I am using this approach to integrate socket.io with uWebSockets.js. How can I monitor the heartbeat? The header of my connection includes a deviceid, and I want to update the deviceid with a Unix timestamp in Redis every heartbeat. The reason for implementing it this way is to determine whether these devices are currently online or, after killing socket.io, if these machines haven't reconnected, I could deduce they are offline by checking the expiration time along with the Unix timestamp. However, I am not able to catch the heartbeat.