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.helloimport 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!!!!!