// Stop and Wait Protocol
// Sender
import java.io.*;
import java.net.*;
public class Sdr
{
Socket
sender;
ObjectOutputStream
out;
ObjectInputStream in;
String
pkt, ack, data;
int n, i = 0, seq = 0;
Sdr()
{
}
public
void run() throws IOException
{
try
{
BufferedReader br = new BufferedReader(new
InputStreamReader(System.in));
sender
= new Socket("localhost",1500);
seq = 0;
out = new ObjectOutputStream(sender.getOutputStream());
in = new ObjectInputStream(sender.getInputStream());
while(true)
{
System.out.print("\nEnter
the data to send : ");
data = br.readLine().trim();
pkt
= String.valueOf(seq);
pkt
= pkt.concat(data);
out.writeObject(pkt);
out.flush();
if(data.equals("Terminate"))
break;
ack
= (String)in.readObject();
if(ack.equals(String.valueOf(seq)))
{
System.out.println("ack
recerived. ");
seq
= (seq==0)?1:0;
}
else
{
System.out.println("Time
out resending data....\n\n");
}
}
}
catch(Exception
e){}
finally
{
in.close();
out.close();
sender.close();
System.out.println("\nConnection
Terminated.");
}
}
public static void main(String args[]) throws IOException
{
Sdr s = new Sdr();
s.run();
}
}
// Stop and Wait Protocol
// Reciever
import java.io.*;
import java.net.*;
public class Rcr
{
ServerSocket reciever;
Socket conc = null;
ObjectOutputStream
out;
ObjectInputStream in;
String
ack, pkt, data="";
int i = 0, seq = 0;
Rcr()
{
}
public
void run() throws IOException
{
try
{
BufferedReader br = new BufferedReader(new
InputStreamReader(System.in));
reciever
= new ServerSocket(1500,10);
conc
= reciever.accept();
if(conc!=null)
System.out.println("Connection
established :");
out
= new ObjectOutputStream(conc.getOutputStream());
in
= new ObjectInputStream(conc.getInputStream());
while(true)
{
pkt
= (String)in.readObject();
ack
= pkt.substring(0,1);
data
= pkt.substring(1);
if(data.equals("Terminate"))
break;
if(Integer.valueOf(ack)
== seq)
{
System.out.println("\nMsg
received : " + data);
out.writeObject(ack);
seq
= (seq==0)?1:0;
}
else
{
System.out.println("\nMsg : "+
data + "(-> Duplicate data)");
}
}
}
catch(Exception
e)
{
}
finally
{
System.out.println("\nConnection
Terminated.");
in.close();
out.close();
reciever.close();
}
}
public static void main(String args[]) throws IOException
{
Rcr r = new Rcr();
r.run();
}
}
Output:
Sender Window
>javac Sdr.java
>java Sdr
Enter the data to send : asd
ack recerived.
Enter the data to send : qwe
ack recerived.
Enter the data to send : zxc
ack recerived.
Enter the data to send : Terminate
Connection Terminated.
>
Receiver window
>javac Rcr.java
>java Rcr
Connection established :
Msg received : asd
Msg received : qwe
Msg received : zxc
Connection Terminated.
>
