<?php    
    $wsdl = 'http://www.webservicex.net/CurrencyConvertor.asmx?WSDL';
    $func = 'ConversionRate';
    $params = array(
        'FromCurrency' => 'USD',
        'ToCurrency' => 'VND',
        );
    
    $client = new SoapClient($wsdl, array('trace' => 1));
    $return = $client->__call($func, array('xxx' => $params));
    
    #var_dump($client->__getLastRequest());
    echo '1USD = ' . number_format($return->ConversionRateResult) . 'VND';