Java test app for Bittrex Websockets using https://github.com/SignalR/java-client

BittrexWebsocket.java

package bittrex;
import java.util.concurrent.ExecutionException;

import microsoft.aspnet.signalr.client.ErrorCallback;
import microsoft.aspnet.signalr.client.LogLevel;
import microsoft.aspnet.signalr.client.Logger;
import microsoft.aspnet.signalr.client.SignalRFuture;
import microsoft.aspnet.signalr.client.hubs.HubConnection;
import microsoft.aspnet.signalr.client.hubs.HubProxy;
import microsoft.aspnet.signalr.client.transport.ServerSentEventsTransport;

public class BittrexWebsocket {
    private static final String DEFAULT_SERVER_URL = "https://www.bittrex.com/signalR/";
    public static void main(String[] args) throws InterruptedException, ExecutionException {
            Logger logger = (message, level) -> {
                if (level == LogLevel.Critical) {
                    System.out.println(level + " " + message);
                }
            };
            HubConnection connection = new HubConnection(DEFAULT_SERVER_URL, null, false, logger);
            
            connection.error(new ErrorCallback() {
                    
                    @Override
                    public void onError(Throwable error) {
                            System.err.println("There was an error communicating with the server.");
                            error.printStackTrace();
                    }
            });
            connection.connected(() -> System.out.println("Connecton started"));
            connection.closed(() -> System.out.println("Connecton closed"));
            
            connection.received(json -> {
                //System.out.println(new Date() + " RECEIVED: " + json);
            });
            
            final HubProxy proxy = connection.createHubProxy("corehub");
            proxy.subscribe(new Object() {
                  @SuppressWarnings("unused")
                  public void updateSummaryState(Object o) {
                          // ignore it for now
                  }
                  @SuppressWarnings("unused")
                  public void updateExchangeState(Object o) {
                      System.out.println("updateExchangeState! " + o.getClass() + ": " + o);
                  }
              });
            
            
            SignalRFuture<Void> start = connection.start(new ServerSentEventsTransport(logger));
            start.get();
            
            SignalRFuture<Void> updates = proxy.invoke("SubscribeToExchangeDeltas", "USDT-BTC");     // -> "updateExchangeState" events
            updates.done(v -> System.out.println("Subscribed for USDT-BTC"));
            updates.onError(err -> {
                System.err.println("Could not subscribe for exchange deltas USDT-BTC");
                err.printStackTrace();
            });
           
            SignalRFuture<Object> state = proxy.invoke(Object.class, "QueryExchangeState", "USDT-BTC");
            state.done(v -> System.out.println("QueryExchangeState for USDT-BTC: " + v));
    }
}