question about class Socket

[Guest]

how to use Class Socket to asynchronously receive a large byte array with a
default receiveBufferSize?

the following code from msdn doesn't work:

public static void readCallback(IAsyncResult ar) {
StateObject state = (StateObject) ar.AsyncState;
Socket handler = state.WorkSocket;

// Read data from the client socket.
int read = handler.EndReceive(ar);

// Data was read from the client socket.
if (read > 0) {
state.sb.Append(Encoding.ASCII.GetString(state.buffer,0,read));
handler.BeginReceive(state.buffer,0,StateObject.BufferSize, 0,
new AsyncCallback(readCallback), state);
} else {
if (state.sb.Length > 1) {
// All the data has been read from the client;
// display it on the console.
string content = state.sb.ToString();
Console.WriteLine("Read {0} bytes from socket.\n Data : {1}",
content.Length, content);
}
handler.Close();
}
}

public class StateObject {
public Socket workSocket = null;
public const int BufferSize = 1024;
public byte[] buffer = new byte[BufferSize];
public StringBuilder sb = new StringBuilder();
}

 

[Vadym Stetsyak]

Hello, wukun!

w>how to use Class Socket to asynchronously receive a large byte array with a
w>default receiveBufferSize?

byte[] buff = new byte[receiveBufferSize];

Socket.BeginReceive(buff, ....);

w> the following code from msdn doesn't work:

Why isn't this code working, any exceptions?
Maybe instead of StringBuilder.Append(...) you should use MemoryStream.Write(...) as you want to receive binary array.

--
Regards, Vadym Stetsyak
www: http://vadmyst.blogspot.com

 

[Guest]

hello,Vadym Stetsyak:

here is the client and server code, the client send a file "c:\test.txt"
which is about 3mb bytes or larger,start the server,the client runs properly
for the first time,but at the second time the client throws an exception. try
it. thanks a lot!

/*client:*/
class TestClient
{
static void Main(string[] args)
{
// Establish the local endpoint for the socket.
IPHostEntry ipHostInfo = Dns.GetHostEntry(Dns.GetHostName());
IPAddress ipAddr = ipHostInfo.AddressList[0];
IPEndPoint ipEndPoint = new IPEndPoint(ipAddr, 11000);

// Create a TCP socket.
Socket client = new Socket(AddressFamily.InterNetwork,
SocketType.Stream, ProtocolType.Tcp);

// Connect the socket to the remote endpoint.
client.Connect(ipEndPoint);

// There is a text file test.txt located in the root directory.
string fileName = @"c:\test.txt";

// Send file fileName to remote device
Console.WriteLine("Sending {0} to the host.", fileName);
client.SendFile(fileName);

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

/*server:*/
// State object for reading client data asynchronously
public class StateObject
{
// Client socket.
public Socket workSocket = null;
// Size of receive buffer.
public const int BufferSize = 1000;
// Receive buffer.
public byte[] buffer = new byte[BufferSize];
// Received data string.
public StringBuilder sb = new StringBuilder();
}

public class AsynchronousSocketListener
{
// Thread signal.
public static ManualResetEvent allDone = new ManualResetEvent(false);

public AsynchronousSocketListener()
{
}

public static void StartListening()
{
// Data buffer for incoming data.
//byte[] bytes = new Byte[1024];

// Establish the local endpoint for the socket.
IPHostEntry ipHostInfo = Dns.GetHostEntry(Dns.GetHostName());
IPAddress ipAddress = ipHostInfo.AddressList[0];
IPEndPoint localEndPoint = new IPEndPoint(ipAddress, 11000);

// Create a TCP/IP socket.
Socket listener = new Socket(AddressFamily.InterNetwork,
SocketType.Stream, ProtocolType.Tcp);

// Bind the socket to the local endpoint and listen for incoming
connections.
try
{
listener.Bind(localEndPoint);
listener.Listen(100);

while (true)
{
// Set the event to nonsignaled state.
allDone.Reset();

// Start an asynchronous socket to listen for connections.
Console.WriteLine("Waiting for a connection...");
listener.BeginAccept(
new AsyncCallback(AcceptCallback),
listener);

// Wait until a connection is made before continuing.
allDone.WaitOne();
}

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

Console.WriteLine("\nPress ENTER to continue...");
Console.Read();

