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9.3

vb.net Async - BeginConnect

Asked by Firmusgrp in Visual Basic Programming, .NET

Tags: vb visual basic async thread

Hello everyone,
This is my first attempt at trying to work with Async thread TCP connection.  I'm trying to change the below code which connects on port 80 (testing TCP communication) to one that uses the Async process.  The idea is so that I can manage the timeout period.  A failure causes the correct (red) icon to show on the form.

Any help migrating to something like the below C code would be greatly apprecaited. 
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**********
My Code
**********
Dim tcpClient As New System.Net.Sockets.TcpClient
        On Error GoTo RedIcon
        tcpClient.Connect("www.yahoo.com", 80)
        Dim networkStream As NetworkStream = tcpClient.GetStream()
        If networkStream.CanWrite And networkStream.CanRead Then
            Dim sendBytes As [Byte]() = Encoding.ASCII.GetBytes("Is anybody listening...")
            networkStream.Write(sendBytes, 0, sendBytes.Length)
            Dim bytes(tcpClient.ReceiveBufferSize) As Byte
            networkStream.Read(bytes, 0, CInt(tcpClient.ReceiveBufferSize))
            Dim returndata As String = Encoding.ASCII.GetString(bytes)
            Me.PictureBox1.Visible = False
            Me.PictureBox2.Visible = True
            tcpClient.Close()
RedIcon:
            Me.PictureBox1.Visible = True
            Me.PictureBox2.Visible = False
            tcpClient.Close()
 
************
Target code sample
*************
 
class TimeOutSocket
{
    private static bool IsConnectionSuccessful = false;
    private static Exception socketexception;
    private static ManualResetEvent TimeoutObject = new ManualResetEvent(false);
 
    public static TcpClient Connect(IPEndPoint remoteEndPoint, int timeoutMSec)
    {
        TimeoutObject.Reset();
        socketexception = null;  
 
        string serverip = Convert.ToString(remoteEndPoint.Address);
        int serverport = remoteEndPoint.Port;           
        TcpClient tcpclient = new TcpClient();
        
        tcpclient.BeginConnect(serverip, serverport, 
			new AsyncCallback(CallBackMethod), tcpclient);
 
        if (TimeoutObject.WaitOne(timeoutMSec, false))
        {
            if (IsConnectionSuccessful)
            {
                return tcpclient;
            }
            else
            {
                throw socketexception;
            }
        }
        else
        {
            tcpclient.Close();
            throw new TimeoutException("TimeOut Exception");
        }
    }
    private static void CallBackMethod(IAsyncResult asyncresult)
    {
        try
        {
            IsConnectionSuccessful = false;
            TcpClient tcpclient = asyncresult.AsyncState as TcpClient;
             
            if (tcpclient.Client != null)
            {
                tcpclient.EndConnect(asyncresult);
                IsConnectionSuccessful = true;
            }
        }
        catch (Exception ex)
        {
            IsConnectionSuccessful = false;
            socketexception = ex;
        }
        finally
        {
            TimeoutObject.Set();
        }
    }
}
[+][-]12/31/08 07:26 PM, ID: 23274054Accepted Solution

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About this solution

Zones: Visual Basic Programming, .NET
Tags: vb visual basic async thread
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Solution Provided By: Arlowin
Participating Experts: 1
Solution Grade: A
 
 
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