There is a nice blog about this. It is unfortunately in German, but the code that is displayed there should still make sense to you.
Source: https://blog.simlau.net/dhl-tracking-api-php.html
Excerpt:
function dhl_tracking($trackingnumber)
{
$data = '<?xml version="1.0" encoding="ISO-8859-1" ?>';
$data .= '<data appname="nol-public" password="anfang" request="get-status-for-public-user" language-code="de">';
$data .= ' <data piece-code="'.$trackingnumber.'"></data>';
$data .= '</data>';
// URL bauen und File hohlen
$xml = simplexml_load_file(sprintf(
'http://nolp.dhl.de/nextt-online-public/direct/nexttjlibpublicservlet?xml=%s', $data
));
// FALSE, wenn Syntax oder HTTP Error
if ($xml === false) return false;
// Wandelt das SimpleXML Objekt in ein Array um
foreach ($xml->data->data->attributes() as $key => $value) {
$return[$key] = (string) $value;
}
return $return;
}
// Aufruf der Funktion
print_r(dhl_tracking($tracking_number));
This function will give back an array that will contain some tracking information:
Array
(
[status] => Die Sendung wurde erfolgreich zugestellt.
[recipient-id-text] => Nachbar
[product-name] => DHL PAKET
[pan-recipient-name] => SIMON LAUGER
)
(In fact, there is WAY more data in there.)
I hope this will help you in some way.