}

public static void AcceptCallback(IAsyncResult ar)
{
// Signal the main thread to continue.
allDone.Set();

// Get the socket that handles the client request.
Socket listener = (Socket)ar.AsyncState;
Socket handler = listener.EndAccept(ar);

// Create the state object.
StateObject state = new StateObject();
state.workSocket = handler;
handler.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0,
new AsyncCallback(ReadCallback), state);
}

public static void ReadCallback(IAsyncResult ar)
{
// Retrieve the state object and the handler socket
// from the asynchronous state object.
StateObject state = (StateObject)ar.AsyncState;
Socket handler = state.workSocket;

// Read data from the client socket.
int bytesRead = handler.EndReceive(ar);
state.sb.Append(Encoding.ASCII.GetString(
state.buffer, 0, bytesRead));

if (handler.Available > 0)
{
//There might be more data
handler.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0,
new AsyncCallback(ReadCallback), state);
}
else
{
// All the data has been read from the
// client. Display it on the console.
Console.WriteLine("Read {0} bytes from socket.",
state.sb.Length);
// Echo the data back to the client.
Send(handler, "Server Received ok!");
}
}

private static void Send(Socket handler, String data)
{
// Convert the string data to byte data using ASCII encoding.
byte[] byteData = Encoding.ASCII.GetBytes(data);

// Begin sending the data to the remote device.
handler.BeginSend(byteData, 0, byteData.Length, 0,
new AsyncCallback(SendCallback), handler);
}

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

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

handler.Shutdown(SocketShutdown.Both);
handler.Close();

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


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

 

[Vadym Stetsyak]

Hello, wukun!

w> here is the client and server code, the client send a file "c:\test.txt"
w> which is about 3mb bytes or larger,start the server,the client runs
w> properly for the first time,but at the second time the client throws an
w> exception. try it. thanks a lot!

What exception does it throw?

The ReadCallback isn't doing what it has to do.
In your case you have to call BeginReceive until receive 0 or exception.

There can be situation when handler.Available will be equal to 0, because data has not yet arrived to the host ( it is still on the wire ).

the code may look like this
try
{
int bytesRead = handler.EndReceive(ar);
if ( bytesRead == 0 )
//we have data end

}
catch
{
smth happened, stop receiving data.
}

--
Regards, Vadym Stetsyak
www: http://vadmyst.blogspot.com

 

[Guest]

thank you very much!

the two code fragments at the end of this letter are from msdn, they work
correctly, but can I receive all binary data without depending on the "<EOF>"
tag.

according to your advice, I change the 'ReadCallback' method of the Server
to this:

public static void ReadCallback(IAsyncResult ar) {
String content = String.Empty;

// Retrieve the state object and the handler socket
// from the asynchronous state object.
StateObject state = (StateObject) ar.AsyncState;
Socket handler = state.workSocket;

try
{
// Read data from the client socket.
int bytesRead = handler.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));
// Not all data received. Get more.
handler.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0,
new AsyncCallback(ReadCallback), state);
}
else
{
// All the data has been read from the
// client. Display it on the console.
Console.WriteLine("Read {0} bytes from socket.",
content.Length );
// Echo the data back to the client.
Send(handler, "Server Received OK!");
}
catch
{
return;
}
}

if the client code use method SendFile(),the server receive data correctly,
but if the client code send data asynchronously, just like the code in this
letter, it doesn't work too. tell me what's wrong.

take you so much time, great thanks!

Regards! wukun

/*Client*/
using System;
using System.Net;
using System.Net.Sockets;
using System.Threading;
using System.Text;

// 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 = 11000;

// 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
{
// Establish the local endpoint for the socket.
IPHostEntry ipHostInfo = Dns.Resolve(Dns.GetHostName());
IPAddress ipAddress = ipHostInfo.AddressList[0];
IPEndPoint remoteEP = new IPEndPoint(ipAddress, 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
{
// Retrieve the state object and the client socket
// from the asynchronous state object.
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)
{
// Convert the string data to byte data using ASCII encoding.
byte[] byteData = Encoding.ASCII.GetBytes(data);

// Begin sending the data to the remote device.
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;
}
}

