Client/Server Tic-Tac-Toe Using a Multithreaded Server

1 // Fig. 23.5: TicTacToeServer.cs 2 // This class maintains a game of Tic-Tac-Toe for two 3 // client applications. 4 using System; 5 using System.Windows.Forms; 6 using System.Net; 7 using System.Net.Sockets; 8 using System.Threading; 9 using System.IO; 10 11 public partial class TicTacToeServerForm : Form 12 { 13 public TicTacToeServerForm() 14 { 15 InitializeComponent(); 16 } // end constructor 17 18 private byte[] board; // the local representation of the game board 19 private Player[] players; // two Player objects 20 private Thread[] playerThreads; // Threads for client interaction 21 private TcpListener listener; // listen for client connection 22 private int currentPlayer; // keep track of whose turn it is 23 private Thread getPlayers; // Thread for acquiring client connections 24 internal bool disconnected = false; // true if the server closes 25 26 // initialize variables and thread for receiving clients 27 private void TicTacToeServerForm_Load( object sender, EventArgs e ) 28 { 29 board = new byte[ 9 ]; 30 players = new Player[ 2 ]; 31 playerThreads = new Thread[ 2 ]; 32 currentPlayer = 0; 33 34 // accept connections on a different thread 35 getPlayers = new Thread( new ThreadStart( SetUp ) ); 36 getPlayers.Start(); 37 } // end method TicTacToeServerForm_Load 38 39 // notify Players to stop Running 40 private void TicTacToeServerForm_FormClosing( object sender, 41 FormClosingEventArgs e ) 42 { 43 disconnected = true; 44 System.Environment.Exit( System.Environment.ExitCode ); 45 } // end method TicTacToeServerForm_FormClosing 46 47 // delegate that allows method DisplayMessage to be called 48 // in the thread that creates and maintains the GUI 49 private delegate void DisplayDelegate( string message ); 50 51 // method DisplayMessage sets displayTextBox's Text property 52 // in a thread-safe manner 53 internal void DisplayMessage( string message ) 54 { 55 // if modifying displayTextBox is not thread safe 56 if ( displayTextBox.InvokeRequired ) 57 { 58 // use inherited method Invoke to execute DisplayMessage 59 // via a delegate 60 Invoke( new DisplayDelegate( DisplayMessage ), 61 new object[] { message } ); 62 } // end if 63 else // OK to modify displayTextBox in current thread 64 displayTextBox.Text += message; 65 } // end method DisplayMessage 66 67 // accepts connections from 2 players 68 public void SetUp() 69 { 70 DisplayMessage( "Waiting for players... " ); 71 72 // set up Socket 73 listener = 74 new TcpListener( IPAddress.Parse( "127.0.0.1" ), 50000 ); 75 listener.Start(); 76 77 // accept first player and start a player thread 78 players[ 0 ] = new Player( listener.AcceptSocket(), this, 0 ); 79 playerThreads[ 0 ] = 80 new Thread( new ThreadStart( players[ 0 ].Run ) ); 81 playerThreads[ 0 ].Start(); 82 83 // accept second player and start another player thread 84 players[ 1 ] = new Player( listener.AcceptSocket(), this, 1 ); 85 playerThreads[ 1 ] = 86 new Thread( new ThreadStart( players[ 1 ].Run ) ); 87 playerThreads[ 1 ].Start(); 88 89 // let the first player know that the other player has connected 90 lock ( players[ 0 ] ) 91 { 92 players[ 0 ].threadSuspended = false; 93 Monitor.Pulse( players[ 0 ] ); 94 } // end lock 95 } // end method SetUp 96 97 // determine if a move is valid 98 public bool ValidMove( int location, int player ) 99 { 100 // prevent another thread from making a move 101 lock ( this ) 102 { 103 // while it is not the current player's turn, wait 104 while ( player != currentPlayer ) 105 Monitor.Wait( this ); 106 107 // if the desired square is not occupied 108 if ( !IsOccupied( location ) ) 109 { 110 // set the board to contain the current player's mark 111 board[ location ] = ( byte ) ( currentPlayer == 0 ? 112 'X' : 'O' ); 113 114 // set the currentPlayer to be the other player 115 currentPlayer = ( currentPlayer + 1 ) % 2; 116 117 // notify the other player of the move 118 players[ currentPlayer ].OtherPlayerMoved( location ); 119 120 // alert the other player that it's time to move 121 Monitor.Pulse( this ); 122 return true; 123 } // end if 124 else 125 return false; 126 } // end lock 127 } // end method ValidMove 128 129 // determines whether the specified square is occupied 130 public bool IsOccupied( int location ) 131 { 132 if ( board[ location ] == 'X' || board[ location ] == 'O' ) 133 return true; 134 else 135 return false; 136 } // end method IsOccupied 137 138 // determines if the game is over 139 public bool GameOver() 140 { 141 // place code here to test for a winner of the game 142 return false; 143 } // end method GameOver 144 } // end class TicTacToeServerForm 145 146 // class Player represents a tic-tac-toe player 147 public class Player 148 { 149 internal Socket connection; // Socket for accepting a connection 150 private NetworkStream socketStream; // network data stream 151 private TicTacToeServerForm server; // reference to server 152 private BinaryWriter writer; // facilitates writing to the stream 153 private BinaryReader reader; // facilitates reading from the stream 154 private int number; // player number 155 private char mark; // player's mark on the board 156 internal bool threadSuspended = true; // if waiting for other player 157 158 // constructor requiring Socket, TicTacToeServerForm and int 159 // objects as arguments 160 public Player( Socket socket, TicTacToeServerForm serverValue, 161 int newNumber ) 162 { 163 mark = (newNumber == 0 ? 'X' : 'O'); 164 connection = socket; 165 server = serverValue; 166 number = newNumber; 167 168 // create NetworkStream object for Socket 169 socketStream = new NetworkStream( connection ); 170 171 // create Streams for reading/writing bytes 172 writer = new BinaryWriter( socketStream ); 173 reader = new BinaryReader( socketStream ); 174 } // end constructor 175 176 // signal other player of move 177 public void OtherPlayerMoved( int location ) 178 { 179 // signal that opponent moved 180 writer.Write( "Opponent moved." ); 181 writer.Write( location ); // send location of move 182 } // end method OtherPlayerMoved 183 184 // allows the players to make moves and receive moves 185 // from the other player 186 public void Run() 187 { 188 bool done = false; 189 190 // display on the server that a connection was made 191 server.DisplayMessage( "Player " + ( number == 0 ? 'X' : 'O' ) 192 + " connected " ); 193 194 // send the current player's mark to the client 195 writer.Write( mark ); 196 197 // if number equals 0 then this player is X, 198 // otherwise O must wait for X's first move 199 writer.Write( "Player " + ( number == 0 ? 200 "X connected. " : "O connected, please wait. " ) ); 201 202 // X must wait for another player to arrive 203 if ( mark == 'X' ) 204 { 205 writer.Write( "Waiting for another player." ); 206 207 // wait for notification from server that another 208 // player has connected 209 lock ( this ) 210 { 211 while ( threadSuspended ) 212 Monitor.Wait( this ); 213 } // end lock 214 215 writer.Write( "Other player connected. Your move." ); 216 } // end if 217 218 // play game 219 while ( !done ) 220 { 221 // wait for data to become available 222 while ( connection.Available == 0 ) 223 { 224 Thread.Sleep( 1000 ); 225 226 if ( server.disconnected ) 227 return; 228 } // end while 229 230 // receive data 231 int location = reader.ReadInt32(); 232 233 // if the move is valid, display the move on the 234 // server and signal that the move is valid 235 if ( server.ValidMove( location, number ) ) 236 { 237 server.DisplayMessage( "loc: " + location + " " ); 238 writer.Write( "Valid move." ); 239 } // end if 240 else // signal that the move is invalid 241 writer.Write( "Invalid move, try again." ); 242 243 // if game is over, set done to true to exit while loop 244 if ( server.GameOver() ) 245 done = true; 246 } // end while loop 247 248 // close the socket connection 249 writer.Close(); 250 reader.Close(); 251 socketStream.Close(); 252 connection.Close(); 253 } // end method Run 254 } // end class Player

