Tyrus
Eclipse Tyrus is the open source JSR 356 - Java API for WebSocket
...WebSocket protocol defined by IETF provides bi-directional communication between the server and the remote host. The pros are mainly the ability to communicate both ways, low latency and small communication overhead. Therefore Tyrus and WebSocket in general are suitable for web applications that require sending a huge volume of relatively small messages like online games or market ticker broadcasting.