/*Server*/
using System;
using System.Net;
using System.Net.Sockets;
using System.Text;
using System.Threading;

// State object for reading client data asynchronously
public class StateObject {
// Client socket.
public Socket workSocket = null;
// Size of receive buffer.
public const int BufferSize = 1024;
// Receive buffer.
public byte[] buffer = new byte[BufferSize];
// Received data string.
public StringBuilder sb = new StringBuilder();
}

public class AsynchronousSocketListener {
// Thread signal.
public static ManualResetEvent allDone = new ManualResetEvent(false);

public AsynchronousSocketListener() {
}

public static void StartListening() {
// Data buffer for incoming data.
byte[] bytes = new Byte[1024];

// Establish the local endpoint for the socket.
// The DNS name of the computer
// running the listener is "host.contoso.com".
IPHostEntry ipHostInfo = Dns.Resolve(Dns.GetHostName());
IPAddress ipAddress = ipHostInfo.AddressList[0];
IPEndPoint localEndPoint = new IPEndPoint(ipAddress, 11000);

// Create a TCP/IP socket.
Socket listener = new Socket(AddressFamily.InterNetwork,
SocketType.Stream, ProtocolType.Tcp );

// Bind the socket to the local endpoint and listen for incoming
connections.
try {
listener.Bind(localEndPoint);
listener.Listen(100);

while (true) {
// Set the event to nonsignaled state.
allDone.Reset();

// Start an asynchronous socket to listen for connections.
Console.WriteLine("Waiting for a connection...");
listener.BeginAccept(
new AsyncCallback(AcceptCallback),
listener );

// Wait until a connection is made before continuing.
allDone.WaitOne();
}

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

Console.WriteLine("\nPress ENTER to continue...");
Console.Read();

}

public static void AcceptCallback(IAsyncResult ar) {
// Signal the main thread to continue.
allDone.Set();

// Get the socket that handles the client request.
Socket listener = (Socket) ar.AsyncState;
Socket handler = listener.EndAccept(ar);

// Create the state object.
StateObject state = new StateObject();
state.workSocket = handler;
handler.BeginReceive( state.buffer, 0, StateObject.BufferSize, 0,
new AsyncCallback(ReadCallback), state);
}

public static void ReadCallback(IAsyncResult ar) {
String content = String.Empty;

// Retrieve the state object and the handler socket
// from the asynchronous state object.
StateObject state = (StateObject) ar.AsyncState;
Socket handler = state.workSocket;

// Read data from the client socket.
int bytesRead = handler.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));

// Check for end-of-file tag. If it is not there, read
// more data.
content = state.sb.ToString();
if (content.IndexOf("<EOF>") > -1) {
// All the data has been read from the
// client. Display it on the console.
Console.WriteLine("Read {0} bytes from socket. \n Data : {1}",
content.Length, content );
// Echo the data back to the client.
Send(handler, content);
} else {
// Not all data received. Get more.
handler.BeginReceive(state.buffer, 0,
StateObject.BufferSize, 0,
new AsyncCallback(ReadCallback), state);
}
}
}

private static void Send(Socket handler, String data) {
// Convert the string data to byte data using ASCII encoding.
byte[] byteData = Encoding.ASCII.GetBytes(data);

// Begin sending the data to the remote device.
handler.BeginSend(byteData, 0, byteData.Length, 0,
new AsyncCallback(SendCallback), handler);
}

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

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

handler.Shutdown(SocketShutdown.Both);
handler.Close();

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


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

 

[Vadym Stetsyak]

Hello, wukun!

w> the two code fragments at the end of this letter are from msdn, they
w> work correctly, but can I receive all binary data without depending on
w> the "<EOF>" tag.

Sender must somehow specify that he sent all the data, right?
Sender can either close connection after send is completed or establish some special format of data, that
receiver will understand ( in this case connection can remain opened ).

w> if the client code use method SendFile(),the server receive data
w> correctly, but if the client code send data asynchronously, just like
w> the code in this letter, it doesn't work too. tell me what's wrong.

What do you mean by 'doesn't work too'? Any exceptions, errors?

Describe the problem more precisely...

--
Regards, Vadym Stetsyak
www: http://vadmyst.blogspot.com

 

[Guest]

thank you very much!

run the following code, the client send a test string, but it doesn't
receive server's response, no exception.

the server doesn't show that it has received any data, and the client
doesn't show that it has received any response. they seem stop execution
silently.

