callback = function (packet, index, total) {
	    // if its the first message we consider the transport open
	    if ('opening' === self.readyState) {
	      self.onOpen();
	    }
	
	    // if its a close packet, we close the ongoing requests
	    if ('close' === packet.type) {
	      self.onClose();
	      return false;
	    }
	
	    // otherwise bypass onData and handle the message
	    self.onPacket(packet);
	  }
Overloads onData to detect payloads.

@api private