How To: create a cluster of netty socketio servers for high availabiliy (i.e. failover) purposes

In order to provide high availability for your solution based on netty-socketio server, the suggestion is to use several netty-socketio instances and any load-balancing proxy (i.e. NGINX with iphash, HAProxy) on top of your netty-socketio cluster.

This way, as soon as one server goes down, the client will try to reconnect and the load-balancer will redirect it to the other running server. From client point of view, there won't be much delay in that redirection/new connection. A good description of use case scenario and solution is provided here.

Take into account that once you have the cluster of netty-socketio servers setup for high availability, just by adding a Redisson or Hazelcast server, you can easily get the capability of broadcasting messages across multiple servers as described here