1 // Fig. 23.6: TicTacToeClient.cs 2 // Client for the TicTacToe program. 3 using System; 4 using System.Drawing; 5 using System.Windows.Forms; 6 using System.Net.Sockets; 7 using System.Threading; 8 using System.IO; 9 10 public partial class TicTacToeClientForm : Form 11 { 12 public TicTacToeClientForm() 13 { 14 InitializeComponent(); 15 } // end constructor 16 17 private Square[ , ] board; // local representation of the game board 18 private Square currentSquare; // the Square that this player chose 19 private Thread outputThread; // Thread for receiving data from server 20 private TcpClient connection; // client to establish connection 21 private NetworkStream stream; // network data stream 22 private BinaryWriter writer; // facilitates writing to the stream 23 private BinaryReader reader; // facilitates reading from the stream 24 private char myMark; // player's mark on the board 25 private bool myTurn; // is it this player's turn? 26 private SolidBrush brush; // brush for drawing X's and O's 27 private bool done = false; // true when game is over 28 29 // initialize variables and thread for connecting to server 30 private void TicTacToeClientForm_Load( object sender, EventArgs e ) 31 { 32 board = new Square[ 3, 3 ]; 33 34 // create 9 Square objects and place them on the board 35 board[ 0, 0 ] = new Square( board0Panel, ' ', 0 ); 36 board[ 0, 1 ] = new Square( board1Panel, ' ', 1 ); 37 board[ 0, 2 ] = new Square( board2Panel, ' ', 2 ); 38 board[ 1, 0 ] = new Square( board3Panel, ' ', 3 ); 39 board[ 1, 1 ] = new Square( board4Panel, ' ', 4 ); 40 board[ 1, 2 ] = new Square( board5Panel, ' ', 5 ); 41 board[ 2, 0 ] = new Square( board6Panel, ' ', 6 ); 42 board[ 2, 1 ] = new Square( board7Panel, ' ', 7 ); 43 board[ 2, 2 ] = new Square( board8Panel, ' ', 8 ); 44 45 // create a SolidBrush for writing on the Squares 46 brush = new SolidBrush( Color.Black ); 47 48 // make connection to server and get the associated 49 // network stream 50 connection = new TcpClient( "127.0.0.1", 50000 ); 51 stream = connection.GetStream(); 52 writer = new BinaryWriter( stream ); 53 reader = new BinaryReader( stream ); 54 55 // start a new thread for sending and receiving messages 56 outputThread = new Thread( new ThreadStart( Run ) ); 57 outputThread.Start(); 58 } // end method TicTacToeClientForm_Load 59 60 // repaint the Squares 61 private void TicTacToeClientForm_Paint( object sender, 62 PaintEventArgs e ) 63 { 64 PaintSquares(); 65 } // end method TicTacToeClientForm_Load 66 67 // game is over 68 private void TicTacToeClientForm_FormClosing( object sender, 69 FormClosingEventArgs e ) 70 { 71 done = true; 72 System.Environment.Exit( System.Environment.ExitCode ); 73 } // end TicTacToeClientForm_FormClosing 74 75 // delegate that allows method DisplayMessage to be called 76 // in the thread that creates and maintains the GUI 77 private delegate void DisplayDelegate( string message ); 78 79 // method DisplayMessage sets displayTextBox's Text property 80 // in a thread-safe manner 81 private void DisplayMessage( string message ) 82 { 83 // if modifying displayTextBox is not thread safe 84 if ( displayTextBox.InvokeRequired ) 85 { 86 // use inherited method Invoke to execute DisplayMessage 87 // via a delegate 88 Invoke( new DisplayDelegate( DisplayMessage ), 89 new object[] { message } ); 90 } // end if 91 else // OK to modify displayTextBox in current thread 92 displayTextBox.Text += message; 93 } // end method DisplayMessage 94 95 // delegate that allows method ChangeIdLabel to be called 96 // in the thread that creates and maintains the GUI 97 private delegate void ChangeIdLabelDelegate( string message ); 98 99 // method ChangeIdLabel sets displayTextBox's Text property 100 // in a thread-safe manner 101 private void ChangeIdLabel( string label ) 102 { 103 // if modifying idLabel is not thread safe 104 if ( idLabel.InvokeRequired ) 105 { 106 // use inherited