Imports System
Imports System.Windows.Forms
Imports System.Drawing
Imports System.Net.Sockets
Imports System.Threading
Imports System.IO
Imports System.ComponentModel
Namespace MyNamespace
    Public Class Chat
        Inherits Form
        Public Delegate Sub Invoker(ByVal t As String)
        Private thdListener As Thread
        Private objListener As TcpListener
        Private objClient As TcpClient
 
        Private btSend As New Button()
        Private rtbMessage As New RichTextBox()
        Private rtbType As New RichTextBox()
        Private strFriend As String
        Private strMe As String
        Public Sub New()
            strFriend = "127.0.0.1"
            strMe = "Chris"
            thdListener = New Thread(New ThreadStart(Me.Listen))
            thdListener.Start()
            rtbMessage.Dock = DockStyle.Top
            rtbMessage.Size = New Size(300, 200)
            rtbType.Location = New Point(0, 205)
            rtbType.Size = New Size(240, 65)
            btSend.Text = "Send"
            AddHandler btSend.Click, AddressOf SendText
            btSend.Size = New Size(50, 50)
            btSend.Location = New Point(240, 205)
            Me.Text = ".NET IM"
            Me.Size = New Size(300, 300)
            AddHandler Me.Closing, AddressOf CloseMe
            Me.Controls.Add(btSend)
            Me.Controls.Add(rtbMessage)
            Me.Controls.Add(rtbType)
        End Sub
        Private Sub SendText(ByVal Sender As Object, ByVal e As EventArgs)
            rtbMessage.Text += strMe + ": " + rtbType.Text + "" & Chr(10) & ""
            objClient = New TcpClient(strFriend, 1000)
            Dim w As New StreamWriter(objClient.GetStream())
            w.Write(rtbType.Text + "" & Chr(10) & "")
            w.Flush()
            objClient.Close()
            rtbType.Text = ""
        End Sub
        Private Sub Listen()
            Dim strTemp As String = ""
            objListener = New TcpListener(1000)
            objListener.Start()
            Do
                Dim objClient As TcpClient = objListener.AcceptTcpClient()
                Dim objReader As New StreamReader(objClient.GetStream())
                While objReader.Peek() <> -1
                    strTemp += Convert.ToChar(objReader.Read()).ToString()
                End While
                Dim objParams As Object() = New Object() {strTemp}
                strTemp = ""
                Me.Invoke(New Invoker(Me.ShowMessage), objParams)
            Loop While True <> False
        End Sub
        Private Sub ShowMessage(ByVal t As String)
            rtbMessage.Text += strFriend + ": " + t + "" & Chr(10) & ""
        End Sub
        Private Sub CloseMe(ByVal Sender As Object, ByVal e As CancelEventArgs)
            objListener.[Stop]()
        End Sub
        Public Shared Sub Main()
            Application.Run(New Chat())
        End Sub
    End Class
End Namespace