public static void MainSubScription()
        {
            UAEndpointDescriptor endpointDescriptor = "opc.tcp://localhost:4840";
 
            // Instantiate the client object and hook events.
            var client = new EasyUAClient();
 
            client.EventNotification += client_EventNotification;
 
            Console.WriteLine("Subscribing...");
            client.SubscribeEvent(endpointDescriptor, UAObjectIds.Server, 1000);
 
            Console.WriteLine("Processing event notifications for 30 seconds...");
            //System.Threading.Thread.Sleep(30 * 1000);
 
            Console.WriteLine("Unsubscribing...");
            //client.UnsubscribeAllMonitoredItems();
 
            Console.WriteLine("Waiting for 5 seconds...");
            //System.Threading.Thread.Sleep(5 * 1000);
 
            Console.WriteLine("Finished.");
        }
 
        private static void client_EventNotification(object sender, EasyUAEventNotificationEventArgs e)
        {
            // Display the event.
            if (e.EventData is null)
            {
                Console.WriteLine(e.ErrorMessage);
                return;
            }
            Console.WriteLine("All fields:");
            foreach (KeyValuePair<UAAttributeField, ValueResult> pair in e.EventData.FieldResults)
            {
                UAAttributeField attributeField = pair.Key;
                ValueResult valueResult = pair.Value;
                Console.WriteLine("  {0} -> {1}", attributeField, valueResult);
            }
        }