try {
    $client = new SoapClient("http://www.fangbei.org/services/inquiryTracingAndOpcCode?wsdl");
    print_r($client->__getFunctions());
    print_r($client->__getTypes());  
} catch (SOAPFault $e) {
    print $e;
}

Array
(
    [0] => getTracingAndOpcCodeResponse getTracingAndOpcCode(getTracingAndOpcCode $parameters)
)
Array
(
    [0] => struct tracingAndOpcCodeResult {
        string opcCode;
        string tracingNo;
    }
    [1] => struct getTracingAndOpcCode {
        string logisticCode;
    }
    [2] => struct getTracingAndOpcCodeResponse {
        tracingAndOpcCodeResult return;
    }
)

$logisticCode = "3696116566481503";

try {
    $client = new SoapClient('http://www.fangbei.org/services/inquiryTracingAndOpcCode?wsdl');
    $param = array("logisticCode"=>$logisticCode); 
    $result = $client->getTracingAndOpcCode($param);
    var_dump($result);

    if (isset($result->return->opcCode) || !empty($result->return->opcCode)){
        $opcCode = $result->return->opcCode;
        $tracingNo = $result->return->tracingNo;
        var_dump($opcCode);
        var_dump($tracingNo);
    }
    
    $new_logisticCode   = str_pad($logisticCode, 50, "0", STR_PAD_RIGHT);
    $new_opcCode        = str_pad($opcCode, 20, "0", STR_PAD_RIGHT);
    $new_tracingNo      = str_pad($tracingNo, 15, "0", STR_PAD_RIGHT);
    
    
    $data = array(  "trackno"       => $tracingNo,
                    "opccode"       => $opcCode,
                    "logisticscode" => $logisticCode,
                    "secret"       => md5($new_tracingNo.$new_opcCode.$new_logisticCode),
                    );

    $url = "http://wechat.fangbei.org/WeChat/WeChartInterface.ashx";
    $curl = curl_init();
    curl_setopt($curl, CURLOPT_URL, $url);
    curl_setopt($curl, CURLOPT_POST, 1);
    curl_setopt($curl, CURLOPT_POSTFIELDS, $data);
    curl_setopt($curl, CURLOPT_RETURNTRANSFER, 1);
    $output = curl_exec($curl);
    curl_close($curl);
    var_dump($output);
    $response = simplexml_load_string($output, 'SimpleXMLElement', LIBXML_NOCDATA);
    var_dump($response);
    var_dump($response->Response);
    
} catch (SOAPFault $e) {
    print_r('Exception:'.$e);
}