ClientWebSocketEndpoint.java

package org.vivek.j2ee.websockets.client;
import javax.websocket.*;
import java.io.IOException;
import java.nio.ByteBuffer;
public class ClientWebSocketEndpoint extends Endpoint {
 @Override public void onOpen(final Session session, EndpointConfig config) {
  try {
   session.getBasicRemote().sendText("Joining");
  } catch (IOException e) {
   e.printStackTrace();
  }
  session.addMessageHandler(new MessageHandler.Whole < String > () {
   @Override public void onMessage(String message) {
    System.out.println(message);
   }
   public void onMessage(PongMessage pongMessage) {
    System.out.println(pongMessage);
   }
  });
  new Thread(new Runnable() {
   @Override public void run() {
    ByteBuffer buffer = ByteBuffer.allocate(1);
    buffer.put((byte) 0xFF);
    try {
     session.getBasicRemote().sendPing(buffer);
     Thread.sleep(2000);
    } catch (IOException | InterruptedException e) {
     e.printStackTrace();
    }
   }
  }).start();
 }
}