WPF Client Server Login Application, C# source code

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WPF

Hello Everyone

I have created a Client / Server Login application in WPF. When I execute the server application it waits for the client to connect, then when I execute the Client application and I try to enter the password and I click the login button it gives me an error saying...

System.NullReferenceException..

I'm stuck and im very new to this WPF, If someone can help me on this I would appritiated a lot

This is the Code for Server class...

<pre lang="msil">using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;
using System.Timers;
using System.Threading;
using System.Net.Sockets;
using System.IO;
using System.Windows.Threading;
using System.Collections;
using System.ComponentModel;
using System.Windows.Controls.Primitives;

namespace DtposServer
{
  // This stores data about each client ClientData
  public struct ClientData
  {
    public Socket structSocket;
    public Thread structThread;
  }
  /// <summary>
  /// Interaction logic for TCPServer.xaml
  /// </summary>
  public partial class TCPServer : Window
  {
    private System.Timers.Timer clockTimer;
    //===================================\\
    private StatusBar statusBar1 = new StatusBar();
    private TcpListener tcpLsn;
    private Hashtable ht = new Hashtable();
    private static Int32 connectId = 0;
    private Thread tcpThd;
    private string ipAddress = "0.0.0.0";
    //private System.ComponentModel.IContainer components;
    public TCPServer()
    {
      InitializeComponent();
      clockTimer = new System.Timers.Timer(1000);
      clockTimer.Elapsed += new ElapsedEventHandler(clockTimer_Elapsed);
      clockTimer.Start();
      DataContext = this;
      // ============================================================ \\
      tcpLsn = new TcpListener(System.Net.IPAddress.Parse(ipAddress), 8000);
      tcpLsn.Start();
      txtBlock1.Text = "IP Address listen at: " + "   " + tcpLsn.LocalEndpoint.ToString();
      tcpThd = new Thread(WaitingForClient);
      tcpThd.Start();
    }
    void clockTimer_Elapsed(object sender, ElapsedEventArgs e)
    {
      Dispatcher.BeginInvoke(new Action(UpdateCurrentDateTime));
    }
    #region " Server Waiting For Client To Connect "
    // Waiting For Client
    public void WaitingForClient()
    {
      ClientData CData = default(ClientData);
      while (true)
      {
        // Accept will block until someone connects
        CData.structSocket = tcpLsn.AcceptSocket();
        Interlocked.Increment(ref connectId);
        CData.structThread = new Thread(ReadSocket);
        lock (this)
        {
          //It is used to keep connected Sockets and active thread
          ht.Add(connectId, CData);
          updateDataGrid(("Connection accepted."));
          updateDataGrid(("Connected User: > " + connectId + " Time: " + DateTime.Now.ToLongTimeString()));
          updateDataGrid(("---------------------------------------------"));
        }
        CData.structThread.Start();
      }
    }
    #endregion
    #region " Server Read Socket When Client Connects "
    //Read Socket
    public void ReadSocket()
    {
        //Real-Id will not be changed for each thread, but connectId is
        //changed. It can not be used to delete object from Hashtable
        Int32 realId = connectId;
        Byte[] receive = null;
        ClientData cd = (ClientData)dataHolder(realId);
        Socket s = cd.structSocket;
        int ret = 0;
        while (true)
      {
            if (s.Connected)
        {
                receive = new Byte[100];
                try
          {
                    //Receive will block until data coming ret is 0 or Exception
                    //will happen when Socket connection is broken
                    ret = s.Receive(receive, receive.Length, 0);
                    if (ret > 0)
            {
                        //ClientData clntData = new ClientData();
                        foreach (ClientData clntData in ht.Values)
              {
                            if (clntData.structSocket.Connected)
                {
                                clntData.structSocket.Send(receive, ret, SocketFlags.None);
                            }
                        }
            }
                    else
            {
                        break; // TODO: might not be correct. Was : Exit While
                    }
                }
          catch (Exception e)
          {
                    updateDataGrid(e.ToString());
                    if (!s.Connected)
            {
                        break; // TODO: might not be correct. Was : Exit While
                    }
                }
            }
        }
        CloseTheThread(realId);
    }
    #endregion
    #region " Server Closing The Thread "
    // Close The Thread
    private void CloseTheThread(long realId)
    {
      try
      {
        ClientData cd = (ClientData)dataHolder(realId);
        cd.structThread.Abort();
      }
      catch (Exception)
      {
        lock (this)
        {
          ht.Remove(realId);
          updateDataGrid(("Disconnected User: > " + realId + " Time: " + DateTime.Now.ToLongTimeString()));
        }
      }
    }
    private ClientData dataHolder(long realId)
    {
      throw new NotImplementedException();
    }
    #endregion
    #region " Server Updating The Data Grid "
    // Update Data Grid
    public void updateDataGrid(string displayString)
    {
      txtServerConnection.AppendText((displayString)); // + ControlChars.Cr + ControlChars.Lf));
    }
    #endregion
    [BrowsableAttribute(false)]
    public static bool CheckForIllegalCrossThreadCalls { get; set; }
    private void TCPSerever_Loaded(object sender, RoutedEventArgs e)
    {
      CanvasBorder.BorderThickness = new Thickness(1);
      lblDate.Content += DateTime.Today.DayOfWeek + ", " + DateTime.Now.ToLongDateString();
      //This is a snippet to hold the control of the illegal Cross-Thread call operation
      CheckForIllegalCrossThreadCalls = false;
      //===============================================
      txtServerConnection.Text = "Wating for connection... ";
    }
    public string CurrentDateTime
    {
      get { return (string)GetValue(CurrentDateTimeProperty); }
      set { SetValue(CurrentDateTimeProperty, value); }
    }
    public static readonly DependencyProperty CurrentDateTimeProperty =
      DependencyProperty.Register("CurrentDateTime", typeof(string), typeof(TCPServer), new UIPropertyMetadata(string.Empty));
    private void UpdateCurrentDateTime()
    {
      CurrentDateTime = DateTime.Now.ToShortTimeString();
    }
    private void btnExit_Click(object sender, RoutedEventArgs e)
    {
      if ((tcpLsn != null))
      {
            tcpLsn.Stop();
        }
        //ClientData cd = default(ClientData);
      foreach (ClientData cd in ht.Values)
      {
            if (cd.structSocket.Connected)
        {
                cd.structSocket.Close();
            }
            if (cd.structThread.IsAlive)
        {
                cd.structThread.Abort();
            }
        }
        if (tcpThd.IsAlive)
      {
            tcpThd.Abort();
        }
        this.Close();
    }
  }
}

