I created a websocket (with perl Net::WebSocket::Server but I think it does not matter). My question is that when I close the website tab(not necessarily the whole browser) the server will disconnect the specific socket (my disconnect event is called). How the server manage to know that? I can not find a straight detailed description.
Each side terminates its end of the connection by sending a special message with the FIN (finish) bit set. This message, sometimes called a FIN, serves as a connection termination request to the other device, while also possibly carrying data like a regular segment. The device receiving the FIN responds with an acknowledgment to the FIN to indicate that it was received. The connection as a whole is not considered terminated until both sides have finished the shut down procedure by sending a FIN and receiving an ACK.