Caching example using APC cache. Requires installation of the APC extension.

<?php

// Caching using APC cache. PHP4/PHP5
// Caching code by Rasmus Lerdorf
// February 1, 2006
// Requires installation of the APC extension

error_reporting(E_ALL);

$request = 'http://search.yahooapis.com/ImageSearchService/V1/imageSearch?appid=YahooDemo&query=Madonna&results=1';

// Number of seconds until the cache gets stale
$cache_timeout = 7200;

// Check the cache
$response = request_cache($request, $cache_timeout);

if ($response === false) {
  die('Request failed');
}

// Output the XML
echo htmlspecialchars($response, ENT_QUOTES);

// This is the main caching routine. More robust error checking should
// be implemented.

function request_cache($url, $ttl) {

  if (!$xml = apc_fetch($url)) {
    $xml = file_get_contents($url);
    if ($xml === false)
      return false;
    apc_store($url, $xml, $ttl);
  }
  return $xml;
}

?>