Question

Running a program in Java about slidsender and slidreceiver with a brief explanation what each one is doing.

slidreceiver

import java.net.*; import java.io.*; class slidreceiver

{

public static void main(String a[])throws Exception

{

Socket s=new Socket(InetAddress.getLocalHost(),10); DataInputStream in=new

DataInputStream(s.getInputStream()); PrintStream p=new

PrintStream(s.getOutputStream());

int i=0,rptr=-1,nf,rws=8; String rbuf[]=new String[8]; String ch;

System.out.println(); do

{

nf=Integer.parseInt(in.readLine()); if(nf<=rws-1)

{

for(i=1;i<=nf;i++)

{

rptr=++rptr%8; rbuf[rptr]=in.readLine();

System.out.println("The received Frame " +rptr+" is : "+rbuf[rptr]);

}

rws-=nf; System.out.println("\nAcknowledgment sent\n"); p.println(rptr+1);

rws+=nf; }

else break;

ch=in.readLine();

}

while(ch.equals("yes"));

}

}

slidsender

import java.net.*;

import java.io.*;

import java.rmi.*;

public class slidsender

{

public static void main(String a[]) throws Exception

{

ServerSocket ser=new ServerSocket(1024);

Socket s=ser.accept();

DataInputStream in=new DataInputStream(System.in);

DataInputStream in1=new DataInputStream(s.getInputStream());

String sbuff[]=new String[8];

PrintStream p;

int sptr=0,sws=8,nf,ano,i;

String ch;

do

{

p=new PrintStream(s.getOutputStream());

System.out.print("Enter the no. of frames : ");

nf=Integer.parseInt(in.readLine());

p.println(nf);

if(nf<=sws-1) {

System.out.println("Enter "+nf+" Messages to be send\n");

for(i=1;i<=nf;i++) {

sbuff[sptr]=in.readLine();

p.println(sbuff[sptr]);

sptr=++sptr%8;} sws-=nf;

System.out.print("Acknowledgment received");

ano=Integer.parseInt(in1.readLine());

System.out.println(" for "+ano+" frames"); sws+=nf;

} else

{

System.out.println("The no. of frames exceeds window size");

break;

}

System.out.print("\nDo you wants to send some more frames : ");

ch=in.readLine();

p.println(ch);

}

while(ch.equals("yes"));

s.close();

}

}

Answer 1

The above program is written to explain the messaging technique over computer network. Here the two classes 'slidsender' and 'slidreceiver' are the two nodes of communication.

Slidsender:

The slidsender is the node who is initiating the communication by sending a predefined window of bytes of information to the receiver. The window size is already defined and if the message increases the window size then it throws the error that the frames exxeed the window size. Also it has a process of receiving acknowledgment from the other node to ensure the message has been received properly by the receiver node. After one complete delivery, the program asks the sender if he wants to send more frames of information. Depending upon the choice the program continues or aborts.

Slidreceiver:

The slidreceiver is the node who is on the other side of the network, receiving message from the slidsender. After the connection is established between the two nodes, the frames containing sensitive information starts to pass through the network. The slidreceiver, being on the other end receives the message. Once one window frame is completely received, the slidreceiver sends an acknowledgement byte to let the slidsender know that the frame has been properly received.

Due to network congestion or traffic, it may sometime happen that the frames containing sensitive information may not get sent completely and some bytes get missing. Therefore, the acknowledgment byte plays a very important role to let both the parties know that the communication was successful and the data has reached from one side to another safely.