Permitting local runs only. Source code:

<?php 
if (isset($_SERVER['REMOTE_ADDR'])) {
    echo "Permitting local runs only. Source code:\n";
    highlight_file(__FILE__);
    exit;
}

if (!file_exists("data.serialized")) {
    echo "Missing data.serialized, trying to parse from data.xml... ";

    if (!file_exists('data.xml')) {
        die("Missing data.xml.\n");
    }

    require('xml2arrayparser.php');
    $dom = new xmlToArrayParser(file_get_contents('data.xml'));
    $data = $dom->array; 

    if ($dom->parse_error) {
        die('Error: ' . $dom->get_xml_error()); 
    }

    $fid = fopen('data.serialized', 'w');
    fwrite($fid, gzcompress(serialize($data)));
    fclose($fid);

    unset($dom);

    echo "Done!\n";
}

if (!file_exists('events.serialized')) {
    echo "Missing events.serialized, trying to parse from data.serialized... ";

    $data = unserialize(gzuncompress(file_get_contents('data.serialized')));

    $scheduleversion = $data['schedule']['version'];

    foreach ($data['schedule']['day'] as $day=>$daydata) {
        //echo "Day $day:\n";
        foreach ($daydata['room'] as $room) {
            //echo "  " . $room['attrib']['name'] . ":\n";
            foreach ($room['event'] as $event) {
                $ev = [];
                $ev['room'] = $room['attrib']['name'];
                $ev['day'] = $day;
                foreach ($event as $key=>$val) {
                    if ($key == 'persons' && isset($val['person'])) {
                        $ev['speakers'] = [];
                        foreach ($val['person'] as $person) {
                            if (is_numeric($person)) {
                                $ev['speakers'][$person] = true;
                            }
                            else if (is_string($person)) {
                                $ev['speakers'][$person] = $person;
                            }
                            else if (isset($person['id'])) {
                                $ev['speakers'][$person['id']] = true;
                            }
                            else {
                                if (!isset($person['attrib'])) { print_r($person); exit; }
                                $ev['speakers'][$person['attrib']['id']] = $person['cdata'];
                            }
                        }
                    }
                    else {
                        $ev[$key] = $val;
                    }
                }
                $events[] = $ev;
            }
        }
    }

    $events['schedule-version'] = $scheduleversion;

    $fid = fopen('events.serialized', 'w');
    fwrite($fid, gzcompress(serialize($events)));
    fclose($fid);

    echo "Done!\n";
}

$events = unserialize(gzuncompress(file_get_contents('events.serialized')));

if (!$events) {
    echo "Error decoding events.\n";
}

foreach ($events as $event) {
    if ($event['language'] != 'de' && $event['language'] != 'en') {
        print_r($event);
    }
}