Remote Method Invocation (RMI) supporting the Distributed Computing in Java.

Remote Method Invocation (RMI) supporting the Distributed Computing in Java.

Create a Client and Server application where the client invokes methods via an interface. These methods are implemented on the server side.

A) Design a GUI based Calculator (Standard/Scientific)

B) Retrieve Time and Date from Server to Client

C) Equation Solver
Equation: (a-b)2=a2-2ab+b2

(A) Design a GUI based Calculator (Standard/Scientific)
Code:

ICalc.java

import java.rmi.*;

public interface ICalc   
 extends java.rmi.Remote
    {
  public float calculate(float num1,float num2,String op)
    throws java.rmi.RemoteException;
    }

ICalcImpl.java

import java.rmi.*;
import java.math.*;

public class ICalcImpl
  extends java.rmi.server.UnicastRemoteObject
   implements ICalc
    {

public ICalcImpl() throws java.rmi.RemoteException{}

public float calculate(float num1,float num2,String op) throws java.rmi.RemoteException
    {
   
   if(op.equals("+"))
    {
    return num1+num2;
    }


   if(op.equals("-"))
    {
    return num1-num2;
    }
   if(op.equals("*"))
    {
    return num1*num2;
    }


    if(op.equals("/"))
    {
    return num1/num2;
    }
   if(op.equals("1/x"))
    {
    return 1/num1;
    }

   if(op.equals("s"))
    {
    return (float)(Math.sqrt(num1));
    }

  else
       return 0;
   
        }
    }

ICalcServer.java

import java.rmi.*;

public class ICalcServer
{
public ICalcServer()
{
      System.out.println("Server created");

     try
{
      ICalc dt = new ICalcImpl();
        Naming.rebind("abc",dt);
}
catch(Exception e){
    System.out.println("Trouble:"+e);
}
}
public static void main(String args[])
{
new ICalcServer();
}
}

ICalcClient.java

import java.rmi.*;
import java.net.MalformedURLException;
import java.awt.*;
import javax.swing.*;
import java.awt.event.*;

public class ICalcClient extends JFrame implements ActionListener
{
ICalc dt;

JTextField txtScr;
JButton cmdBack, cmdClr, cmdEnter, cmdSign, cmdPlus, cmdMinus,
cmdMult, cmdDiv, cmdSqrt,cmdRecipro,cmdDot;
JButton cmdOne, cmdTwo, cmdThree, cmdFour, cmdFive, cmdSix,
cmdSeven, cmdEight,cmdNine,cmdZero;
Float num1,num2,ans;
String op;

char ch;
int asc;
Container cp;
ICalcClient()
{
cp=getContentPane();
cp.setLayout(null);

try
{
dt=(ICalc) Naming.lookup("abc");
}

catch(Exception e)
{}

txtScr=new JTextField();
txtScr.setBounds(10,10,200,30);
//txtScr.addKeyListener(this);
cp.add(txtScr);
cmdBack= new JButton("<<");
cmdBack.setBounds(10,50,50,40);
cp.add(cmdBack);
cmdBack.addActionListener(this);
cmdClr=new JButton("C");
cmdClr.setBounds(70,50,50,40);
cp.add(cmdClr);
cmdClr.addActionListener(this);


cmdSeven=new JButton("7");
cmdSeven.setBounds(10,100,50,40);
cp.add(cmdSeven);
cmdSeven.addActionListener(this);
cmdEight=new JButton("8");
cmdEight.setBounds(70,100,50,40);
cp.add(cmdEight);
cmdEight.addActionListener(this);
cmdNine=new JButton("9");
cmdNine.setBounds(130,100,50,40);
cp.add(cmdNine);
cmdNine.addActionListener(this);
cmdDiv=new JButton("/");
cmdDiv.setBounds(190,100,50,40);
cp.add(cmdDiv);
cmdDiv.addActionListener(this);
cmdSqrt=new JButton("s");
cmdSqrt.setBounds(250,100,50,40);
cp.add(cmdSqrt);
cmdSqrt.addActionListener(this);
cmdFour=new JButton("4");
cmdFour.setBounds(10,150,50,40);
cp.add(cmdFour);
cmdFour.addActionListener(this);
cmdFive=new JButton("5");
cmdFive.setBounds(70,150,50,40);
cp.add(cmdFive);
cmdFive.addActionListener(this);
cmdSix=new JButton("6");
cmdSix.setBounds(130,150,50,40);
cp.add(cmdSix);
cmdSix.addActionListener(this);
cmdMult=new JButton("*");
cmdMult.setBounds(190,150,50,40);
cp.add(cmdMult);
cmdMult.addActionListener(this);
cmdOne=new JButton("1");

