hello guys.

1. C Code For Go Back N Arq

Oct 29, 2012 - 14 min - Uploaded by DoggysamaThis was to simulate the Go Back N protocol for TCP. Emil ruder typography a manual of design pdf.

so far i've managed to build a skeleton..now it seems i'm badly in need of some flesh.
overview:
I've written separate sender and reciever portions..the sender portion goes like this:

C Code For Go Back N Arq

import java.io.*;
import java.net.*;
public class SendGBN{
//constants
public static byte N = 10; //the N from 'Go-Back-N'
public static byte MAX_SEQ_NUMBER = 20; //The maximum sequence number
public static int PORT = 7609; //the receiver's port
public static int DELAY = 1000; //1 second delay for timeout
//the socket
DatagramSocket socket;
//the ip address of the receiver
InetAddress ipAddress;
//variables from the algorithm
byte base = 1;
byte nextSeqNum = 1;
//needed for receiver thread
volatile boolean done = false;
//number of packets sent, but unacknowledged
int unAckedPackets = 0;
//////////////////////////////
//
// other instance variables
//
//main program
//hostname can be included on the command line
//if not, assume the receiver is listening on this machine
public static void main(String[] args) throws IOException{
InetAddress ipAddress = null;
if(args.length > 0){
//get specified host
ipAddress = InetAddress.getByName(args[0]);
}
else{
//use default local host
ipAddress = InetAddress.getByName('localhost'); //loopback
}
//create a new sender
SendGBN sender = new SendGBN(ipAddress);
//start processing the user's data
sender.processUserData();
}
//constructor
public SendGBN(InetAddress ip) throws IOException{
ipAddress = ip;
socket = new DatagramSocket();
//create receiver thread
ACKListener rcv = new ACKListener();
//start the thread
rcv.start();
/////////////////////////////
//
// other initialization
//
}
//deals with getting the data from the user to send
public void processUserData() throws IOException{
//create input reading mechanism
BufferedReader in =
new BufferedReader(new InputStreamReader(System.in));
System.out.println('Enter some text, to end place a . on a line alone.');
String line = null;
while((line = in.readLine()) != null && !(line.equals('.'))){
//send one packet per character
for(int i = 0; i < line.length(); i++){
char c = line.charAt(i);
//wait until the queue is no longer full
while(unAckedPackets N){
//we can do this because we will be running other threads
//we'll give them a chance to run
Thread.yield();
}
sendPacket©;
}
///////////////////////////////////////////
//
// wait until the queue is no longer full
// send an end of line character
//
}
done = true;
socket.close();
System.out.println('Done!');
}
/*
* The following three methods
* are defined as synchronized so that only one can be active
* at a time from any given thread (main thread, ackListener or timer.
*
*/
public synchronized void sendPacket(char c) throws IOException{
///////////////////////////////////////////
//
// Turn the char c into a packet and send it off.(how!?)
//
// Called from processUserData().
//
//
//
}
public synchronized void receivePacket(DatagramPacket ack){
///////////////////////////////////////////
//
// Process a received packet(how!?)
// Called from the ACKListener thread
//
//
//
}
public synchronized void timeOut(){
///////////////////////////////////////////
//
// Process a message from the timer. (how?)
// Called from the timer.
//
//
//
}
class ACKListener extends Thread{
public void run(){
try{
while(!done){
//listen for packet
DatagramPacket ack = null;
///////////////////////////////////////////
//
// Get an incoming ACK packet
//
//process it
receivePacket(ack);
}
}
catch(IOException ioe){
//Will enter here if the thread is listening for a packet
//when we quit, and that's ok.
}
}
}
}
where I need help is mainly the sendPacket(),recievepacket() and timeOut() methods..
can anybody correct and complete the code?..it would be a great help !.=)