method Invoke to execute ChangeIdLabel 107 // via a delegate 108 Invoke( new ChangeIdLabelDelegate( ChangeIdLabel ), 109 new object[] { label } ); 110 } // end if 111 else // OK to modify idLabel in current thread 112 idLabel.Text = label; 113 } // end method ChangeIdLabel 114 115 // draws the mark of each square 116 public void PaintSquares() 117 { 118 Graphics g; 119 120 // draw the appropriate mark on each panel 121 for ( int row = 0; row < 3; row++ ) 122 { 123 for ( int column = 0; column < 3; column++ ) 124 { 125 // get the Graphics for each Panel 126 g = board[ row, column ].SquarePanel.CreateGraphics(); 127 128 // draw the appropriate letter on the panel 129 g.DrawString( board[ row, column ].Mark.ToString(), 130 board0Panel.Font, brush, 10, 8 ); 131 } // end for 132 } // end for 133 } // end method PaintSquares 134 135 // send location of the clicked square to server 136 private void square_MouseUp( object sender, 137 System.Windows.Forms.MouseEventArgs e ) 138 { 139 // for each square check if that square was clicked 140 for ( int row = 0; row < 3; row++ ) 141 { 142 for ( int column = 0; column < 3; column++ ) 143 { 144 if ( board[ row, column ].SquarePanel == sender ) 145 { 146 CurrentSquare = board[ row, column ]; 147 148 // send the move to the server 149 SendClickedSquare( board[ row, column ].Location ); 150 } // end if 151 } // end for 152 } // end for 153 } // end method square_MouseUp 154 155 // control thread that allows continuous update of the 156 // TextBox display 157 public void Run() 158 { 159 // first get players's mark (X or O) 160 myMark = reader.ReadChar(); 161 ChangeIdLabel( "You are player "" + myMark + """ ); 162 myTurn = ( myMark == 'X' ? true : false ); 163 164 // process incoming messages 165 try 166 { 167 // receive messages sent to client 168 while ( !done ) 169 ProcessMessage( reader.ReadString() ); 170 } // end try 171 catch ( IOException ) 172 { 173 MessageBox.Show( "Server is down, game over", "Error", 174 MessageBoxButtons.OK, MessageBoxIcon.Error ); 175 } // end catch 176 } // end method Run 177 178 // process messages sent to client 179 public void ProcessMessage( string message ) 180 { 181 // if the move the player sent to the server is valid 182 // update the display, set that square's mark to be 183 // the mark of the current player and repaint the board 184 if ( message == "Valid move." ) 185 { 186 DisplayMessage( "Valid move, please wait. " ); 187 currentSquare.Mark = myMark; 188 PaintSquares(); 189 } // end if 190 else if ( message == "Invalid move, try again." ) 191 { 192 // if the move is invalid, display that and it is now 193 // this player's turn again 194 DisplayMessage( message + " " ); 195 myTurn = true; 196 } // end else if 197 else if ( message == "Opponent moved." ) 198 { 199 // if opponent moved, find location of their move 200 int location = reader.ReadInt32(); 201 202 // set that square to have the opponents mark and 203 // repaint the board 204 board[ location / 3, location % 3 ].Mark = 205 ( myMark == 'X' ? 'O' : 'X' ); 206 PaintSquares(); 207 208 DisplayMessage( "Opponent moved. Your turn. " ); 209 210 // it is now this player's turn 211 myTurn = true; 212 } // end else if 213 else 214 DisplayMessage( message + " " ); // display message 215 } // end method ProcessMessage 216 217 // sends the server the number of the clicked square 218 public void SendClickedSquare( int location ) 219 { 220 // if it is the current player's move right now 221 if ( myTurn ) 222 { 223 // send the location of the move to the server 224 writer.Write( location ); 225 226 // it is now the other player's turn 227 myTurn = false; 228 } // end if 229 } // end method SendClickedSquare 230 231 // write-only property for the current square 232 public Square CurrentSquare 233 { 234 set 235 { 236 currentSquare = value; 237 } // end set 238 } // end property CurrentSquare 239 } // end class TicTacToeClientForm