This is the code for Client class...

using System;
using System.Collections;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Data.OleDb;
using System.IO;
using System.Linq;
using System.Net.Sockets;
using System.Text;
using System.Threading;
using System.Timers;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Controls.Primitives;
using System.Windows.Data;
//using System.Windows.Documents;
using System.Windows.Input;
//using System.Windows.Media;
//using System.Windows.Media.Imaging;
//using System.Windows.Navigation;
//using System.Windows.Shapes;
using System.Windows.Threading;
using System.Data.Common;

namespace DtposClient
{
  /// <summary>
  /// Interaction logic for TCPClient.xaml
  /// </summary>
  public partial class TCPClient : Window
  {
    public Thread tcpThd;
    public byte[] readBuffer;
    public byte[] writeBuffer;
    public Stream stream;
    public Socket socket;
    public TcpClient tcpclnt;
    public int password;
    //===============================\\

    public OleDbConnection connection = new OleDbConnection();
    
    DataSet DtposMenuDS = new DataSet();
    OleDbCommand command = new OleDbCommand();
    OleDbDataAdapter dtadapter = new OleDbDataAdapter();
    public OleDbDataReader dataReader;
    
    private ClientLogin loginForm = new ClientLogin();

    public TCPClient()
    {
      InitializeComponent();
      connection.ConnectionString = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:\\Users\\AP_AE\\Desktop\\DTPOS_ClientServer\\DataBase\\DtposMenu.accdb;";
      //connection = new OleDbConnection(connectionString);

      try
      {
        connection.Open();
      }
      catch (Exception ex)
      {
        MessageBox.Show("Error Masseage = " + ex.Message);
      }
      if (connection.State != ConnectionState.Open)
      {
        MessageBox.Show("Database Connection Failed to Open");
        //Application.Exit();
        this.Close();
      }
    }

