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‎README.md

Whitespace-only changes.

‎SelectiveRepeatReceiver.java

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/*
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* To change this license header, choose License Headers in Project Properties.
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* To change this template file, choose Tools | Templates
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* and open the template in the editor.
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*/
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package selectiverepeatreceiver;
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import java.io.BufferedReader;
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import java.io.IOException;
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import java.io.InputStreamReader;
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import java.io.PrintWriter;
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import static java.lang.Thread.sleep;
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import java.net.Socket;
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import java.util.Arrays;
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import java.util.Scanner;
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/**
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*
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* @author Danyal
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*/
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public class SelectiveRepeatReceiver {
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public static void main(String[] args) throws InterruptedException
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{
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Scanner scan = new Scanner(System.in);
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try
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{
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System.out.println("Enter the IP Address: ");
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String IP = scan.next();
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System.out.println("Enter port number: ");
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String port = scan.next();
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Socket usocket = new Socket(IP, Integer.parseInt(port));
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BufferedReader inbuffer = new BufferedReader(new InputStreamReader(usocket.getInputStream()));
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PrintWriter outbuffer = new PrintWriter(usocket.getOutputStream(), true);
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int rn = 0;
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boolean naksent = false, ackneeded = false;
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boolean datareceived = false;
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int m = Integer.parseInt(inbuffer.readLine());
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boolean[] marked = new boolean[m];
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String data[] = new String[m];
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for(int i = 0; i < marked.length; i++)
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{
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marked[i] = false;
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}
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while(!datareceived)
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{
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outbuffer.println("FRAME");
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sleep(300);
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int frame = Integer.parseInt(inbuffer.readLine());
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if(frame != rn && !naksent && frame > rn)
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{
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outbuffer.println("NACK" + rn);
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System.out.println("Received frame number" + frame + " when " + rn + " was expected. Sending NACK" + rn + ".");
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System.out.println("Sent NACK" + rn);
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naksent = true;
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continue;
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}
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else if(frame < rn)
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{
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System.out.println("Discarded frame number " + frame + " as it's < rn");
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continue;
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}
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if(isBetween(frame, rn, rn + m, m)&&(!marked[frame]))
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{
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System.out.println("Stored " + frame + " at " + frame + ".");
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data[frame] = "Frame" + Integer.toString(frame);
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marked[frame] = true;
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System.out.println("Marked " + frame + " as received.");
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while(marked[rn])
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{
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System.out.println(rn + " is marked. Moving to " + (rn + 1) + ".");
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rn++;
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ackneeded = true;
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if(rn >= marked.length)
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{
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datareceived = true;
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break;
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}
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}
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if(ackneeded)
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{
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System.out.println("ACK is needed. Sending out ACK" + rn + ".");
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outbuffer.println("ACK"+rn);
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ackneeded = false;
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naksent = false;
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}
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}
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System.out.println(Arrays.toString(data));
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}
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System.out.println("Data successfully retreieved. Final output is:\n" + Arrays.toString(data));
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outbuffer.println("FINISH");
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inbuffer.close();
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outbuffer.close();
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usocket.close();
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}
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catch(IOException e)
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{
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e.printStackTrace();
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}
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}
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static boolean isBetween(int num, int n1, int n2, int mod)
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{
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if(num == n1)
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return true;
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while(n1 != n2)
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{
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n1 = (n1 + 1)%mod;
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if(num == n1)
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return true;
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}
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return false;
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}
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}

