C#

public class form2 : Form
{
   //publish a FormChanged event
   public event EventHandler FormChanged;
   ...
   ...
   protected void SomeClassThatChangesForm2()
   {
   ...
   ...
      //we just did something that changed this form, so
      //we'll fire the FormChanged event to inform subscribers
      if( FormChanged != null ) //if we have subscribers
         FormChanged( this, new EventArgs() ) //fire the event
   ...
   }
   ...
}

public class form1 : Form
{
   ...
   ...
   protected void Form2ChangedHandler( object sender, EventArgs e )
   {
      //if we are in this handler, it means that we've 
      //recieved the FormChanged event 
      ...
      //deal with the event
      ...
   }
   ...
   ...
   //constructor
   public form1()
   {
      ...
      //subscribe to form2's event, specifying the handler
      //as the protected Form2ChangedHandler method
      this.form2.FormChanged += 
         new EventHandler( Form2ChangedHandler );
      ...
   }
   ...
}

public static int Convert.ToInt32(string value) {
	if (value == null)
		return 0;
	return Int32.Parse(value);
}

public class MyTcpClient : System.Net.Sockets.TcpClient
{
  public MyTcpClient()
  {
  }

  public bool Connected
  {
    get
    {
      return Client.Connected;
    }
  }
}

static void Main(string[] args)
{
  TcpClient tcpClient = new TcpClient("localhost",3000);
  NetworkStream ns = tcpClient.GetStream();
  byte[] bytesOut = 	Encoding.Unicode.GetBytes("disconnect_me");
  ns.Write(bytesOut,0,bytesOut.Length);

  //now the server has closed TCP connection on its behalf
  //but the client tries to write something again. 
  //I think that some exception should be thrown at furher usage of 
  //the stream, or at least some fields should indicate that the 
  //remote side has ended the connection. 
  //The netstat application correctly identifies the situation 
  //(now instead of "established" , the connection is in 
  //CLOSE_WAIT state) BUT NO ERROR IS REPORTED WHEN  I WRITE TO (or 
  //read from) THE STREAM...
  ns.Write(bytesOut,0,bytesOut.Length);
}

static void Main(string[] args)
  {
  TcpListener listener = new TcpListener(3000);
  listener.Start();
  Console.WriteLine("The server is listening..");
  TcpClient tcpClient = listener.AcceptTcpClient();
  Console.WriteLine("Some client has connected to the server..");
  NetworkStream ns = tcpClient.GetStream();

  bool listening=true;
  const int MaxSize=100;
  int bytesRead=0;
  byte[] buffer = new Byte[MaxSize];
  while(listening)
  {
	bytesRead = ns.Read(buffer,0,MaxSize);
	string command = Encoding.Unicode.GetString(buffer,0,bytesRead);
	if(command.CompareTo("disconnect_me")==0)
	{
		Console.WriteLine("Client wants to be disconnected");
		listening=false;
	}
  }
  ns.Close(); //now close the stream and TCP connection
  tcpClient.Close();
  Console.WriteLine("The connection with client has been closed.");
  Console.ReadLine();
}