I have a question regarding a identifying the client by server. When I write a simple helloworld server and client codes all wsdl and other functions are working. But I want to identify the requesting client in server code and respond (To set in return value in hellowold function) that client address back to client. Please help me to solve this.

My nusoap.php in lib folder and all code in 'http://localhost/services/'

Cleint code:
$client = new nusoap_client('http://localhost/services/server.php?wsdl', 'true'); 
echo $result = $client->call('helloworld');

Server code: (server.php)

$server = new soap_server();

array('name' = 'xsd:string'), 
array('return' = 'xsd:string'), 
'Says hello to the caller' 

function helloworld()
return "Hi, ";
// I want to return requester(Client) address (Ip or url) here..................
// Return (This is your address.............)