Visual Basic

<br />
Imports System<br />
Imports System.IO<br />
Imports System.Net<br />
Imports System.Net.Sockets<br />
Imports System.Text<br />
Imports Microsoft.VisualBasic<br />
<br />
<br />
Class MyTcpListener<br />
<br />
    Public Shared Sub Main()<br />
<br />
   Dim server As TcpListener<br />
   server=nothing<br />
        Try<br />
            ' Set the TcpListener on port 13000.<br />
         Dim port As Int32 = 13000<br />
         Dim localAddr As IPAddress = IPAddress.Parse("127.0.0.1")<br />
<br />
         server = New TcpListener(localAddr, port)<br />
         <br />
         ' Start listening for client requests.<br />
         server.Start()<br />
         <br />
         ' Buffer for reading data<br />
            Dim bytes(1024) As Byte<br />
            Dim data As String = Nothing<br />
         <br />
         ' Enter the listening loop.<br />
         While True<br />
            Console.Write("Waiting for a connection... ")<br />
            <br />
            ' Perform a blocking call to accept requests.<br />
            ' You could also user server.AcceptSocket() here.<br />
            Dim client As TcpClient = server.AcceptTcpClient()<br />
            Console.WriteLine("Connected!")<br />
            <br />
            data = Nothing<br />
            <br />
            ' Get a stream object for reading and writing<br />
            Dim stream As NetworkStream = client.GetStream()<br />
            <br />
            Dim i As Int32<br />
            <br />
            ' Loop to receive all the data sent by the client.<br />
            i = stream.Read(bytes, 0, bytes.Length)<br />
            While (i <> 0) <br />
               ' Translate data bytes to a ASCII string.<br />
               data = System.Text.Encoding.ASCII.GetString(bytes, 0, i)<br />
                    Console.WriteLine("Received: {0}", data)<br />
               <br />
               ' Process the data sent by the client.<br />
               data = data.ToUpper()<br />
                    Dim msg As Byte() = System.Text.Encoding.ASCII.GetBytes(data)<br />
               <br />
               ' Send back a response.<br />
               stream.Write(msg, 0, msg.Length)<br />
                    Console.WriteLine("Sent: {0}", data)<br />
              <br />
               i = stream.Read(bytes, 0, bytes.Length)<br />
<br />
            End While<br />
            <br />
            ' Shutdown and end connection<br />
            client.Close()<br />
         End While<br />
      Catch e As SocketException<br />
         Console.WriteLine("SocketException: {0}", e)<br />
      Finally<br />
         server.Stop()<br />
      End Try<br />
      <br />
      Console.WriteLine(ControlChars.Cr + "Hit enter to continue....")<br />
      Console.Read()<br />
   End Sub 'Main<br />
<br />
End Class 'MyTcpListener <br />

<br />
Shared Sub Connect(server As [String], message As [String])<br />
   Try<br />
      ' Create a TcpClient.<br />
      ' Note, for this client to work you need to have a TcpServer <br />
      ' connected to the same address as specified by the server, port<br />
      ' combination.<br />
      Dim port As Int32 = 13000<br />
      Dim client As New TcpClient(server, port)<br />
      <br />
      ' Translate the passed message into ASCII and store it as a Byte array.<br />
      Dim data As [Byte]() = System.Text.Encoding.ASCII.GetBytes(message)<br />
      <br />
      ' Get a client stream for reading and writing.<br />
      '  Stream stream = client.GetStream();<br />
      Dim stream As NetworkStream = client.GetStream()<br />
      <br />
      ' Send the message to the connected TcpServer. <br />
      stream.Write(data, 0, data.Length)<br />
      <br />
      Console.WriteLine("Sent: {0}", message)<br />
      <br />
      ' Receive the TcpServer.response.<br />
      ' Buffer to store the response bytes.<br />
      data = New [Byte](256) {}<br />
      <br />
      ' String to store the response ASCII representation.<br />
      Dim responseData As [String] = [String].Empty<br />
      <br />
      ' Read the first batch of the TcpServer response bytes.<br />
      Dim bytes As Int32 = stream.Read(data, 0, data.Length)<br />
      responseData = System.Text.Encoding.ASCII.GetString(data, 0, bytes)<br />
      Console.WriteLine("Received: {0}", responseData)<br />
      <br />
      ' Close everything.<br />
      stream.Close()<br />
      client.Close()<br />
   Catch e As ArgumentNullException<br />
      Console.WriteLine("ArgumentNullException: {0}", e)<br />
   Catch e As SocketException<br />
      Console.WriteLine("SocketException: {0}", e)<br />
   End Try<br />
   <br />
   Console.WriteLine(ControlChars.Cr + " Press Enter to continue...")<br />
   Console.Read()<br />
End Sub 'Connect<br />