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M2Mqtt in C# is not connected, doesn't give data

I have a project creating a websocket client side (Subscriber) to a MQTT publisher. I am quite new to C# and MQTT protocol. I follow some youtube video to make finish my very first lines connecting to this MQTT publisher to get all the train going in and out Helsinki station.
broker: "rata.digitraffic.fi"
Port: 80
Topic: trains-by-station/HKI (HKI abbr for Helsinki)
I use M2Mqtt library in dotnet to build the subscriber, somehow the client_MqttMsgPublishReceived function is never triggered. the client.IsConnected always returned false value!
You can find info of this mqtt protocol in the url below.
https://www.digitraffic.fi/rautatieliikenne/#websocket-mqtt
It gives me example in JavaScripts and it seems to run fine with the example of each MQTT. But when I tried to do it with my PC, it doesn't give me any thing, but
Hello World!!!
False
and the cmd window on hold.
SOOOO FRUSTRATING right now. it would be much appreciate if anyone can help me out.
BTW, I am using win10, I tried with dotnet 4/5/6 and m2mqtt 4.3.0.
using System.Text;
using uPLibrary.Networking.M2Mqtt;
using uPLibrary.Networking.M2Mqtt.Messages;
using System;
namespace m2qttSubscriber
{
internal class Program
{
static void Main(string[] args)
{
Console.WriteLine("Hello World!!!!");
MqttClient client = new MqttClient("rata.digitraffic.fi",
80,
false,
MqttSslProtocols.None,
null,
null);
client.MqttMsgPublishReceived += client_MqttMsgPublishReceived;
string clientID = "myclientid_" + RandomDigits(4);
client.Connect(clientID);
Console.WriteLine(client.IsConnected);
client.Subscribe(new string[] { "trains-by-station/HKI" },
new byte[] { MqttMsgBase.QOS_LEVEL_AT_MOST_ONCE}) ;
}
static void client_MqttMsgPublishReceived(object sender, MqttMsgPublishEventArgs e)
{
Console.WriteLine("SOme thing is received");
string payload = Encoding.Default.GetString(e.Message);
Console.WriteLine("Recevied {0} from", payload);
}
static public string RandomDigits(int length)
{
var random = new Random();
string s = string.Empty;
for (int i = 0; i < length; i++)
s = String.Concat(s, random.Next(10).ToString());
return s;
}
}
}

As per the comments the library used (uPLibrary.Networking.M2Mqtt) does not support MQTT over Websockets (which is what rata.digitraffic.fi:80 offers).
If you are able to use standard MQTT (over TCP/IP) then rata-mqtt.digitraffic.fi:1883 works (OP succeeded with MqttClient client = new MqttClient("rata-mqtt.digitraffic.fi", 1883, false, MqttSslProtocols.None, null, null);) and this is generally preferable to using WebSockets (there are some situations where you have to use WebSockets; e.g. code running in a browser or to bypass some filters/proxies).
Alternatively there are other libraries that do offer support for MQTT over Websockets.

Connection closes after few seconds when connecting to ActiveMQ set up on AWS

I am connecting to Apache Active MQ which is hosted on AWS to integrate my app to a custom service. I need to keep this running always, not one time like it's right now. The code below works, but only for one message, I need to maintain the connection active all the time listening in order to receive all the messages.
Here is the code.
using Apache.NMS;
using Apache.NMS.Util;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
namespace ApacheMQAsync
{
class Program
{
protected static ITextMessage message = null;
public static void Main(string[] args)
{
Uri connecturi = new Uri("URL:61617");
Console.WriteLine("About to connect to " + connecturi);
// NOTE: ensure the nmsprovider-activemq.config file exists in the executable folder.
IConnectionFactory factory = new Apache.NMS.ActiveMQ.ConnectionFactory(connecturi);
IConnection connection = factory.CreateConnection("username", "password");
ISession session = connection.CreateSession();
IDestination destination = SessionUtil.GetDestination(session, "queue://FOO.BAR");
Console.WriteLine("Using destination: " + destination);
// Create a consumer and producer
IMessageConsumer consumer = session.CreateConsumer(destination);
consumer.Listener += new MessageListener(OnMessage);
connection.Start();
// Wait for the message
if (message == null)
{
Console.WriteLine("No message received!");
}
else
{
Console.WriteLine("Received message with ID: " + message.NMSMessageId);
Console.WriteLine("Received message with text: " + message.Text);
}
}
protected static void OnMessage(IMessage receivedMsg)
{
message = receivedMsg as ITextMessage;
message.Acknowledge();
}
}
}
On the console it displays following
No message received!
and after few seconds the console exist?

There's no real magic there, you need to do something to keep your application running such as pausing on console input or looping on a sleep or other wait type call and then checking something to see if your application should continue. The JMS client isn't guaranteed to keep your application open and running and you should never rely on it to.

