Adding timer to a running WampServer

[Alexandros G.]

I am setting up a WampServer with Ratchet. Is it possible to add to the loop a timer that calls a WampServer's method every 30 second?

I have tried the following code:

public function addMonitoringTimer(){

    $this->loop->addPeriodicTimer(30, function() {
        ...
        $this->wampServer->methodName();
        ...
    });

} 

but no timers seems to work.

Note: As this code is a class method, $this is a reference to the class object that has references to the WampServer ($this->wampserver) and the loop used by the WampServer ($this->loop). The method I am calling is not part of the WampServerInterface.