PHP : soapCall with complex arguments - php

Question

I'm trying to set up a SOAP connexion between a supplier and I in order to synchronize data between our databases.
I've managed to connect him with a simple soapCall threw that php lines ($service is the name of the Soap function I'm reaching, and $data is an associative array that contains my variables) :
$request = new SoapClient($client, array('soap_version' => SOAP_1_1));
$response = $request->$service($data);
That lines work if my XML scheme of variables has no collections like in this example :
<?xml version="1.0" encoding="utf-8"?>
<soap:Envelope xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/">
<soap:Body>
<ServiceITryToReach xmlns="https://mysuplier:65100/">
<Login>login</Login>
<Password>pass</Password>
<Variables>
<Variable1>data</Variable1>
<Variable2>data</Variable2>
</Variables>
</ServiceITryToReach>
</soap:Body>
</soap:Envelope>
In the example above, my associative array that contains my variables will be :
array('Login'=>'login','Password'=>'pass','Variables'=>array('Variable1'=>'data','Variable2'=>'data'));
But, if my XML scheme contains collections of variables of same type, how can I represent it with an associative array in PHP ?
<?xml version="1.0" encoding="utf-8"?>
<soap:Envelope xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/">
<soap:Body>
<ServiceITryToReach xmlns="https://mysuplier:65100/">
<Login>login</Login>
<Password>pass</Password>
<Variables>
<Variable>
<data>data</data>
</Variable>
<Variable>
<data>data</data>
</Variable>
<Variable>
<data>data</data>
</Variable>
</Variables>
</ServiceITryToReach>
</soap:Body>
</soap:Envelope>
In conclusion, I'm looking for another simple way to request my supplier with multiple variables. The best would be to have a direct XML input in my soapCall method instead of an associative array.
An idea ?
Thanks,
Nico