Main.java

package modern.challenge;

import java.net.URI;
import java.net.http.HttpClient;
import java.net.http.WebSocket;
import java.net.http.WebSocket.Listener;
import java.util.concurrent.CompletionStage;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;

public class Main {

    public static void main(String[] args) 
            throws InterruptedException, ExecutionException, TimeoutException {

        Listener wsListener = new Listener() {
            @Override
            public CompletionStage<?> onText(WebSocket webSocket,
                    CharSequence data, boolean last) {

                System.out.println("Received data: " + data);

                return Listener.super.onText(webSocket, data, last);
            }

            @Override
            public void onOpen(WebSocket webSocket) {
                System.out.println("Connection is open ...");
                Listener.super.onOpen(webSocket);
            }

            @Override
            public CompletionStage<?> onClose(WebSocket webSocket, int statusCode,
                    String reason) {
                System.out.println("Closing connection: " + statusCode + " " + reason);
                return Listener.super.onClose(webSocket, statusCode, reason);
            }
        };

        HttpClient client = HttpClient.newHttpClient();

        WebSocket webSocket = client.newWebSocketBuilder()
                .buildAsync(URI.create("ws://stream.meetup.com/2/rsvps"), wsListener)
                .get(10, TimeUnit.SECONDS);
        
        // webSocket.sendText("I am an Meetup RSVP fan", true);

        TimeUnit.SECONDS.sleep(10);
        webSocket.sendClose(WebSocket.NORMAL_CLOSURE, "ok");
    }
}