Send data from UWP client applications to server crash with error System.Runtime.InteropServices.COMException (0x8007274D)

I want to create a server so that HoloLens, UWP app, could connect to it and send data to it.
So to create the server, I created a Console Application in Visual Studio and followed the example here
And from the client side, UWP application, I created the below class:
using UnityEngine;
#if !UNITY_EDITOR && UNITY_METRO
using System;
using System.Text;
using System.Collections;
using System.Collections.Generic;
using Windows.Networking.Sockets;
using Windows.Storage.Streams;
using Windows.Networking;
using Windows.Foundation;
#endif
public class SendSocketStreamClient {
// The port number for the remote device.
private int port;
private string serverIP;
public SendSocketStreamClient(int portNum, string ip){
port = portNum;
serverIP = ip;
}
#if !UNITY_EDITOR && UNITY_METRO
private StreamSocket networkConnection;
// The response from the remote device.
private static String response = String.Empty;
public void StartClient()
{
// Setup a connection to the server.
HostName networkHost = new HostName(serverIP);
networkConnection = new StreamSocket();
IAsyncAction outstandingAction = networkConnection.ConnectAsync(networkHost, port.ToString());
AsyncActionCompletedHandler aach = new AsyncActionCompletedHandler(NetworkConnectedHandler);
outstandingAction.Completed = aach;
}
public void NetworkConnectedHandler(IAsyncAction asyncInfo, AsyncStatus status)
{
// Status completed is successful.
if (status == AsyncStatus.Completed)
{
DataWriter networkDataWriter;
// Since we are connected, we can send the data we set aside when establishing the connection.
using (networkDataWriter = new DataWriter(networkConnection.OutputStream))
{
networkDataWriter.WriteBytes(Encoding.ASCII.GetBytes("Sending Trial 1"));
// Again, this is an async operation, so we'll set a callback.
DataWriterStoreOperation dswo = networkDataWriter.StoreAsync();
dswo.Completed = new AsyncOperationCompletedHandler<uint>(DataSentHandler);
}
}
else
{
// TODO resend
Debug.Log("Failed to establish connection. Error Code: " + asyncInfo.ErrorCode);
networkConnection.Dispose();
}
}
public void DataSentHandler(IAsyncOperation<uint> operation, AsyncStatus status)
{
if (status == AsyncStatus.Error)
{
// didn't send, so requeue
Debug.Log("Error while sending " + operation.ErrorCode);
}
// Always disconnect here since we will reconnect when sending the next data.
networkConnection.Dispose();
}
#endif
}
I then call this class in a C# script:
#if !UNITY_EDITOR && UNITY_METRO
SendSocketStreamClient newClient = new SendSocketStreamClient(ConnectionPort, ServerIP.Trim());
newClient.StartClient();
#endif
But I always get the error below.
Failed to establish connection. Error Code: System.Runtime.InteropServices.COMException (0x8007274D): No
connection could be made because the target machine actively refused
it.
Any idea what I am doing wrong or how to send data from HoloLens to the server? Is there something wrong with the server?
-----Edit----
Failed to establish connection. Error Code:
System.Runtime.InteropServices.COMException (0x8007274C): A connection
attempt failed because the connected party did not properly respond
after a period of time, or established connection failed because
connected host has failed to respond.
The error changed to the above when I set the serverIP to be the IP address of my machine instead of 127.0.0.1. So I think giving it the right IP address solved this error but now it does not connect to the server.
Does that mean the way I created the server is not right?

As said in the comments above and as here I found that in the server I am using
IPAddress ipAddress = IPAddress.Loopback;
instead of
IPHostEntry ipHostInfo = Dns.Resolve(Dns.GetHostName());
IPAddress ipAddress = ipHostInfo.AddressList[0];
Changing that solved my problem and I was able to connect to the server from HoloLens and receive data.

