public static void main(string[] args) throws IOException { sock = new Socket(args[0], Integer.parseInt(args[1]));

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1 Echo Client&Server Application EchoClient import java.net.*; import java.io.*; class EchoClient public static void main(string[] args) throws IOException if (args.length < 2) number>"); System.err.println("Usage: java EchoClient <IP address> <Port System.exit(0); BufferedReader in = null; PrintWriter out = null; BufferedReader fromuser = null; Socket sock = null; try sock = new Socket(args[0], Integer.parseInt(args[1])); // set up the necessary communication channels in = new BufferedReader(new InputStreamReader(sock.getInputStream())); fromuser = new BufferedReader(new InputStreamReader(System.in)); out = new PrintWriter(sock.getOutputStream(),true);

2 while (true) String line = fromuser.readline(); if (line == null line.equals("bye")) out.println("bye"); break; out.println(line); System.out.println(in.readLine()); catch (IOException ioe) System.err.println(ioe); finally if (in!= null) in.close(); if (fromuser!= null) fromuser.close(); if (out!= null) out.close(); if (sock!= null) sock.close();

3 EchoServer: import java.net.*; import java.io.*; public class EchoServer public static void main(string[] args) throws IOException if (args.length < 1) Number> "); System.err.println("Usage: java EchoServer <Port System.exit(0); ServerSocket sock = null; try // establish the socket sock = new ServerSocket(Integer.parseInt(args[0])); /** * listen for new connection requests. * when a request arrives, service it * and resume listening for more requests.

4 */ while (true) // now listen for connections Socket client = sock.accept(); // service the connection ServiceConnection(client); catch (IOException ioe) System.err.println(ioe); finally if (sock!= null) sock.close(); public static void ServiceConnection(Socket client) BufferedReader networkbin = null; OutputStreamWriter networkpout = null; try /**

5 socket. * get the input and output streams associated with the */ networkbin = new BufferedReader(new InputStreamReader(client.getInputStream())); networkpout = new OutputStreamWriter(client.getOutputStream()); /** returns "bye\r\n" * the following successively reads from the input stream and * what was read. The loop terminates with ^D or the string * from the input stream. */ while (true) String line = networkbin.readline(); if ( (line == null) line.equals("bye")) break; networkpout.write("server [ "+line+" ]\r\n"); networkpout.flush(); catch (IOException ioe) System.err.println(ioe);

6 finally try if (networkbin!= null) networkbin.close(); if (networkpout!= null) networkpout.close(); if (client!= null) client.close(); catch (IOException ioee) System.err.println(ioee); // end try // end ServiceConnection 1. Program Execution Echo Client Server Compilation javac EchoServer.java javac EchoClient.java Execution java EchoServer portno(123)

7 java EchoClient ipaddrofserver(localhost) portno(123) the character must typed by the client must reflect back at the client...until the client quits by typing 'bye' REMOTE COMMAND EXECUTION RceClient import java.net.*; import java.io.*; class RceClient public static void main(string args[]) try DatagramSocket ds=new DatagramSocket(2000); InetAddress ia=inetaddress.getbyname(" "); byte[] msg=new byte[255]; DataInputStream dis = new DataInputStream(System.in); String ss = dis.readline(); msg = ss.getbytes(); DatagramPacket dp = new DatagramPacket(msg,msg.length,ia,1000); ds.send(dp);

8 catch(exception e) RceServer import java.io.*; import java.net.*; class RceServer public static void main(string args[]) try DatagramSocket ds = new DatagramSocket(1000); byte[] msg = new byte[255]; DatagramPacket dp = new DatagramPacket(msg,msg.length); ds.receive(dp); String ss = new String(msg); System.out.println("The Path is:" + ss); Runtime rt = Runtime.getRuntime();

9 Process p = null; p = rt.exec(ss); catch(exception e) Program Execution Compilation javac RceServer.java javac RceClient.java Execution java RceServer java RceClient mspaint.exe Chat Application //Client Application import java.net.*; import java.io.*; public class Client implements Runnable Socket s;

10 BufferedReader br; BufferedWriter bw; BufferedReader ppp; String input = null; public static void main(string arg[]) new Client(); public void run() try s.setsotimeout(1); catch(exception e) while (true) try System.out.println("Server: "+br.readline()); catch (Exception h) public Client()

11 try s = new Socket(" ",100); br = new BufferedReader(new InputStreamReader(s.getInputStream())); bw = new BufferedWriter(new OutputStreamWriter(s.getOutputStream())); ppp = new BufferedReader(new InputStreamReader(System.in)); Thread th; th = new Thread(this); th.start(); bw.write("hello"); bw.newline(); bw.flush(); while(true) input = ppp.readline(); bw.write(input); bw.newline(); bw.flush();

12 catch(exception e) //Server Application import java.net.*; import java.io.*; public class ServerApp implements Runnable ServerSocket s; Socket s1; BufferedReader br; BufferedWriter bw; BufferedReader ppp; String input = null; public void run() try s1.setsotimeout(1); catch(exception e)

13 while (true) try System.out.println("Client: "+br.readline()); catch (Exception h) public static void main(string arg[]) new ServerApp(); public ServerApp() try s = new ServerSocket(100); s1=s.accept(); br = new BufferedReader(new InputStreamReader(s1.getInputStream())); bw = new BufferedWriter(new OutputStreamWriter(s1.getOutputStream())); ppp = new BufferedReader(new InputStreamReader(System.in));

14 Thread th; th = new Thread(this); th.start(); while(true) input = ppp.readline(); bw.write(input); bw.newline(); bw.flush(); catch(exception e) Program Execution Chat Application Compilation javac ServerApp.java javac Client.java Execution Z:\NetworkLab\Chat>java ServerApp Client: Hello Client: hjsdfsdf

15 dsflkfl Z:\NetworkLab\Chat>java Client hjsdfsdf Server: dsflkfl Sdffsa REMOTE COMMAND EXECUTION RceClient import java.net.*; import java.io.*; class RceClient public static void main(string args[]) try DatagramSocket ds=new DatagramSocket(2000); InetAddress ia=inetaddress.getbyname(" "); byte[] msg=new byte[255]; DataInputStream dis = new DataInputStream(System.in); String ss = dis.readline(); msg = ss.getbytes();

16 DatagramPacket dp = new DatagramPacket(msg,msg.length,ia,1000); ds.send(dp); catch(exception e) RceServer import java.io.*; import java.net.*; class RceServer public static void main(string args[]) try DatagramSocket ds = new DatagramSocket(1000); byte[] msg = new byte[255]; DatagramPacket dp = new DatagramPacket(msg,msg.length); ds.receive(dp); String ss = new String(msg);

17 System.out.println("The Path is:" + ss); Runtime rt = Runtime.getRuntime(); Process p = null; p = rt.exec(ss); catch(exception e) Program Execution Compilation javac RceServer.java javac RceClient.java Execution java RceServer java RceClient mspaint.exe

CS2307 NETWORKS LAB 1. Programs using TCP Sockets (like date and time server & client, echo server & client, etc.) 2. Programs using UDP Sockets

CS2307 NETWORKS LAB 1. Programs using TCP Sockets (like date and time server & client, echo server & client, etc.) 2. Programs using UDP Sockets (like simple DNS) 3. Programs using Raw sockets (like packet