Imports System
Imports System.Net
Imports System.Net.Sockets
Imports System.Text
Imports Microsoft.VisualBasic
 
Public Class frmSynchronousSocketDemo
 
    Dim txtMsg As New TextBox With _
        {.Parent = Me, .Width = 200, .Height = 200, .Multiline = True}
 
    Dim WithEvents btnServer As New Button With _
        {.Parent = Me, .Text = "Start Server", .Top = 210, .Width = 100}
 
    Dim WithEvents btnClient As New Button With _
        {.Parent = Me, .Text = "Send Message", _
         .Top = 210, .Left = 110, .Width = 100}
 
    Dim WithEvents server As SynchronousSocketListenerServer
    Dim client As SynchronousSocketListenerClient
 
    Dim IsServerActive As Boolean
 
    Private Delegate Sub StringDelegate(ByVal str As String)
 
    Dim serverthread As Threading.Thread
    Dim ClientThread as Threading.Thread
 
    Private Sub btnServer_Click(sender As System.Object, _
            e As System.EventArgs) Handles btnServer.Click
 
        If IsServerActive Then
            MsgBox("Der Server ist bereits aktiv") : Exit Sub
        End If
 
        'Server-Instanz starten
        Me.Text = "Gestartet als Server"
        server = New SynchronousSocketListenerServer
        Dim threadstart As New Threading.ThreadStart(AddressOf server.Listen)
        serverthread = New Threading.Thread(threadstart)
        IsServerActive = True
        btnClient.Enabled = False
        serverthread.Start()
    End Sub
 
 
    Private Sub btnClient_Click(sender As System.Object, _
        e As System.EventArgs) Handles btnClient.Click
 
        Me.Text = "Gestartet als Client"
 
        'Text als Nachricht vom Client an den Server senden
        client = New SynchronousSocketListenerClient
        client.TextToSend = txtMsg.Text
        btnServer.Enabled = False
        Dim threadstart As New Threading.ThreadStart(AddressOf client.Send)
        clientthread = New Threading.Thread(threadstart)
        clientthread.Start()
    End Sub
 
 
    Private Sub server_Received(msg As String) Handles server.Received
        'Server hat eine Nachricht empfangen
        Me.Invoke(New StringDelegate(AddressOf ShowMessage), msg)
    End Sub
 
 
    Private Sub ShowMessage(ByVal msg As String)
        txtMsg.Text = "Empfangene Nachricht  " & vbcrlf & _
            Now.ToString & vbCrLf & msg
    End Sub
 
 
    Private Sub frmSynchronousSocketDemo_FormClosing(sender As Object, _
        e As System.Windows.Forms.FormClosingEventArgs) Handles Me.FormClosing
        If IsServerActive Then server.Dispose()
    End Sub
End Class