‎SelectiveRepeatSender.java

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/*
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* To change this license header, choose License Headers in Project Properties.
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* To change this template file, choose Tools | Templates
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* and open the template in the editor.
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*/
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package selectiverepeatsender;
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import java.io.BufferedReader;
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import java.io.IOException;
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import java.io.InputStreamReader;
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import java.io.PrintWriter;
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import java.net.ServerSocket;
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import java.net.Socket;
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import java.util.Scanner;
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/**
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*
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* @author Danyal
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*/
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public class SelectiveRepeatSender
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{
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public static void main(String[] args) throws InterruptedException
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{
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Scanner scan = new Scanner(System.in);
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int sw, sf = 0, sn = 0, m;
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System.out.println("Input the value of 'm': ");
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m = scan.nextInt();
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sw = (int)Math.pow(2, m - 1);
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int timeout = 200;
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String[] data = new String[(int)Math.pow(2,m)];
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Timeout[] timers = new Timeout[sw];
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for(int i = 0; i < data.length; i++)
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{
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data[i] = Integer.toString(i);
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} //Generating string data to send.
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m = (int)Math.pow(2, m);
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try
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{
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int portnumber = 2325;
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ServerSocket uservice = new ServerSocket(portnumber);
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System.out.println("Port number is: " + portnumber);
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Socket usocket = uservice.accept();
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System.out.println("accepted");
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BufferedReader inbuffer = new BufferedReader(new InputStreamReader(usocket.getInputStream()));
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PrintWriter outbuffer = new PrintWriter(usocket.getOutputStream(), true);
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long[] timervals = new long[sw];
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for(int i = 0; i < timervals.length; i++)
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timervals[i] = Long.MAX_VALUE;
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outbuffer.println(Integer.toString(m));
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System.out.println("Done writing.");
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while(true)//for(int i = 0; i < data.length; i++)
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{
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String incoming = inbuffer.readLine();
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if(incoming.contains("ACK"))
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{
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if(incoming.contains("NACK"))
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{
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System.out.println(incoming + " received.");
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int nackno = Integer.parseInt(incoming.substring(4, incoming.length()));
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if(isBetween(nackno, Integer.parseInt(data[sf%m]), Integer.parseInt(data[sn%m]), m))
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{
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System.out.println("Sending out " + data[nackno] + ".");
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outbuffer.println(data[nackno]);
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if(timers[nackno%sw]!=null)
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{
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System.out.println("Cancelling timer number " + nackno + ".");
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timers[nackno%sw].timer.cancel();
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timers[nackno%sw] = null;
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}
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System.out.println("Creating new timer in " + nackno);
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timers[nackno%sw] = new Timeout(outbuffer, data[nackno], timeout);
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}
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}
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else
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{
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System.out.println(incoming + " received.");
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int ackno = Integer.parseInt(incoming.substring(3, incoming.length()));
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if(isBetween(ackno, Integer.parseInt(data[sf%m]), Integer.parseInt(data[sn%m]), m))
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{
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while(Integer.parseInt(data[sf%m]) != ackno)
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{
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System.out.println("Cancelling timer number " + sf%sw + ".");
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timers[sf%sw].timer.cancel();
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timers[sf%sw] = null;
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sf++;
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}
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}
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}
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}
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else if(incoming.contains("FRAME"))
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{
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System.out.println("Receieved frame request packet.");
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if(sn-sf >= sw)
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{
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System.out.println("Window size is already max. Not sending out frame.");
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continue;
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}
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System.out.println("Sending out frame number " + sn%m);
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outbuffer.println(data[sn%m]);
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timers[sn%sw] = new Timeout(outbuffer, data[sn%m], timeout);
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sn++;
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}
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else if(incoming.equals("FINISH"))
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{
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System.out.println("Finished serving the client.");
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break;
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}
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//sleep(50);
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}
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inbuffer.close();
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outbuffer.close();
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usocket.close();
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uservice.close();
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System.exit(0);
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}
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catch (IOException e)
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{
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System.out.println(e);
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}
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}
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static boolean isBetween(int num, int n1, int n2, int mod)
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{
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if(num == n1)
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return true;
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while(n1 != n2)
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{
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n1 = (n1 + 1)%mod;
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if(num == n1)
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return true;
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}
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return false;
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}
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}

‎Timeout.java

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/*
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* To change this license header, choose License Headers in Project Properties.
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* To change this template file, choose Tools | Templates
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* and open the template in the editor.
5+
*/
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package selectiverepeatsender;
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import java.io.PrintWriter;
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import java.util.Timer;
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import java.util.TimerTask;
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/**
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*
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* @author Danyal
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*/
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public class Timeout
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{
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Timer timer;
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PrintWriter stream;
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String data;
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public Timeout(PrintWriter stream, String data, int milliseconds)
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{
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this.stream = stream;
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timer = new Timer();
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timer.scheduleAtFixedRate(new TimeoutTask(), milliseconds, milliseconds);
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this.data = data;
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System.out.println("Created new timer with data " + data + ".");
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}
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class TimeoutTask extends TimerTask
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{
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@Override
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public void run()
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{
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System.out.println("Timed out, resending " + data + ".");
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stream.println(data);
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}
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}
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}

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