terminate()

This method is how the node tells us we're about to get shut down. In this example we don't need to tidy anything up so we ignore the call.

But in general we can take whatever action is required. We get to know when we're due to terminate as a date. And we also get a callback interface so we can inform the node of our progress as we tidy up. The node's administrator might look at this and give us a bit more time if it looks like we're doing well but need a bit more leeway. Or they might notice we're stuck and shut us off straight away.