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!!!!!
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