web test so I'll pass this over to our backend developer for changes to server config.

I'll return soon!

Thanks again




0
Ultimate Tool Kit for Technology Solution Provider

Broken down into practical pointers and step-by-step instructions, the IT Service Excellence Tool Kit delivers expert advice for technology solution providers. Get your free copy now.

 
wilson1000Author Commented:
Hi, quick question...


@ svgmuc: How do we format the code for server config? I take it we remove the quotes ""?
0
 
wilson1000Author Commented:
Hey don't worry... I followed your link and found the resource at apache.
0
 
onemadeyeCommented:
I use this codes on my development :


<?php

header("Expires: Thu, 17 May 2001 10:17:17 GMT"); // Date in the past
header("Last-Modified: " . gmdate("D, d M Y H:i:s") . " GMT"); // always modified
header("Cache-Control: no-cache, must-revalidate"); // HTTP/1.1
header("Pragma: no-cache");

ob_start();

?>

Open in new window

0
 
wilson1000Author Commented:
I see what you're saying however, I need to instruct the user agent to cache a vast majority of files that we distribute with our page.

Your expires header looks to be initializing no cache at all.

As I said before, I've used the code below to no avail and would like the server to take care of this... running test now so will get back in a short time...

$expires = 60*60*24*14;
header("Pragma: public");
header("Cache-Control: maxage=".$expires);
header('Expires: ' . gmdate('D, d M Y H:i:s', time()+$expires) . ' GMT');

Open in new window

0
 
Ray PaseurCommented:
For the most part, the server should do all of this for you.  If you force a download, you probably do not want it to be cached.  You can use something like this to handle that "edge case."
<?php // RAY_force_download.php
error_reporting(E_ALL);


// A FILE TO DOWNLOAD - THIS LINK COULD COME IN THE URL VIA $_GET OR COULD BE GENERATED INSIDE THE SCRIPT
$url = "http://www.google.com/intl/en_ALL/images/logo.gif";

// USE CASE
force_download($url);


// FUNCTION TO FORCE A DOWNLOAD
function force_download($filename)
{
    // GET A NAME FOR THE FILE
    $basename = basename($filename);

    // GET THE CONTENTS OF THE FILE
    $filedata = file_get_contents($filename);

    if ($filedata)
    {
        // THESE HEADERS ARE USED ON ALL BROWSERS
        header("Content-Type: application-x/force-download");
        header("Content-Disposition: attachment; filename=\"$basename\"");
        header("Content-length: ".(string)(strlen($filedata)));
        header("Expires: ".gmdate("D, d M Y H:i:s", mktime(date("H")+2, date("i"), date("s"), date("m"), date("d"), date("Y")))." GMT");
        header("Last-Modified: ".gmdate("D, d M Y H:i:s")." GMT");

        // THIS HEADER MUST BE OMITTED FOR IE 6+
        if (FALSE === strpos($_SERVER["HTTP_USER_AGENT"], 'MSIE '))
        {
            header("Cache-Control: no-cache, must-revalidate");
        }

        // THIS IS THE LAST HEADER
        header("Pragma: no-cache");

        // FLUSH THE HEADERS TO THE BROWSER
        flush();

        // CAPTURE THE FILE IN THE OUTPUT BUFFERS - WILL BE FLUSHED AT SCRIPT END
        ob_start();
        echo $filedata;
    }
}

Open in new window

0
 
wilson1000Author Commented:
Thank you,

I was only going to award points to @svgmuc for his direction as this is what I needed however, Ray offered a great solution to cover required downloads.

0
Question has a verified solution.

Are you are experiencing a similar issue? Get a personalized answer when you ask a related question.

Have a better answer? Share it in a comment.

Join & Write a Comment

Featured Post

Get expert help—faster!

Need expert help—fast? Use the Help Bell for personalized assistance getting answers to your important questions.

Tackle projects and never again get stuck behind a technical roadblock.
Join Now