Download CS 584 Lecture 18

CS 584 Lecture 18
Assignment
» Glenda assignment extended to the
Java RMI Deadline
» No Java RMI Assignment
 Test
» Friday, Saturday, Monday

Java RMI
RMI Programming Steps
Coding the source files
 Compilation and Deployment
 Running

Coding the Source Files

There are at least 3 source files
» Interface definition
» Server Implementation
» Client Implementation
–HTML file if applet
Interface Definition
Interface must be public
 Extends java.rmi.Remote
 Must declare java.rmi.RemoteException
in throws clause

Interface Definition Example
package examples.hello
public interface Hello extends java.rmi.Remote
{
String sayHello() throws java.rmi.RemoteException;
}
Server Implementation
Specifies the remote interface
 Defines the constructor
 Implements methods
 Creates and Installs a security manager
 Creates instances of the remote object
 Registers the remote object with the
RMI remote object registry

Server Implementation
package examples.hello
import java.rmi.*;
import java.rmi.server.UnicastRemoteObject
public class HelloImpl
extends UnicastRemoteObject implements Hello
{
private String name;
Server Implementation
public HelloImpl(String s) throws RemoteException
{
super();
name = s;
}
public String sayHello() throws RemoteException
{
return "Hello World";
}
Server Implementation
public static void main(String[] args)
{
System.setSecurityManager(new RMISecurityManager());
try {
HelloImpl obj = new HelloImpl("HelloServer");
Naming.rebind("//myhost/HelloServer", obj);
System.out.println("Hello Server bound");
catch(Exception e) {
System.out.println("Err: " + e.getMessage);
e.printStackTrace();
}
}
Client Implementation
Obtain a reference to the "HelloServer"
from the server's registry
 Invoke the method on the remote object
 Use the returned results

Client Implementation
package examples.hello
import java.awt.*;
import java.rmi.*;
public class HelloApplet extends java.applet.Applet
{
String message = " ";
Client Implementation
public void init()
{
try {
Hello obj = (Hello)Naming.lookup("//" +
getCodeBase().getHost() + "/HelloServer");
message = obj.sayHello();
}
catch (Exception e) {
System.out.println("Err: " + e.getMessage);
e.printStackTrace();
}
}
Client Implementation
public void paint(Graphics g)
{
g.drawString(message, 25,50);
}
Compilation
Compile the source files using javac
 Generate Stub and Skeleton files
» client side and server side proxies
» generated using rmic on class files

Deployment
RMI is based on packages
 RMI objects need to be in a visible place

Execution
Start the registry on the server
» start rmiregistry
 Start the server using the java interpreter
 Run the applet

For More Information
See Sun's website for a tutorial
» web3.javasoft.com:80/products/jdk/1.1
/docs/guide/rmi/getstart.doc.html
 Remember the test!!!!!