WPF C# application will freeze my whole computer ever 2-3 times I run it

I put a lot of information in this issue because I have no idea what will be relavent
Issue:
I am having an issue with a program I am working on where when running it, it will freeze my whole computer and return no error (I am completely incapable of doing anything CTRL+ALT+DEL doesn't even work). This program accepts a connection from a android client and atm the android client is not configured correctly so the connection is being rejected.
Question:
How can I stop my program from freezing my entire machine?
Conjecture:
I have a few theories as to what is going on but no idea how to fix them. I have read that this may have something to do with me running a single threaded process inside my async worker but I am not sure that the socket is a single threaded process. Also I am not entirely sure how I am supposed to deal with exceptions in a backgroundworker so I just let it fall back to the RunWorkerCompletedEventArgs then retrieve the error message from there.
What I have tried:
- I tried putting try catches every where then removing try catches nothing seems to be able to capture this error
- I checked my systems event log and nothing is showing up except my restarts after my computer freezes
- I have attempted to isolate the issue but it can literally happen at any point from the program starting till when I attempt to connect
Setup:
I am running the program out of visual studio 2012 professional on a windows 8 pro machine. The computer I am on has a i7-3770K 3.50GHz and 32GB of ram. The application that is attempting to make a connection to mine is a Android application and the credentials are incorrect when it is attempting to connect. Visual Studio is running off my main hard drive and building the project on another drive.
Closing:
With all that said would some one please be willing to help me? If you need any more information I will be happy to provide it, please ask.
Main Method:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;
using System.ComponentModel;
namespace Server
{
/// <summary>
/// Interaction logic for MainWindow.xaml
/// </summary>
public partial class SourceServer : Window
{
private BackgroundWorker worker = new BackgroundWorker();
public SourceServer()
{
InitializeComponent();
StartListeningForConnections();
}
private void StartListeningForConnections()
{
worker.DoWork += new DoWorkEventHandler(worker_DoWork);
worker.RunWorkerCompleted += new RunWorkerCompletedEventHandler(worker_RunWorkerCompleted);
worker.ProgressChanged += new ProgressChangedEventHandler(worker_ProgressChanged);
worker.WorkerReportsProgress = true;
if (worker.IsBusy != true)
{
worker.RunWorkerAsync();
}
}
private void worker_DoWork(object sender, DoWorkEventArgs e)
{
worker.ReportProgress(0, "Source server version 0.0.0.1ib started");
LoginServer oLoginServer = new LoginServer();
oLoginServer.StartListening(worker);
}
private void worker_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
try
{
lvOutput.Items.Add(e.UserState.ToString());
}
catch (Exception exception)
{
lvOutput.Items.Add(exception.StackTrace);
}
}
private void worker_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
if (e.Error != null)
{
System.IO.File.WriteAllText(Environment.CurrentDirectory + #"\log.txt", e.Error.StackTrace + " /n " + e.Error.Message);
}
else
{
MessageBox.Show("Error was null");
}
worker.Dispose();
}
}
}
SSL Socket Connection:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Threading;
using System.Net;
using System.Net.Sockets;
using System.Windows;
using System.Windows.Controls;
using System.ComponentModel;
using System.Net.Security;
using System.Security.Cryptography.X509Certificates;
using MySql.Data.MySqlClient;
using System.IO;
namespace Server
{
public class LoginServer
{
// Incoming data from the client.
public static string data = null;
public static X509Certificate serverCertificate = null;
public delegate void UpdateListView(ListView oOutput);
public void StartListening(BackgroundWorker worker)
{
// Data buffer for incoming data.
byte[] bytes = new Byte[1024];
// Establish the local endpoint for the socket.
IPHostEntry ipHostInfo = Dns.GetHostEntry(Dns.GetHostName());
IPAddress ipAddress = ipHostInfo.AddressList[1];
serverCertificate = X509Certificate.CreateFromCertFile(#"server.crt");
TcpListener oServer = new TcpListener(ipAddress, 12345);
// Bind the socket to the local endpoint and
// listen for incoming connections.
// Start listening for connections.
while (true)
{
Thread.Sleep(100);
worker.ReportProgress(0, "Waiting for connection....");
// Program is suspended while waiting for an incoming connection.
//Socket handler = listener.Accept();
oServer.Start();
TcpClient oClient = oServer.AcceptTcpClient();
Stream oStream = oClient.GetStream();
SslStream oSSLStream = new SslStream(oStream);
data = null;
// An incoming connection needs to be processed.
string sUsername = "place holder";
string sPassword = "place holder";
while (true)
{
bytes = new byte[1024];
int bytesRec = oSSLStream.Read(bytes, 0, bytes.Length);
data += Encoding.ASCII.GetString(bytes, 0, bytesRec);
string[] sCredentials = data.Split("|".ToCharArray()[0]);
sUsername = sCredentials[0];
sPassword = sCredentials[1];
if (data.IndexOf("<EOF>") > -1)
{
break;
}
}
// Show the data on the console.
worker.ReportProgress(0, "Connection Recieved : ");
worker.ReportProgress(0, "Username: " + sUsername);
worker.ReportProgress(0, "Password: " + sPassword);
worker.ReportProgress(0, "");
// Echo the data back to the client.
byte[] msg;
if (sUsername.Equals("test") && sPassword.Equals("test"))
{
msg = Encoding.ASCII.GetBytes("approved<EOF>\n");
worker.ReportProgress(0, "approved");
oSSLStream.Write(msg, 0, msg.Length);
}
else
{
msg = Encoding.ASCII.GetBytes("rejected<EOF>\n");
worker.ReportProgress(0, "rejected");
oSSLStream.Write(msg, 0, msg.Length);
}
}
}
public void VerifyUser()
{
}
}
}