I have very little knowledge about network programming. Taking you so much
time, great thanks.

Regards! wukun

/*Client*/
using System;
using System.Net;
using System.Net.Sockets;
using System.Threading;
using System.Text;

// 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 = 11000;

// 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
{
// Establish the local endpoint for the socket.
IPHostEntry ipHostInfo = Dns.Resolve(Dns.GetHostName());
IPAddress ipAddress = ipHostInfo.AddressList[0];
IPEndPoint remoteEP = new IPEndPoint(ipAddress, 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
{
// Retrieve the state object and the client socket
// from the asynchronous state object.
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)
{
// Convert the string data to byte data using ASCII encoding.
byte[] byteData = Encoding.ASCII.GetBytes(data);

// Begin sending the data to the remote device.
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;
}
}

/*Server*/
using System;
using System.Net;
using System.Net.Sockets;
using System.Text;
using System.Threading;

// State object for reading client data asynchronously
public class StateObject
{
// Client socket.
public Socket workSocket = null;
// Size of receive buffer.
public const int BufferSize = 1024;
// Receive buffer.
public byte[] buffer = new byte[BufferSize];
// Received data string.
public StringBuilder sb = new StringBuilder();
}

public class AsynchronousSocketListener
{
// Thread signal.
public static ManualResetEvent allDone = new ManualResetEvent(false);

public AsynchronousSocketListener()
{
}

public static void StartListening() {
// Data buffer for incoming data.
byte[] bytes = new Byte[1024];

// Establish the local endpoint for the socket.
// The DNS name of the computer
// running the listener is "host.contoso.com".
IPHostEntry ipHostInfo = Dns.Resolve(Dns.GetHostName());
IPAddress ipAddress = ipHostInfo.AddressList[0];
IPEndPoint localEndPoint = new IPEndPoint(ipAddress, 11000);

// Create a TCP/IP socket.
Socket listener = new Socket(AddressFamily.InterNetwork,
SocketType.Stream, ProtocolType.Tcp );

// Bind the socket to the local endpoint and listen for incoming
//connections.
try {
listener.Bind(localEndPoint);
listener.Listen(100);

while (true) {
// Set the event to nonsignaled state.
allDone.Reset();

// Start an asynchronous socket to listen for connections.
Console.WriteLine("Waiting for a connection...");
listener.BeginAccept(
new AsyncCallback(AcceptCallback),
listener );

// Wait until a connection is made before continuing.
allDone.WaitOne();
}

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

Console.WriteLine("\nPress ENTER to continue...");
Console.Read();

}

public static void AcceptCallback(IAsyncResult ar)
{
// Signal the main thread to continue.
allDone.Set();

// Get the socket that handles the client request.
Socket listener = (Socket)ar.AsyncState;
Socket handler = listener.EndAccept(ar);

// Create the state object.
StateObject state = new StateObject();
state.workSocket = handler;
handler.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0,
new AsyncCallback(ReadCallback), state);
}

public static void ReadCallback(IAsyncResult ar) {
String content = String.Empty;

// Retrieve the state object and the handler socket
// from the asynchronous state object.
StateObject state = (StateObject) ar.AsyncState;
Socket handler = state.workSocket;

try
{
// Read data from the client socket.
int bytesRead = handler.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));
// Not all data received. Get more.
handler.BeginReceive(state.buffer, 0,
StateObject.BufferSize, 0,
new AsyncCallback(ReadCallback), state);
}
else
{
// All the data has been read from the
// client. Display it on the console.
Console.WriteLine("Read {0} bytes from socket.",
content.Length);
// Echo the data back to the client.
Send(handler, "Server Received OK!");
}
}
catch
{
return;
}
}

private static void Send(Socket handler, String data)
{
// Convert the string data to byte data using ASCII encoding.
byte[] byteData = Encoding.ASCII.GetBytes(data);

// Begin sending the data to the remote device.
handler.BeginSend(byteData, 0, byteData.Length, 0,
new AsyncCallback(SendCallback), handler);
}

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

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

handler.Shutdown(SocketShutdown.Both);
handler.Close();

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


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