At the start of the game.

(a)

(b)

After Player X makes the first move.

(c)

(d)

After Player O makes the second move.

(e)

(f)

After Player X makes the final move.

(g)

(h)

The Tie Tac Toe Server's output from the client interactions

(i)

1 // Fig. 23.7: Square.cs 2 // A Square on the TicTacToe board. 3 using System.Windows.Forms; 4 5 // the representation of a square in a tic-tac-toe grid 6 public class Square 7 { 8 private Panel panel; // GUI Panel that represents this Square 9 private char mark; // player's mark on this Square (if any) 10 private int location; // location on the board of this Square 11 12 // constructor 13 public Square( Panel newPanel, char newMark, int newLocation ) 14 { 15 panel = newPanel; 16 mark = newMark; 17 location = newLocation; 18 } // end constructor 19 20 // property SquarePanel; the panel which the square represents 21 public Panel SquarePanel 22 { 23 get 24 { 25 return panel; 26 } // end get 27 } // end property SquarePanel 28 29 // property Mark; the mark on the square 30 public char Mark 31 { 32 get 33 { 34 return mark; 35 } // end get 36 set 37 { 38 mark = value; 39 } // end set 40 } // end property Mark 41 42 // property Location; the square's location on the board 43 public int Location 44 { 45 get 46 { 47 return location; 48 } // end get 49 } // end property Location 50 } // end class Square