While I don't see any reason for this to lock up your entire computer, I do see a couple of reasons for the application to potentially hang...
Your while loop inside of your SSL server will never break unless your client writes '<EOF>' to the stream; which you would have to force it to do. I would likely do something similar to this:
while(( bytesRec = oSSLStream.Read(bytes,0,bytes.Length)) > 0 )
{
// Compare input & break
}
-- The while loop you have now ( without a thread sleep ) will consume all of your systems resources waiting for ... something that may never occur.
In a related issue - I note that your 'DoWork' method launches the listener - but does not start a new thread for this listener. This means that the listener is running inside of your interface thread - which will cause the interface ( and potentially more... ) to hang until the process is completed - which as stated, may never happen.
... Ahem... This last paragraph may be incorrect - you are running an async worker, so I may be incorrect in my second assessment.
Cheers, hope this is helpful.

I've had some hanging problems on Windows 8 that I never saw on Windows 7 (with VS2012). As you experienced it worked fine the first time but only locked up Visual Studio (and not my whole machine) and I had to force quit.
The Visual Studio 2012 Update 4 (which focuses on bug fixes and compatibility) seemed to fix it, although I didn't scientifically test this.
Note: As of 9/1/13 this is only the RC2 version so please check for newer versions, and edit this answer when RTM happens.

Testing of socket communication program

Am starting with socket programming with a simple UDPClient program to send some data. The large code snippet is below:
using System;
using System.Text;
using System.Net;
using System.Net.Sockets;
using System.Threading;
class ShowIP
{
public static void Main(string[] args)
{
string name = Dns.GetHostName();
//name = "GSL1460";
name = "GSL1296";
try
{
IPAddress[] addrs = Dns.GetHostEntry(name).AddressList;
foreach (IPAddress addr in addrs)
Console.WriteLine("{0}/{1}", name, addr);
Console.WriteLine("Started listening");
Thread listenerThread = new Thread(new ThreadStart(StartListeningUDP));
listenerThread.Start();
Console.WriteLine("Started sending");
for (int counter = 0; counter <= 3; counter++)
{
Thread.Sleep(1000);
Console.WriteLine("Sending {0} time", counter.ToString());
StartSendingUDP(addrs[0]);
}
Console.ReadLine();
}
catch (Exception e)
{
Console.WriteLine(e.Message);
}
}
private static void StartListeningUDP()
{
UdpClient udpListener = null;
IPEndPoint nwPoint = new IPEndPoint(IPAddress.Any, 12345);
while (true)
{
try
{
udpListener = new UdpClient(12345);
Console.WriteLine("Waiting to receive");
Byte[] receivedBytes = udpListener.Receive(ref nwPoint);
string receivedData = Encoding.ASCII.GetString(receivedBytes);
Console.WriteLine("Data received : " + receivedData);
}
catch (Exception e)
{
Console.WriteLine(e.Message);
}
finally
{
udpListener.Close();
}
}
}
private static void StartSendingUDP(IPAddress clientAddress)
{
UdpClient udpSender = new UdpClient();
try
{
Byte[] sendBytes = Encoding.ASCII.GetBytes("Say HI to Papa...");
Console.WriteLine("Data Sent : Say HI to Papa...");
udpSender.Send(sendBytes, sendBytes.Length, new IPEndPoint(clientAddress, 12345));
}
finally
{
udpSender.Close();
}
}
}
The sample works fine on local machine, but am not able to send data to another machine on the intranet.
During testing
Am uncommenting the appropriate code to send data to his machine
Am running the Receiver bit on his machine
Have checked that the required port is open on his machine
Am I missing something? Please suggest.

udpSender.Flush?

I'm not a C# person, so I can't comment too much on your code, but it looks basically okay. Make sure that the IP address you're sending to is being resolved correctly to your receiving machine.
Also, see if Windows has firewalled your internet connection, and try disabling the firewall if so. And, I know that Microsoft has some ideas about "safe" code that have caused us some problems in the past. I don't have any specifics, but there might be settings in the project that keep it from being able to access the network.

The UDP-Listener might be listening on localhost only. You could try to replace
udpListener = new UdpClient(12345)
in StartListeningUDP() with
udpListener = new UdpClient(new IPEndPoint(IPAddress.Any,12345))

you can't really send UDP over the internet without doing few things before.
you will get too many udp filters on the way.
even if you will disable your firewall, your router/provider modem can be set to block it.
else - your provider servers will block it.
so in fact you will have to make sure that this port is open for UDP, just as on your localhost it won't work unless you will open this port in the firewall and/or install the loopback adapter