    #region " Client, Start Server - (Client User is Connecting To Server) "

    public void startServer(string ipAddress, int portNumber, int password)
    {
      try
      {
        connection.Open();
        dtadapter.SelectCommand.CommandText = "SELECT * FROM Users WHERE Password = '" + password + "';";
        //string commandString = "SELECT Password FROM [Users]";
        //commandString += "WHERE(Password=@Param1)";
        //OleDbDataAdapter dtadapter = new OleDbDataAdapter();
        //DataTable myDataTable = new DataTable();
        //OleDbCommand comm = new OleDbCommand();
        dataReader = dtadapter.SelectCommand.ExecuteReader();
        //comm.Connection = connection;
        //comm.CommandType = CommandType.Text;
        //comm.CommandText = commandString;
        //comm.Parameters.Add("@Param1", OleDbType.Integer, 4).Value = txtPassword.Text;
        //dtadapter.SelectCommand = comm;
        //dtadapter.Fill(myDataTable);
        dataReader.Read();

        this.password = password;
        tcpclnt = new TcpClient();
        tcpclnt.Connect(ipAddress.Trim(), portNumber);

        txtLoginWindow.AppendText("Connecting to server... " + "\n" + "======================================== " + "\n");
        stream = tcpclnt.GetStream();
        Thread.Sleep(4000);
        txtLoginWindow.AppendText((" Hello " + dataReader["Name"].ToString() + ", " + " You have logged in as " + "'" + dataReader["Access Level"].ToString() + "'" + " Welcome to DTPOS System"));
        tcpThd = new Thread(ReadSocket);
        //tcpThd.Name = loginName
        tcpThd.Start();
        
        dataReader.Close();
      }
      catch (Exception ex)
      {
        //MessageBox.Show(ex.StackTrace);
        MessageBox.Show(ex.ToString(), "Unable to open database!");
      }
      connection.Close();

    }
    
    #endregion

    #region " Client Read Socket "

    public void ReadSocket()
    {
      while (true)
      {
        try
        {
          readBuffer = new Byte[101];
          stream.Read(readBuffer, 0, 100);

          // If the text box exceeds the maximum lenght, then get
          // remove the top part of the text
          if (txtLoginWindow.Text.Length > txtLoginWindow.MaxLength)
          {
            txtLoginWindow.Select(0, 300);
            txtLoginWindow.SelectedText = "";
          }
          txtLoginWindow.AppendText((System.Text.Encoding.ASCII.GetString(readBuffer)));
        }
        catch (Exception)
        {
          break; // TODO: might not be correct. Was : Exit While
        }
      }
    }
    
    #endregion

    #region " User Client Write To Server "

    public void writeToServer(string strn)
    {
      System.Text.ASCIIEncoding encord = new System.Text.ASCIIEncoding();
      writeBuffer = encord.GetBytes(strn);
      if ((stream != null))
      {
        stream.Write(writeBuffer, 0, writeBuffer.Length);
      }
    }
    
    #endregion

    private void menuItemStart_Click(object sender, RoutedEventArgs e)
    {
      loginForm = new ClientLogin();
      //loginForm.ShowDialog();
      loginForm.infoChecker(this);
    }

    private void menuItemExit_Click(object sender, RoutedEventArgs e)
    {
      this.Close();
    }

    private void btnLogout_Click(object sender, EventArgs e)
    {
      txtLoginWindow.AppendText(("Logging out from the server!!!"));
      Thread.Sleep(3000);
      //dataReader = new System.Data.OleDb.OleDbDataReader();
      txtLoginWindow.AppendText(("User: " + dataReader["Name"].ToString() + " as " + dataReader["Access Level"].ToString() + " Has Logged Out... "));
      this.btnLogout.IsEnabled = false;
      //writeToServer((loginName & " has logged out... "));
      if ((tcpThd != null) & tcpThd.IsAlive) 
      {
	      tcpThd.Abort();
      }
      if ((stream != null)) 
      {
	      stream.Close();
      }
      if ((tcpclnt != null))
      {
	      tcpclnt.Close();
      }
    }
  }
}

This is the code for Client Login class....

using System;
using System.Collections;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Data.OleDb;
using System.IO;
using System.Linq;
using System.Net.Sockets;
using System.Text;
using System.Threading;
using System.Timers;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Controls.Primitives;
using System.Windows.Data;
//using System.Windows.Documents;
using System.Windows.Input;
//using System.Windows.Media;
//using System.Windows.Media.Imaging;
//using System.Windows.Navigation;
//using System.Windows.Shapes;
using System.Windows.Threading;
using System.Data.Common;

namespace DtposClient
{
  /// <summary>
  /// Interaction logic for ClientLogin.xaml
  /// </summary>
  public partial class ClientLogin : Window
  {
    TCPClient tcpclient;// = new TCPClient();
    //==================================\\
    DataSet DtposMenuDS = new DataSet();
    
    public OleDbConnection connection = new OleDbConnection();
    
