Question

My code:

<? 
    $url = 'http://w1.weather.gov/xml/current_obs/KGJT.xml'; 
    $xml = simplexml_load_file($url); 
?>

<? 
    echo $xml->weather, " ";
    echo $xml->temperature_string;
?>

This works great, but I read that caching external data is a must for page speed. How can I cache this for lets say 5 hours?

I looked into ob_start(), is this what I should use?

Answer 1

The ob system is for in-script cacheing. It’s not useful for persistent multi invocation caching.

To do this properly, you’d write the resulting xml out of a file. Every time the script runs, you’d check the last updated time on that file. if it’s > 5 hours, you fetch/save a fresh copy.

e.g.

$file = 'weather.xml';
if (filemtime($file) < (time() - 5*60*60)) {
    $xml = file_get_contents('http://w1.weather.gov/xml/current_obs/KGJT.xml');
    file_put_contents($file, $xml);
}
$xml = simplexml_load_file($file); 

echo $xml->weather, " ";
echo $xml->temperature_string;