EXAMPLE
Product.java
------------
import PRODUCT java.rmi.*;
public interface Product extends Remote
{ String getDescription()
throws RemoteException;
}
ProductClient.java
------------------
import java.rmi.*;
import java.rmi.server.*;
public class ProductClient
{ public static void main(String[] args)
{ System.setSecurityManager(new RMISecurityManager());
String ur1 = "rmi://localhost/";
try
{ Product c1 = (Product)Naming.lookup(ur1 + "toaster");
Product c2 = (Product)Naming.lookup(ur1 + "microwave");
System.out.println(c1.getDescription());
System.out.println(c2.getDescription());
}
catch(Exception e)
{ System.out.println("Error " + e);
}
System.exit(0);
}
}
ProductImpl.java
----------------
import java.rmi.*;
import java.rmi.server.*;
public class ProductImpl
extends UnicastRemoteObject
implements Product
{ public ProductImpl (String n)
throws RemoteException
{ name = n;
}
public String getDescription()
throws RemoteException
{ return "I am a " + name + ". Buy me!";
}
private String name;
}
ProductServer.java
------------------
import java.rmi.*;
import java.rmi.server.*;
import sun.applet.*;
public class ProductServer
{ public static void main(String args[])
{ try
{ System.out.println
("Constructing server implementations...");
ProductImpl p1
= new ProductImpl("Blackwell Toaster");
ProductImpl p2
= new ProductImpl("ZapXpress Microwave Oven");
System.out.println
("Binding server implementations to registry...");
Naming.rebind("toaster", p1);
Naming.rebind("microwave", p2);
System.out.println
("Waiting for invocations from clients...");
}
catch (Exception e)
{
System.out.println("Error: " + e);
}
}
}
client.policy
-------------
grant
{ permission java.net.SocketPermission
"*:1024-65535", "connect";
};
Product Program Compile and Run
===============================
Script started on Mon Jul 21 20:02:57 2003
palazzo% javac *.java
palazzo% rmic ProductImpl
palazzo% ls
Product.class ProductImpl.class ProductServer.class
Product.java ProductImpl.java ProductServer.java
ProductClient.class ProductImpl_Skel.class client.policy
ProductClient.java ProductImpl_Stub.class product.run
palazzo% rmiregistry&
[1] 19350
palazzo% java ProductServer&
[2] 19351
palazzo% Constructing server implementations...
Binding server implementations to registry...
Waiting for invocations from clients...
palazzo% java -Djava.security.policy=client.policy ProductClient
I am a Blackwell Toaster. Buy me!
I am a ZapXpress Microwave Oven. Buy me!
palazzo% date
Mon Jul 21 20:05:18 PDT 2003
palazzo%
script done on Mon Jul 21 20:05:28 2003
---------------------------------------------------------------------------
PRODUCER-CONSUMER MESSAGE EXAMPLE
MessageQueue.java
-----------------
import java.util.*;
import java.rmi.*;
public interface MessageQueue
extends java.rmi.Remote
{
public void send (Object item) throws
java.rmi.RemoteException;
public Object receive() throws
java.rmi.RemoteException;
}
MessageQueueImpl.java
---------------------
import java.util.*;
import java.rmi.*;
public class MessageQueueImpl
extends java.rmi.server.UnicastRemoteObject
implements MessageQueue {
public MessageQueueImpl()
throws RemoteException {
queue = new Vector();
}
public synchronized void send(Object item)
throws RemoteException {
queue.addElement(item);
System.out.println("Producer entered " + item +
" size = " + queue.size());
}
public synchronized Object receive()
throws RemoteException {
Object item;
if (queue.size() == 0) return null;
else {
item = queue.firstElement();
queue.removeElementAt(0);
System.out.println("Consumer removed " + item +
" size = " + queue.size());
return item;
}
}
public static void main (String args[]) {
try {
MessageQueue server = new MessageQueueImpl();
Naming.rebind("MessageServer", server);
System.out.println("Server Bound");
}
catch(Exception e) {
System.err.println(e);
}
}
private Vector queue;
}
Factory.java
------------
import java.util.*;
import java.rmi.*;
public class Factory
{
public Factory() {
// remote object
MessageQueue mailBox;
System.setSecurityManager(new RMISecurityManager());
try {
mailBox = (MessageQueue)Naming.lookup
("rmi://127.0.0.1/MessageServer");
Producer ProducerThread = new Producer(mailBox);
Consumer ConsumerThread = new Consumer(mailBox);
ProducerThread.start();
ConsumerThread.start();
}
catch (Exception e) {
System.err.println(e);
}
}
public static void napping() {
int sleepTime = (int)(NAP_TIME * Math.random());
try { Thread.sleep(sleepTime*1000); }
catch (InterruptedException e) { }
}
public static void main(String args[]) {
Factory client = new Factory();
}
private static final int NAP_TIME = 5;
}
Producer.java
-------------
import java.util.*;
class Producer extends Thread
{
public Producer(MessageQueue m) {
mbox = m;
}
public void run() {
Date message;
while (true) {
Factory.napping();
message = new Date();
try {
mbox.send(message);
}
catch (Exception e) {
System.err.println(e);
}
}
}
private MessageQueue mbox;
}
Consumer.java
-------------
import java.util.*;
