How should I deal with the update function in converting from node to nodelet

[SeokHwanHam]

Hi,
I want to convert a ROS driver in node into nodelet.
For update function which is called every loop such as:

while(ros::OK())
{
update();
ros::spinOnce();
}

How this "update()" call is to be converted in nodelet?

I think createTimer(Duration(0, 0), update) does. But I cannot be assured because I don't exactly know how the ROS Timer works under the hood and I cannot find anything about this by googling.