Socket Communication Sockets provide an abstraction of two-point communication The two sides only read/write without concern for how data is translated (encoded) and transmitted Socket is a pair (address, port) address: www.google.com, turing.cc.gettysburg.edu, 135.24.78.123 port: 21 (ftp), 22 (ssh), 23 (telnet), 80 (http), 101 (pop mail)

Socket Communication web server listen on port 80 server (turing.cc.gettysburg.edu) client (135.24.78.123) web server listen on port 80

Socket Communication web server listen on port 80 server (turing.cc.gettysburg.edu) request web page turing.cc…:80 client (135.24.78.123) socket 135.24.78.123:1234 web server listen on port 80

Socket Communication web server listen on port 80 server (turing.cc.gettysburg.edu) request web page turing.cc…:80 client (135.24.78.123) socket 135.24.78.123:1234 accept request socket tuing.cc…..:5789 web server listen on port 80

Socket Communication web server listen on port 80 server (turing.cc.gettysburg.edu) client (135.24.78.123) socket tuing.cc…..:5789 socket 135.24.78.123:1234 web server listen on port 80

Socket Communication web server listen on port 80 server (turing.cc.gettysburg.edu) client (135.24.78.123) socket tuing.cc…..:5789 socket 135.24.78.123:1234 request web page turing.cc…:80 client (135.24.78.567) web server listen on port 80 socket 135.24.78.567:1024

Socket Communication web server listen on port 80 server (turing.cc.gettysburg.edu) client (135.24.78.123) socket tuing.cc…..:5789 socket 135.24.78.123:1234 request web page turing.cc…:80 client (135.24.78.567) web server listen on port 80 socket 135.24.78.567:1024 accept request socket tuing.cc…..:8019

Socket Communication web server listen on port 80 server (turing.cc.gettysburg.edu) client (135.24.78.123) socket tuing.cc…..:5789 socket 135.24.78.123:1234 client (135.24.78.567) web server listen on port 80 socket tuing.cc…..:8019 socket 135.24.78.567:1024

Multi-Threaded Server client (135.24.78.123) request web page turing.cc…:80 server socket (addr : port) turing.cc.gettysburg.edu : 80 socket (addr : port) 135.24.78.123 : 1234 socket tuing.cc…..:5789 request web page turing.cc…:80 client (128.4.99.100) socket (addr : port) 128.4.99.100 : 1234 socket tuing.cc…..:8019 listening thread (wait for connect)

Simple Server (one client) Open the Server Socket ServerSocket server = new ServerSocket(5678); Wait for Client Request Socket connection = server.accept(); Create Streams for Communication OutputStream os = connection.getOutputStream(); DataOutputStream output = new DataOutputStream (os); Carry Out Communication output.writeUTF("Hi there"); Close Communication output.close(); os.close(); connection.close(); server.close();

Simple Server (one client) public static void main(String[] args) { // Register service on port 1234 ServerSocket server = new ServerSocket(1234); // Wait and accept a connection Socket connection = server.accept(); // Get a communication stream associated with the socket OutputStream os = connection.getOutputStream(); DataOutputStream output = new DataOutputStream(os); // Send a string! output.writeUTF("Hi there"); // Close the connection output.close(); os.close(); connection.close(); server.close(); }

Multi-Threaded Server Open the Server Socket ServerSocket server = new ServerSocket(5678); Wait for Client Request Socket connection = server.accept(); Spawn a client thread (give the connection) Create Streams for Communication OutputStream os = connection.getOutputStream(); DataOutputStream output = new DataOutputStream (os); Carry Out Communication output.writeUTF("Hi there"); Close Communication output.close(); os.close(); connection.close(); server.close();

Simple Server (one client) public static void main(String[] args) { // Register service on port 1234 ServerSocket server = new ServerSocket(1234); // Wait and accept a connection while (true) { Socket connection = server.accept(); Thread client = new ClientThread(connection); } Code for ClientThread: // get communication channel associated with the socket OutputStream os = connection.getOutputStream(); DataOutputStream output = new DataOutputStream (os); output.writeUTF("Hi there"); // communicate os.close(); output.close(); // close resources connection.close();

Simple Client MIDlet (no change) Create a Socket Connection SocketConnection connection = (SocketConnection)Connector.open("socket://gbcs10:5678"); Create Streams for Communication InputStream is = connection.openInputStream(); DataInputStream input = new DataInputStream(is); Carry Out Communication String data = new String (input.readUTF()); Close Communication is.close(); input.close(); connection.close();

Simple Client MIDlet (no change) try { SocketConnection connection = (SocketConnection) Connector.open("socket://gbcs10:1234"); InputStream is = connection.openInputStream(); DataInputStream input = new DataInputStream(is); String data = new String (input.readUTF()); is.close(); input.close(); connection.close(); } catch (. . .) {

Synchronous Multi-Threaded Chat Server Lab Exercise Synchronous Multi-Threaded Chat Server