class Consumer extends Thread
{
public Consumer(MessageQueue m) {
mbox = m;
}
public void run() {
Date message;
while (true) {
Factory.napping();
try {
message = (Date)mbox.receive();
if (message != null) {
// consume the item
;
}
}
catch (Exception e) {
System.err.println(e);
}
}
private }
MessageQueue mbox;
}
client.policy
-------------
grant
{ permission java.net.SocketPermission
"*:1024-65535", "connect";
};
----------------------------------------------------------------------------------
Message Program Compile and Run
===============================
palazzo% javac *.java
Consumer.class MessageQueueImpl.java
Consumer.java MessageQueueImpl_Skel.class
Factory.class MessageQueueImpl_Stub.class
Factory.java Producer.class
MessageQueue.class Producer.java
MessageQueue.java show.run
MessageQueueImpl.class
palazzo%
palazzo% rmic MessageQueueImpl
palazzo% rmiregistry &
[1] 11774
palazzo% java -Djava.security.policy=client.policy MessageQueueImpl&
[2] 11782
palazzo% Server Bound
palazzo% java -Djava.security.policy=client.policy Factory
Producer entered Sat Feb 10 15:53:13 PST 2001 size = 1
Consumer removed Sat Feb 10 15:53:13 PST 2001 size = 0
Producer entered Sat Feb 10 15:53:16 PST 2001 size = 1
Consumer removed Sat Feb 10 15:53:16 PST 2001 size = 0
Producer entered Sat Feb 10 15:53:17 PST 2001 size = 1
^Cpalazzo%
palazzo%
--------------------------------------------------------------------------
Bank ATM Example
----------------
//
// ATM.java
//
import java.lang.*;
import java.rmi.*;
public interface ATM extends Remote
{
boolean searchpw (String pw) throws RemoteException;
double deposit(int acc, double amount) throws RemoteException;
double withdraw(int acc, double amount) throws RemoteException;
double balance(int acc) throws RemoteException;
}
//
// Server.java
//
import java.lang.*;
import java.io.*;
import java.net.*;
import java.util.*;
import java.rmi.*;
import java.rmi.server.*;
public class Server extends UnicastRemoteObject
implements ATM
{
public static final int N=10;
private boolean found;
private String pw;
private double accArr[];
private int i;
public static void main(String [] args)
{
// System.setSecurityManager(new RMISecurityManager());
try
{
Server server=new Server();
Naming.rebind("ATM", server);
System.out.println("ATM is ready...");
}
catch (RemoteException re)
{
...
}
catch (MalformedURLException me)
{
...
}
public Server()
throws RemoteException
{
super();
pw="888";
accArr=new double[N];
for(i=0; i<N; i++)
accArr[i]=0;
}
public boolean searchpw (String pw) throws RemoteException
{
if(pw.equals(this.pw))
found=true;
return found;
}
public synchronized double deposit(int accNum, double amount) throws RemoteException
{
System.out.println("Deposit "+amount+" to ACC: "+accNum);
for(i=0; i<N; i++)
{
if(accNum>0&&accNum<11)
{
accArr[accNum-1]+=amount;
System.out.println("ACC: "+accNum+"\tNew Bal: " +
accArr[accNum-1]);
System.out.println();
return accArr[accNum-1];
}
}
return -1;
}
public synchronized double withdraw(int accNum, double amount) throws RemoteException
{
..
}
}
//
// Client.java
//
import java.lang.*;
import java.io.*;
import java.util.*;
import java.rmi.*;
import java.net.*;
public class Client
{
private ATM atm;
private String pw;
private int acc1;
private int acc2;
private double amount;
private double result1;
private double result2;
private boolean found;
private char c;
public static void main(String [] args)
{
System.setSecurityManager(new RMISecurityManager());
String stemp;
if (args.length>0) stemp=args[0];
else stemp="localhost";
Client client=new Client(stemp);
client.service();
}
public Client(String server)
{
connect(server);
}
public void connect(String server)
{
try
{
String stemp;
if (server.indexOf("//")>=0) stemp=server;
else stemp="rmi://"+server+"/ATM";
atm=(ATM)Naming.lookup(stemp);
}
catch (RemoteException re)
{
System.err.println(re.getMessage());
}
catch (NotBoundException ne)
{
System.err.println(ne.getMessage());
}
catch (IOException ie)
{
System.err.println(ie.getMessage());
}
}
public void service()
{
try
{
BufferedReader stdin=new BufferedReader (
new InputStreamReader (System.in));
do
{
System.out.print("Please enter password: ");
pw=stdin.readLine().trim();
found=atm.searchpw(pw);
if(found)
{
while(true)
{
System.out.println("Transaction Types: D = Deposit\n"
+"\t\t W = Withdraw\n"
+"\t\t T = Transfer\n"
+"\t\t B = Balance\n"
+"\t\t Q = Quit");
System.out.println("Please enter your transaction:");
c=stdin.readLine().charAt(0);
System.out.flush();
switch(c)
{
case 'D':
System.out.print("Enter ACCNUM: ");
acc1=Integer.parseInt(stdin.readLine().trim());
System.out.print("Enter amount: ");
amount=Double.parseDouble(stdin.readLine().trim());
result1=atm.deposit(acc1, amount);
if(result1>=0)
System.out.println("ACC: "+acc1
+"\t\tNew Bal: "+result1);
else
System.out.println("ACC not found.");
break;
....
}
}
`}
} while(!found);
}
catch (Exception e) {}
}
}
client.policy file
------------------
grant
{
permission java.security.AllPermission;
};