Listen and Notify

Hi,

From the documentation I was able to build a trigger firing upon deletion of a record a function that delivers
tablename_operationas a notification one needs to subscribe to. So in terminal I can say LISTEN persons_delete and
instantlywill receive 

    Asynchronous notification "persons_delete" received from server process with PID 54790.

if there was a delete. But what I don't fully understand is how to do this with PQnotifies. Following the docu I get no
notificationseven though I subscribe to them after successfully connecting to the server the same way I do using
terminal.

Googling didn't give me examples I was able to use. Please, can someone help?

Thanks
Alex