cmdOne.setBounds(10,200,50,40);
cp.add(cmdOne);
cmdOne.addActionListener(this);
cmdTwo=new JButton("2");
cmdTwo.setBounds(70,200,50,40);
cp.add(cmdTwo);
cmdTwo.addActionListener(this);
cmdThree=new JButton("3");
cmdThree.setBounds(130,200,50,40);
cp.add(cmdThree);
cmdThree.addActionListener(this);
cmdMinus=new JButton("-");
cmdMinus.setBounds(190,200,50,40);
cp.add(cmdMinus);
cmdMinus.addActionListener(this);
cmdRecipro=new JButton("1/x");
cmdRecipro.setBounds(250,200,60,40);
cp.add(cmdRecipro);
cmdRecipro.addActionListener(this);
cmdZero=new JButton("0");
cmdZero.setBounds(10,250,50,40);
cp.add(cmdZero);
cmdZero.addActionListener(this);
cmdSign=new JButton("+-");
cmdSign.setBounds(70,250,50,40);
cp.add(cmdSign);
cmdSign.addActionListener(this);
cmdDot=new JButton(".");
cmdDot.setBounds(130,250,50,40);
cp.add(cmdDot);
cmdDot.addActionListener(this);
cmdPlus=new JButton("+");
cmdPlus.setBounds(190,250,50,40);
cp.add(cmdPlus);
cmdPlus.addActionListener(this);
cmdEnter=new JButton("=");

cmdEnter.setBounds(250,250,50,40);
cp.add(cmdEnter);
cmdEnter.addActionListener(this);

setSize(500,500);
setVisible(true);
}//constructor


public void actionPerformed(ActionEvent ae)
{
try
{
if(ae.getActionCommand().equals("0"))
txtScr.setText(txtScr.getText()+"0");
else if(ae.getActionCommand().equals("1"))
txtScr.setText(txtScr.getText()+"1");
else if(ae.getActionCommand().equals("2"))
txtScr.setText(txtScr.getText()+"2");
else if(ae.getActionCommand().equals("3"))
txtScr.setText(txtScr.getText()+"3");
else if(ae.getActionCommand().equals("4"))
txtScr.setText(txtScr.getText()+"4");
else if(ae.getActionCommand().equals("5"))
txtScr.setText(txtScr.getText()+"5");
else if(ae.getActionCommand().equals("6"))
txtScr.setText(txtScr.getText()+"6");
else if(ae.getActionCommand().equals("7"))
txtScr.setText(txtScr.getText()+"7");
else if(ae.getActionCommand().equals("8"))
txtScr.setText(txtScr.getText()+"8");
else if(ae.getActionCommand().equals("9"))
txtScr.setText(txtScr.getText()+"9");
else if(ae.getActionCommand().equals("."))
txtScr.setText(txtScr.getText()+".");


if(ae.getActionCommand().equals("C"))
{
txtScr.setText("");
txtScr.grabFocus();
}
if(ae.getActionCommand().equals("<<"))
{
int len=(txtScr.getText()).length();
String str=txtScr.getText();
txtScr.setText("");

if(len>0)
{
for(int i=0;i<len-1;i++)
{
txtScr.setText(txtScr.getText()+""+(str).charAt(i));
}
}
}

if (ae.getActionCommand().equals("+"))
{
num1=Float.parseFloat(txtScr.getText());
op="+";

txtScr.setText("");
txtScr.grabFocus();

