Network operating system in java (NOS)

AIM: Simulating Network Operating System (NOS) commands

Concept: In this Practical make use of socket programming. On the client side design an

application that w ill give the list of commands. The client will invoke these commands.

On the server side these commands will be executed. The implementation of the above

commands will be on the server side.

a) Implementation of stack

Commands: PUSH, POP, DISPLAY, EXIT, etc.

b) Implementation of queue

Commands: INSERT, DELETE, DISPLAY, EXIT, etc.

c) Implementation of link list

Commands: INSERT an element at the beginning, middle and end of the linked

list, DELETE an element from the beginning, middle and end of the linked list.

DISPLAY the linked list. EXIT.

Client program common for all.

Clnt.java

import java.io.*;

import java.net.*;

class clnt

{

public static void main(String args[])

{

try

{

String inc="";

BufferedReader br1=new BufferedReader(new InputStreamReader(System.in));

Socket s=new Socket("localhost",9999);

BufferedReader br2=new BufferedReader(new InputStreamReader(s.getInputStream()));

PrintWriter pw=new PrintWriter(s.getOutputStream(),true);

while(true)

{

System.out.println(br2.readLine());

inc=br1.readLine();

pw.println(inc);

if(inc.equals("D"))

{

s.close();

System.out.println("operation complete...");

break;

}

}

}

catch(Exception e)

{

e.printStackTrace(System.out);

}

}

}

a. Implementation of stack.

Stack1.java

class Stack1

{

private int stack[];

private int tos;

Stack1(int size)

{

stack=new int[size];

tos=-1;

}

boolean isFull()

{

if(tos==stack.length-1)

return true;

else

return false;

}

boolean isEmpty()

{

if(tos<0)

return true;

else

return false;

}

void push(int item)

{

if(!(tos==stack.length-1))

stack[++tos]=item;

}

int pop()

{

return stack[tos--];

}

int[] getStack()

{

return stack;

}

int getCrSize()

{

return (tos+1);

}

}

srvr_stack.java

import java.io.*;

import java.net.*;

Parallel processing & distributed computing M.Sc. IT part-ll 3

class srvr_stack implements Runnable

{

static ServerSocket ss;

Socket s;

BufferedReader br;

PrintWriter pw;

Stack1 stack;

Thread th;

int cid,size=0,sizen=0,i=0,e=0,tmpsize=0;

static int c=0;

String ch=" ";

public srvr_stack(Socket skt) throws Exception

{

this.s=skt;

cid=++c;

System.out.println("client:"+cid+" Accepted-");

br=new BufferedReader(new InputStreamReader(skt.getInputStream()));

pw=new PrintWriter(skt.getOutputStream(),true);

th=new Thread(this);

th.start();

}

public void run()

{

try

{

getSize();

menu();

while(!(ch.equals("D"))){

ch=br.readLine();

if(ch.equals("A")) pushdata();

if(ch.equals("B")) popdata();

if(ch.equals("C")) displaydata();

if(ch.equals("D")) exitstack();

if(ch.equals("M")) menu();

}

}

catch(Exception e)

{

pw.println(e);

}

}

public void pushdata() throws Exception

{

if(stack.isFull()) pw.println("STACK FULL..(press M for menu)");

else

{

for(i=0;i<size;i++)

{

pw.println("ENTER ELEMENT:");

e=Integer.parseInt((br.readLine()).trim());

Parallel processing & distributed computing M.Sc. IT part-ll 4

stack.push(e);

}

size=sizen+size;

pw.println(i+" elements pushed..(press M for menu)");

}

}

public void popdata() throws Exception

{

if(stack.isEmpty()){pw.println("STACK EMPTY..(press M for menu)");}

else pw.println(stack.pop()+" popped.. (press M for menu)");

sizen=stack.getCrSize();

size=tmpsize-sizen;

}

public void displaydata() throws Exception

{

if(stack.isEmpty()){pw.println("STACK EMPTY..(press M for menu)");}

else

{

int[] st=stack.getStack();

String str="";

for(int i=0;i<stack.getCrSize();i++)

str=str+" "+st[i];

pw.println("Stack contains: "+str+" (press M for menu)");

}

}

public void exitstack() throws Exception

{

s.close();

System.out.println("Client "+cid+" exited..");

}

public void menu()

{

pw.println("A.push B.pop C.display D.exit Enter choice:");

}

public void getSize() throws Exception

{

pw.println("enter size of stack:");

size=Integer.parseInt((br.readLine()).trim());

stack=new Stack1(size);

tmpsize=size;

}

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

{

ss=new ServerSocket(9999);

System.out.println("server started...");

while(true)

{

Socket sckt=ss.accept();

srvr_stack server=new srvr_stack(sckt);

}}}