cakephp webservice

I have problem in creating web-service using cakephp .
this what i do to create this web-service .
I use NuSOAP - Web Services Toolkit for PHP for this.
I create a controller called WsController and import the library on it.

class WsController extends AppController{

var $uses = array();

function info()  {
    $this->layout= null;
    $ns="http://www.techvoicellc.com/Tutorials//"; 
	$server = new soap_server(); 


	$server->configureWSDL('mostafa',$ns); 
	$server->wsdl->schemaTargetNamespace=$ns; 
	$server->wsdl->addComplexType('ArrayOfstring','complexType', 
    'array','','SOAP-ENC:Array',array()
    ,array(array('ref'=>'SOAP-ENC:arrayType','wsdl:arrayType'=>'string[]')), 
    'xsd:string'); 


 	$server->register('sum', 
    array('x' => 'xsd:integer','y' => 'xsd:integer'),        
    array('z' => 'xsd:integer'),   
    $ns,                                           
    "$ns#sum",                               
    'rpc',                                        
    'encoded',                                    
    'documentation'     // documentation 
    );  

    $server->service($HTTP_RAW_POST_DATA); 
}

 function sum($x,$y){ 
	$z=$x+$y;
	return new soapval('return','xsd:integer',$z);
 } 

}

and i create the clint in controller action like this

function index() {
   $wsdl = 'http://localhost/asd/ws/info?wsdl';
   $client = new nusoap_client ( $wsdl, true );

   $this->client = new nusoap_client($wsdl, true);
   $param1 = array ('x' => 2, 'y' => 1 );
   $a = $client->call ( 'sum', $param1 );
    echo $a;
 }

it don't do any thins although that i create this in non cake project and its work very well

hope some one tell me what is the best practise to create web-service in cake php