}
else if(ae.getActionCommand().equals("-"))
{
num1=Float.parseFloat(txtScr.getText());
op="-";
txtScr.setText("");
txtScr.grabFocus();
}
else if(ae.getActionCommand().equals("*"))
{
num1=Float.parseFloat(txtScr.getText());
op="*";
txtScr.setText("");
txtScr.grabFocus();
}
else if(ae.getActionCommand().equals("/"))
{
num1=Float.parseFloat(txtScr.getText());
op="/";
txtScr.setText("");
txtScr.grabFocus();
}
else if(ae.getActionCommand().equals("1/x"))
{
num1=Float.parseFloat(txtScr.getText());
num2=(float)(0.0);
op="1/x";

txtScr.grabFocus();
txtScr.setText(String.valueOf(dt.calculate(num1,num2,op)));
}
else if(ae.getActionCommand().equals("s"))
{
num1=Float.parseFloat(txtScr.getText());
num2=(float)(0.0);
op="s";
txtScr.grabFocus();
txtScr.setText(String.valueOf(dt.calculate(num1,num2,op)));
}
else if(ae.getActionCommand().equals("+-"))
{
if(Float.parseFloat(txtScr.getText()) > 0)
txtScr.setText("-"+txtScr.getText());
else
txtScr.setText(Math.abs(Float.parseFloat(txtScr.getText()))+"");
}

if(ae.getActionCommand().equals("="))
{
num2=Float.parseFloat(txtScr.getText());
System.out.println(num1  + "" +num2);
txtScr.setText(String.valueOf(dt.calculate(num1,num2,op)));
}

}
catch(Exception eee)
{}

}//actionPerformed
public static void main(String[]rgs)
 {
new ICalcClient();
}
}

Output:

(B)  Retrieve Time and Date from Server to Client

Code:

Intf.java

import java.rmi.*;

public interface DateTime extends Remote
{
public String getDateTime() throws RemoteException;
}

Impl.java

import java.rmi.*;
import java.rmi.server.*;
import java.util.*;

public class DateTimeImpl extends UnicastRemoteObject implements DateTime
{
public DateTimeImpl() throws RemoteException{}

public String getDateTime() throws RemoteException
{
return (new Date()).toString();
}
       
}

Client.java

import java.rmi.*;
import java.net.*;

public class DateTimeClient{
public static void main(String[] args)
{
try{
DateTime d=(DateTime) Naming.lookup("rmi://localhost/DateTimeService");
System.out.println(d.getDateTime());
}
catch(Exception e)
{
System.out.println("Exception occurred : "+e.getMessage());
}

}
}

Server.java

import java.rmi.*;

public class DateTimeServer
{
public DateTimeServer()
{
System.out.println("Server is Instantiated");
try
{
DateTime d=new DateTimeImpl();
Naming.rebind("rmi://localhost:1099/DateTimeService",d);
}
catch(Exception e)
{
System.out.println("Exception occurred :"+e.getMessage());
}
}
public static void main(String args[]){
new DateTimeServer();
}
}

Output:

(C) Equation Solver

Equation: (a-b)2=a2-2ab+b2


Code:

Equation.java

import java.rmi.*;

public interface Equation extends Remote
{
public double getEquationResult(double a,double b) throws RemoteException;
}

EquationImpl.java

import java.rmi.*;
import java.rmi.server.*;

public class EquationImpl extends UnicastRemoteObject implements Equation
{
public EquationImpl() throws RemoteException{}

public double getEquationResult(double a, double b)throws RemoteException
{
return((a*a)-(2*a*b)+(b*b));
}
}

EquationClient.java

import java.rmi.*;

public class EquationClient
{
public static void main(String args[]){
try{
Equation i =(Equation) Naming.lookup("rmi://localhost:1099/EquationService");
double ans=i.getEquationResult(5,2);
System.out.println(ans);
}catch(Exception e)
{
System.out.println("Exception occurred : "+e.getMessage());
}
}
} 

EquationServer.java

import java.rmi.*;

public class EquationServer
{
public EquationServer(){

System.out.println("Server is Instantiated");

try{
Equation i = new EquationImpl();
Naming.rebind("rmi://localhost:1099/EquationService",i);
}catch(Exception e){
System.out.println("Exception occurred : "+e.getMessage());
}
}

public static void main(String args[])
{
new EquationServer();
}
}

Output: