Abdul Basit Abdul Basit - 2 months ago 8
C# Question

Asynchronous Socket C# Sending Data but not Recieving

Here is my code . I am successfully sending data but not receiving any data . here is my code below . I am actually sending 23 bytes over the socket and its executing the event but its not receiving the data server is sending back . I want to have persistent bi directional connection to send and receive data

using System;
using System.Net;
using System.Net.Sockets;
using System.Threading;
using System.Text;
using System.Collections.Generic;

// State object for receiving data from remote device.
public class StateObject
{
// Client socket.
public Socket workSocket = null;
// Size of receive buffer.
public const int BufferSize = 256;
// Receive buffer.
public byte[] buffer = new byte[BufferSize];
// Received data string.
public StringBuilder sb = new StringBuilder();
}

public class AsynchronousClient
{
// The port number for the remote device.
private const int port = 18001;

// ManualResetEvent instances signal completion.
private static ManualResetEvent connectDone =
new ManualResetEvent(false);
private static ManualResetEvent sendDone =
new ManualResetEvent(false);
private static ManualResetEvent receiveDone =
new ManualResetEvent(false);

// The response from the remote device.
private static String response = String.Empty;

private static void StartClient()
{
// Connect to a remote device.
try
{


IPEndPoint remoteEP = new IPEndPoint(IPAddress.Parse("192.168.1.140"), port);

// Create a TCP/IP socket.
Socket client = new Socket(AddressFamily.InterNetwork,SocketType.Stream, ProtocolType.Tcp);
// Connect to the remote endpoint.
client.BeginConnect(remoteEP, new AsyncCallback(ConnectCallback), client);
connectDone.WaitOne();

// Send test data to the remote device.
Send(client, "This is a test<EOF>");
sendDone.WaitOne();

// Receive the response from the remote device.
Receive(client);
receiveDone.WaitOne();

// Write the response to the console.
Console.WriteLine("Response received : {0}", response);

// Release the socket.
client.Shutdown(SocketShutdown.Both);
client.Close();

}
catch (Exception e)
{
Console.WriteLine(e.ToString());
}
}

private static void ConnectCallback(IAsyncResult ar)
{
try
{
// Retrieve the socket from the state object.
Socket client = (Socket)ar.AsyncState;

// Complete the connection.
client.EndConnect(ar);

Console.WriteLine("Socket connected to {0}",
client.RemoteEndPoint.ToString());

// Signal that the connection has been made.
connectDone.Set();
}
catch (Exception e)
{
Console.WriteLine(e.ToString());
}
}

private static void Receive(Socket client)
{
try
{
// Create the state object.
StateObject state = new StateObject();
state.workSocket = client;

// Begin receiving the data from the remote device.
client.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0,
new AsyncCallback(ReceiveCallback), state);
}
catch (Exception e)
{
Console.WriteLine(e.ToString());
}
}

private static void ReceiveCallback(IAsyncResult ar)
{
try
{

StateObject state = (StateObject)ar.AsyncState;
Socket client = state.workSocket;

// Read data from the remote device.
int bytesRead = client.EndReceive(ar);

if (bytesRead > 0)
{
// There might be more data, so store the data received so far.
state.sb.Append(Encoding.ASCII.GetString(state.buffer, 0, bytesRead));

// Get the rest of the data.
client.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0,
new AsyncCallback(ReceiveCallback), state);
}
else
{
// All the data has arrived; put it in response.
if (state.sb.Length > 1)
{
response = state.sb.ToString();
}
// Signal that all bytes have been received.
receiveDone.Set();
}
}
catch (Exception e)
{
Console.WriteLine(e.ToString());
}
}

private static void Send(Socket client, String data)
{

// F2 00 DATA FF

List<byte> byteTemp = new List<byte>();
byteTemp.Add(0XF2);
byteTemp.Add(0X00);


byte[] TcpData = Encoding.ASCII.GetBytes("0040005001100180");
foreach (byte eachdata in TcpData)
{
byteTemp.Add(eachdata);
}

byteTemp.Add(0XFF);

byte[] byteData = byteTemp.ToArray();




client.BeginSend(byteData, 0, byteData.Length, 0,
new AsyncCallback(SendCallback), client);
}

private static void SendCallback(IAsyncResult ar)
{
try
{
// Retrieve the socket from the state object.
Socket client = (Socket)ar.AsyncState;

// Complete sending the data to the remote device.
int bytesSent = client.EndSend(ar);
Console.WriteLine("Sent {0} bytes to server.", bytesSent);

// Signal that all bytes have been sent.
sendDone.Set();
}
catch (Exception e)
{
Console.WriteLine(e.ToString());
}
}

public static int Main(String[] args)
{
StartClient();
return 0;
}
}

Answer
private static void ReceiveCallback(IAsyncResult ar)
{     
    try
    {
        Console.WriteLine("Receieve Call Back Invoked");

        StateObject state = (StateObject)ar.AsyncState;
        Socket client = state.workSocket;

        // Read data from the remote device.
        int bytesRead = client.EndReceive(ar);
        Console.WriteLine("Receieve End Receieve");
        if (bytesRead > 0)
        {
            // There might be more data, so store the data received so far.
            state.sb.Append(Encoding.ASCII.GetString(state.buffer, 0, bytesRead));
            Console.WriteLine("Read : " + bytesRead.ToString());
            // Get the rest of the data.
            client.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0,
                new AsyncCallback(ReceiveCallback), state);
            Console.WriteLine("Begin Receieve completed");
        }
        else
        {
            // All the data has arrived; put it in response.
            if (state.sb.Length > 1)
            {
                response = state.sb.ToString();
            }
            Console.WriteLine("Received data from client");
            // Signal that all bytes have been received.
            receiveDone.Set();
        }
        Console.WriteLine("completed receive callback");
    }
    catch (Exception e)
    {
        Console.WriteLine(e.ToString());
    }
}

the data has been received, but not utilized as "else" in the above method is not getting executed.

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