This is a small sample adapted from the xwebSecureClass that shows calling the Authenticate method and getting the soap headers.
NOTE: This code was adapted on the fly and is untested right now, if you find success or bugs please update the code accordingly.
Please note that some client has run into some weird compatibility issue between PHP and .net web serivces regarding how auguments is called on SOAP calls.
<?php
$nfxweb = new SoapClient("https://mynf.mywork.org/xweb/Secure/netFORUMXML.asmx?WSDL",
Array('trace'=>true, //turning on trace=true will let us grab the headers and responses
'exceptions'=>true ));
//these are the params set in the constructor
$authReqParams = Array('userName'=>'bobbojones', 'password' => 'secretsecret');
$responseHeaders = '';
try{
//run the soap call to get it - with the headers.
$response = $nfxweb->__SoapCall("Authenticate", array('parameters'=>$authReqParams), null,null, $responseHeaders);
//Here is the auth token from our response
$authToken = $responseHeaders['AuthorizationToken']->Token;
$xwebNamespace = $response->AuthenticateResult;
} catch(SoapFault $exception) {
throw $exception;
}
//Create the header for our next request.
$authHeaders = new SoapHeader($xwebNamespace, 'AuthorizationToken', Array('Token'=>$authToken), true);
//make our next request, with the new header and capture the token again.
$arguments = Array('szObjectKey'=>"899D54C8-2D34-4E8B-B276-000B80C8958E", 'szObjectName'=>'Individual');
$response = $nfxweb->__soapCall("GetFacadeObject", $arguments, null, $authHeaders, $responseHeaders);
$authToken = $responseHeaders['AuthorizationToken']->Token;
?>