[zeromq-dev] Use zmq_socket_monitor for heartbeating

[Felipe Farinon]

I am thinking of using zmq_socket_monitor for creating a heartbeat strategy.

But I would like to know when it notifies that a disconnection occured? 
Is it when I try to send some data in the socket and the OS tells that 
the socket that it has been disconnected? Or is it when the endpoint 
closes the connection even if it's not closed graciously?