How to use the api to get Custom events provided by the OpenVidu Kurento server

[sravankumar_velanati]

http://builds.openvidu.io/dev/master/latest/kurento-room-docs/websocket_api_room_server.html

In the above link , 17th option says we can use custom events in a room, Can you please explain how to use manage that in server end and how to listen to those custom events in client end.