PHP controls the Web page Expiration Time program

Sometimes we need to control the expiration time of pages such as the home page. But we use the ChinaCache CDN For example, so how to design to let him cache my content.

Sometimes we need to control the expiration time of pages such as the home page. But we use the ChinaCache CDN For example, so how to design to let him cache my content.

Of course, the prerequisite is to open a CDN in a function reload_into_ims on. So the user sent over the No-cache is not afraid. Because it will give No-cache to If-modified-since. So we write the program is mainly to if-modified-since control just fine. Remember, the caching system architecture is best controlled by the backend, so the best approach is to manage the expiration of the program. Oh, I only can php, just write one in PHP, the other program is the same.

See my following procedure, hehe, 5 minutes overdue.

<?php
$headers = Apache_request_headers ();
$client _time = (isset ($headers [' if-modified-since '])? Strtotime ($headers [' if-modified-since ']): 0);
$now =gmmktime ();
$now _list=gmmktime () -60*5;
if ($client _time< $now and $client _time > $now _list) {
Header (' last-modified: ' Gmdate (' d, D M Y h:i:s ', $client _time). ' GMT ', true, 304);
Exit (0);
}else{
Header (' last-modified: ' Gmdate (' d, D M Y h:i:s ', $now). ' GMT ', true, 200);
}
?>