Problem 2
State whether each of the following is true or false. If false, explain why. a) UDP is a connection-oriented protocol. b) With stream sockets a process establishes a connection to another process. c) A server waits at a port for connections from a client. d) Datagram packet transmission over a network is reliable - packets are guaranteed to arrive in sequence. e) For security reasons, many web browsers, such as Mozilla, allow Java applets to do file processing only on the machines on which they execute. f) Web browsers often restrict an applet so that it can communicate only with the machine from which it was originally downloaded.
Problem 3
Distinguish between connection-oriented and connectionless network services.
Problem 5
Under what circumstances would a SocketException be thrown?
Problem 21
(Modifications to the Multithreaded Tic-Tac-Toe Program) The programs in Figs. 24.13 and 24.15 implemented a multithreaded, client/server version of the game of Tic- Tac-Toe. Our goal in developing this game was to demonstrate a multithreaded server that could process multiple connections from clients at the same time. The server in the example is really a mediator between the two client applets - it makes sure that each move is valid and that each client moves in the proper order. The server does not determine who won or lost or whether there was a draw. Also, there is no capability to allow a new game to be played or to terminate an existing game. The following is a list of suggested modifications to Figs. 24.13 and 24.15: a) Modify the TicTacToeServer class to test for a win, loss or draw on each move in the game. Send a message to each client applet that indicates the result of the game when the game is over. b) Modify the TictactoeC 7 ient class to display a button that when clicked allows the client to play another game. The button should be enabled only when a game completes. Note that both class TictactoeC 7 ient and class TictactoeServer must be modified to reset the board and all state information. Also, the other TicTacToeClient should be notified that a new game is about to begin so that its board and state can be reset. c) Modify the TictactoeCl ient class to provide a button that allows a client to terminate the program at any time. When the user clicks the button, the server and the other client should be notified. The server should then wait for a connection from another client so that a new game can begin. d) Modify the TictactoeCl ient class and the TicTacToeServer class so that the winner of a game can choose game piece \(\mathrm{X}\) or \(\mathrm{O}\) for the next game. Remember: \(\mathrm{X}\) always goes first. e) If you would like to be ambitious, allow a client to play against the server while the server waits for a connection from another client.