    //public TextBox txtIPaddress = new System.Windows.Controls.TextBox();
    //public TextBox txtPortNumber = new System.Windows.Controls.TextBox();
    
    public ClientLogin()
    {
      InitializeComponent();
      connection.ConnectionString = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:\\Users\\AP_AE\\Desktop\\DTPOS_ClientServer\\DataBase\\DtposMenu.accdb;";
      //connection = new OleDbConnection(connectionString);

      /*try
      {
        connection.Open();
      }
      catch (Exception ex)
      {
        MessageBox.Show("DataBase Access Error");
        MessageBox.Show("Error Masseage = " + ex.Message);
      }
      
      if (connection.State != ConnectionState.Open)
      {
        MessageBox.Show("Database Connection Failed to Open");
        //Application.Exit();
        this.Close();
      }*/
    }

    public void infoChecker(TCPClient formOne)
    {
      this.tcpclient = formOne;
      this.ShowDialog();
    }

    private void btnLogin_Click(object sender, RoutedEventArgs e)
    {
      try
      {
        connection.Open();
        if (txtPassword.Text.Length == 0)
        {
          OleDbCommand command = new OleDbCommand();
    
          OleDbDataAdapter dtadapter = new OleDbDataAdapter();
          OleDbDataReader dataReader;
          
          dtadapter.SelectCommand.CommandText = "SELECT * FROM [Users] WHERE Password = '" + txtPassword.Text + "'";
          dataReader = dtadapter.SelectCommand.ExecuteReader();
          dataReader.Read();

          MessageBox.Show(" You have loged as: - " + dataReader["Access Level"].ToString() + " Welcome " + dataReader["Name"].ToString() + " to DTPOS System ", "Login Successful", MessageBoxButton.OK, MessageBoxImage.Information);
          UserLoginModule.UserAccessLevel = dataReader["Access Level"].ToString();
          UserLoginModule.UserName = dataReader["Name"].ToString();

          //ToDo: Error processing original source shown below
          //--^--- Unexpected pre-processor directive
          this.tcpclient.startServer(txtIpAddress.Text.ToString().Trim(), Convert.ToInt32(txtPortNumber.Text.ToString().Trim()), Convert.ToInt32(txtPassword.Text.ToString().Trim()));
          // Always call Close when done reading.
          
          dataReader.Close();
          connection.Close();
          this.Close();
          
        }
        else if (txtPassword.Text.Length < 4)
        {
          MessageBox.Show("You must enter data in order to proceed further. Please try again...", "Error: Non Data Entry", MessageBoxButton.OK, MessageBoxImage.Information);
          txtPassword.Focus();
        }

      }
      catch (Exception ex)
      {
        MessageBox.Show(ex.StackTrace);
        MessageBox.Show(ex.ToString(), "Unable to open database!");
      }
      // Display error if unable to open database
      
      
    }

    private void btnCancel_Click(object sender, RoutedEventArgs e)
    {
      this.Close();
    }

    private void btnReset_Click(object sender, RoutedEventArgs e)
    {
      txtPassword.Clear();
      txtPassword.Focus();
    }

  }
}

This is the code for UserClient property class...

using System;
using System.Collections;
using System.Collections.Generic;
using System.Data;
using System.Diagnostics;
namespace DtposClient
{
  public class UserClient
  {
    // User Client Global variables
      // ====================================
    public string UserName;
    public string UserAccessLevel;
    public int UserPassword;
      public string fullName
    {
          get { return UserName; }
          set { UserName = value; }
      }
    public string accLevel
    {
      get { return UserAccessLevel; }
      set { UserAccessLevel = value; }
    }
      public int userPass
    {
      get { return UserPassword; }
      set { UserPassword = value; }
      }
      public override bool Equals(object obj)
      {
      UserClient temp = obj as UserClient;
      if (temp != null)
      {
        return (userPass == temp.userPass);
      }
      return false;
      }
    public UserClient(string fullNam, string aLevel, int pass)
      {
          fullName = fullNam;
      accLevel = aLevel;
      userPass = pass;
      }
  }
}

And finally this is a static UserLoginModule class...

using System;
using System.Collections;
using System.Collections.Generic;
using System.Data;
using System.Diagnostics;
namespace DtposClient
{
  static class UserLoginModule
  {
    public static ArrayList UserClientList = new ArrayList();
    public static System.Collections.Hashtable ordersMap = new Hashtable();
    // Global variables
    public static string UserName;
    public static string UserAccessLevel;
    public static int UserPassword = 0;
    public static UserClient CurrUserClient = null;
  }
}

thanks in advance

kind regards

roni