Modify, compile, and test the client program in Table 25.13 and the server program in Table 25.12 to do the following: The client program needs to read the request string from a file and store the response string in another file. The name of the file needs to be passed as the argument to the main method of the client program. The server program needs to accept the request string, change all lowercase letters to uppercase letters, and return the result.

Table 25.12

Table 25.13

Table 25.12 A simple UDP server program 1 import java.net.*; 2 import java.io."; 4 public class UDPServer final int buffSize = .: I/ Add buffer size. DatagramSocket sock; String request; String response; InetAddress clientAddr; 8 9 10 11 int clientPort; 12 13 UDPServer (DatagramSocket s) 14 15 sock = s; 16 17 18 void getRequest ) 19 { 20 try 21 { byte [] recvBuff = new byte [buffSize]: DatagramPacket recvPacket = new DatagramPacket (recvBuff, buffSize); sock.receive (recvPacket); recvBuff = recvPacket.getData (); request = new String (recvBuff, 0, recvBuff.length); clientAddr = recvPacket.getAddress (); clientPort = recvPacket.getPort (); 28 catch (SocketException ex) 31 32 System.err.println ("SocketException in getRequest"); 33 } 34 catch (IOException ex) 35 36 System.err.println ("IOException in getRequest"); 37 } 38 39 40 void process () 41 { 42 // Add code for processing the request and creating the response. 43 45 void sendResponse) 46 47 try 49 byte [] sendBuff = new byte [buffSize]; sendBuff = response.getBytes (); 51 DatagramPacket sandpaper = new DatagramPacket (sendBuff, sendBuff.length, clntAddr, clientPort); sock.send(sendPacket); } 55 catch (SocketException ex) System.err.println ("SocketException in sendResponse"); 58 59 catch (IOException ex) 60 61 System.err.printin ("IOException in sendResponse"); 62 63 64 65 public static void main (String [] args) throws IOException, SocketException 66 67 final int port =...; // Add server port number. 68 DatagramSocket sock = new DatagramSocket (port); 69 while (true) 70 { 71 UDPServer server = new UDPServer (sock); 72 server.getRequest (); 73 server.process (); 74 server.sendResponse (); 75 76 } // End of main 77 )// End of UDPServer class