NuSoap 在函数中使用变量

服务器

$server->wsdl->addComplexType(
    'complexReturn', 'complexType', 'struct', 'all', '',
    array(
    'id' => array('name' => 'id', 'type' => 'xsd:string'),
    'param' => array('name' => 'param', 'type' => 'xsd:string')
    )
);

$server->register('get', array('id' => 'xsd:string', 'param' => 'xsd:string'), //parameters
    array('return' => 'tns:complexReturn'), //output
    'urn:server', //namespace
    'urn:server#getServer', //soapaction
    'rpc', // style
    'encoded', // use
    'description');  //description

function get($id, $param)
{
  return array(
      'id' => $id,
      'param' => $param
  );
}

客户

$client = new SoapClient("http://inner_work/test/nusoap/samples/server.php?wsdl",
      array(
      "trace" => 1,
      "exceptions" => 1,
      "cache_wsdl" => 0,
      "encoding" => "UTF-8",
      'soap_version' => SOAP_1_1,
      'style' => SOAP_DOCUMENT,
      'use' => SOAP_LITERAL,
      ));

  var_dump($client->get(array('id'=>'john', 'param'=>'doe')));

输出对象(stdClass)#2 (2) { ["id"]=> string(5) "Array" ["param"]=> NULL }

如何在 get 函数中使用接收到的变量？