Question about SOAP_WSDL method and the soap message generated

Hello,

I use the SOAP_WSDL method

I have a simple object:

class location
{
var $city;
var $zipCode;
}

I pass this object as a parametter to my webservice:

$wsdl = new SOAP_WSDL('http://xxxxxxxx/service.asmx?wsdl', $proxy);
$Client = $wsdl->getProxy();
$obj = $Client->GetInfo($location);


If for example the variable $zipCode is not initialised, when I call the webservice, the variable is included in the soap message.

is there a way to avoid the empty variables to appear in the soap message?

I know in dotnet there is a way: in that case, I would have created a $zipCodeSpecified variable and when set to false, the $zipCode variable would not have been included in the soap message.

Thank's for your answers,

Yannick