Salesforce Delegated Authentication PHP Web Service

gistfile1.php

<?php
require_once "nusoap/lib/nusoap.php";

//create the server.
$server = new soap_server;
//set configuration for the web service's WSDL.
$server->configureWSDL('authentication.soap.sforce.com','urn:authentication.soap.sforce.com','',"document");

//register an action called Authenticate.
$server->register(
  'Authenticate',
  array('username'=>'xsd:string','password'=>'xsd:string','sourceIp'=>'xsd:string'),
  array('Authenticated'=>'xsd:boolean')
);

function Authenticate($username, $password, $sourceIp) {
  try{
    $valid = false;
    //Authenticate request here

    return $valid;

  } catch (Exception $e) {
    //write error message a log file $e->getMessage();
    return false;
  }
}

$HTTP_RAW_POST_DATA = isset($HTTP_RAW_POST_DATA) ? $HTTP_RAW_POST_DATA : '';
$server->service($HTTP_RAW_POST_DATA);

?>