How will I constantly listen to the port using the graphical interface?

Question

Hi guys, I'm trying to learn the TCP / TCP client interaction. I want to know how I listen to the port all the time using the graphical interface. I am currently using this code:

private void Form1_Load(object sender, EventArgs e) { CreateServer(); } void CreateServer() { TcpListener tcp = new TcpListener(25565); tcp.Start(); Thread t = new Thread(() => { while (true) { var tcpClient = tcp.AcceptTcpClient(); ThreadPool.QueueUserWorkItem((_) => { Socket s = tcp.AcceptSocket(); console.Invoke((MethodInvoker)delegate { console.Text += "Connection esatblished: " + s.RemoteEndPoint + Environment.NewLine; }); byte[] b = new byte[100]; int k = s.Receive(b); for (int i = 0; i < k; i++) { console.Text += Convert.ToChar(b[i]); incoming += Convert.ToChar(b[i]); } MessageBox.Show(incoming); console.Invoke((MethodInvoker)delegate { console.Text += incoming + Environment.NewLine; }); list.Invoke((MethodInvoker)delegate { list.Items.Add(incoming); }); ASCIIEncoding asen = new ASCIIEncoding(); s.Send(asen.GetBytes("\n")); tcpClient.Close(); }, null); } }); t.IsBackground = true; t.Start(); } 

Any help would be greatly appreciated.

Answer 1

Short answer - run the TCP listener in a separate thread / task (TPL). For a complete working solution, you also need to implement sending any changes to a separate user interface, using a separate thread in the main thread, using a special technique that depends on the Framework you use. I mean WPF / WinForms / whatever.

The code below works fine for me. Read the TODO section before.

TODO:

• Add to the form Textbox, ListBox, Button, make public:

   public System.Windows.Forms.TextBox console; public System.Windows.Forms.ListBox incommingMessages; private System.Windows.Forms.Button sendSampleDataButton; 

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Point of entry:

 private static Form1 form; [STAThread] static void Main() { Application.EnableVisualStyles(); Application.SetCompatibleTextRenderingDefault(false); form = new Form1(); form.Load += OnFormLoad; Application.Run(form); } private static void OnFormLoad(object sender, EventArgs e) { CreateServer(); } 

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Server:

 private static void CreateServer() { var tcp = new TcpListener(IPAddress.Any, 25565); tcp.Start(); var listeningThread = new Thread(() => { while (true) { var tcpClient = tcp.AcceptTcpClient(); ThreadPool.QueueUserWorkItem(param => { NetworkStream stream = tcpClient.GetStream(); string incomming; byte[] bytes = new byte[1024]; int i = stream.Read(bytes, 0, bytes.Length); incomming = System.Text.Encoding.ASCII.GetString(bytes, 0, i); form.console.Invoke( (MethodInvoker)delegate { form.console.Text += String.Format( "{0} Connection esatblished: {1}{2}", DateTime.Now, tcpClient.Client.RemoteEndPoint, Environment.NewLine); }); MessageBox.Show(String.Format("Received: {0}", incomming)); form.incommingMessages.Invoke((MethodInvoker)(() => form.incommingMessages.Items.Add(incomming))); tcpClient.Close(); }, null); } }); listeningThread.IsBackground = true; listeningThread.Start(); } 

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Client

 private void button1_Click(object sender, EventArgs e) { Connect("localhost", "hello localhost " + Guid.NewGuid()); } static void Connect(String server, String message) { try { Int32 port = 25565; TcpClient client = new TcpClient(server, port); Byte[] data = System.Text.Encoding.ASCII.GetBytes(message); NetworkStream stream = client.GetStream(); // Send the message to the connected TcpServer. stream.Write(data, 0, data.Length); stream.Close(); client.Close(); } catch (ArgumentNullException e) { Debug.WriteLine("ArgumentNullException: {0}", e); } catch (SocketException e) { Debug.WriteLine("SocketException: {0}", e); } } 

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Screenshot:

Answer 2

Create a stream, start listening to it and don’t stop the server

 void CreateServer() { TcpListener tcp = new TcpListener(25565); tcp.Start(); Thread t = new Thread(()=> { while (true) { var tcpClient = tcp.AcceptTcpClient(); ThreadPool.QueueUserWorkItem((_) => { //Your server codes handling client request. //Don't access UI control directly here //Use "Invoke" instead. tcpClient.Close(); },null); } }); t.IsBackground = true; t.Start(); } 

Answer 3

You can use the threading approach (as mentioned in other answers) or use asynchronous sockets , which are better in my version. And even better, you can use the asynchronous model proposed by SocketAsyncEventArgs . Asynchronous sockets will benefit from the use of completion ports .

Answer 4

here is a good example on mdsn: Asynchronous server socket example