<?php
var $path = './tmp/';
var $fileName = 'feed_me_raw';
var $pathFileName = $path.$fileName;
var $raw_feed_data = '';

// check to see if raw feed is cached.
// if it is, load it, if not, create it.

if(file_exists($pathFileName))
{
    $raw_feed_data = file_get_contents($pathFileName);
}
else
{
    //
    // put code to create $raw_feed_data here ...
    //
    $fp = fopen($pathFileName, 'w');
    if ($fp)
    {
        fwrite($fp, $raw_feed_data);
        fclose($fp);
    }
}
$feed = new SimplePie();
$feed->set_raw_data($raw_feed_data);
$feed->init();
?>

// http://simplepie.org/wiki/reference/simplepie/set_raw_data