- Java RMI allows methods to be called remotely between JVMs on different hosts. - For an interface to be remote, it must extend the Remote interface. Remote objects implement remote interfaces and extend UnicastRemoteObject. - Primitive types are passed by value between remote systems, while non-remote objects are serialized and passed by value with references also serialized. Remote objects are passed as remote references called stubs.

1. Java RMI, 17 November 2011

2.  Methods can be called by another JVM on a
different host
 Interface is remote if it extends Remote
 Remote object implements a remote
interface and extends UnicastRemoteObject
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3.  Primitive types are passed by value
 Objects (that are not remote)
 They are serialized and then passed by value.
 At the other end the objects are deserialized
 Any references inside the object are also
serialized
 Remote Objects
 Passed as remote references (stubs)
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4.  Obtain a reference for the remote object
 URL for the remote object is specified as
 rmi://host:port/name
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5. public class HiDunia {
public String sayHalo() {
return "Halo dunia!";
}
public static void main (String args[]) {
String response = this.sayHalo();
System.out.println(response); }
}
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6. public class Halo {
public String sayHalo() {
return "Hello, world!";
}
}
public class HaloDunia {
public static void main (String args[]) {
Halo kelas = new Halo();
String response = kelas.sayHalo();
System.out.println(response); }
}
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7.  Satu address space
 Code segment
 Data segment
 Stack segment
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8.  Proses berbeda
 class Halo
 class HaloDunia
 mungkin berjalan di node yang sama
 atau node berbeda
 Different address space
 stub method
 Remote object
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9.  Mendefinisikan remote interface
 Mengimplementasikan interface (server)
 Buat dan ekspor remote object
 Registrasi remote object dengan Java RMI
registry
 Mengimplementasikan client
 Jalankan server
 Jalankan client
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10. import java.rmi.Remote;
import java.rmi.RemoteException;
public interface Hello extends Remote {
String sayHello() throws RemoteException;
}
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11. import java.rmi.Remote;
import java.rmi.registry.Registry;
import java.rmi.registry.LocateRegistry;
import java.rmi.RemoteException;
import java.rmi.server.UnicastRemoteObject;
public class Server implements Hello {
public Server() {}
public String sayHello() {
return "Hello, world!";
}
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12. public static void main(String args[]) {
try {
Server obj = new Server();
Hello stub = (Hello)
UnicastRemoteObject.exportObject(obj, 0);
// Bind the remote object's stub in the registry
Registry registry = LocateRegistry.getRegistry();
registry.bind("Hello", stub);
System.err.println("Server ready");
} catch (Exception e) {
System.err.println("Server exception: " +
e.toString());
e.printStackTrace();
}
}
}
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13. import java.rmi.registry.LocateRegistry;
import java.rmi.registry.Registry;
public class Client {
private Client() {}
public static void main(String[] args) {
String host = (args.length < 1) ? null : args[0];
try {
Registry registry = LocateRegistry.getRegistry(host);
Hello stub = (Hello) registry.lookup("Hello");
String response = stub.sayHello();
System.out.println("response: " + response);
} catch (Exception e) {
System.err.println("Client exception: " +
e.toString());
e.printStackTrace();
}
}
}
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14. javac –d destDir Server.java
javac –d destDir Client.java
start rmiregistry
java –Djava.rmi.server.codebase=file:destDir/ Server
java –Djava.rmi.server.codebase=file:destDir/ Client
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15.  Default pada port 1099
 start rmiregistry 2011
 Registry reg =
LocateRegistry.getRegistry(2011);
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16.  Implementasikan sebuah aplikasi kalkulator
sederhana dengan RMI
 Client menerima ekspresi matematika (+, x, /, -)
 Server mengimplementasikan method-method
yang sesuai
 Parsing ekspresi matematika dengan
StringTokenizer
 untuk menentukan method apa yang dipanggil
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17.  Kerangka program Client
 Baca ekspresi matematika
 Tokenize, untuk mendapatkan ekspresi
matematik yang digunakan
 Jika operatornya +, panggil method RMI
penjumlahan()
 Jika operatornya x, panggil method RMI
perkalian()
 dst
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18.  Program Server
 Implementasikan method-method untuk operasi
dasar matematika
 int perkalian(int a, int b);
 int pembagian(int a, int b);
 int penjumlahan(int a, int b);
 int pengurangan(int a, int b);
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19.  Waktu pengerjaan
 Dua pekan (30 November 2011, pukul 12.00 WIB)
 By e-mail barliant@gmail.com
 Subject "IKH331 RMI"
 Bonus
 Evaluasi ekspresi yang lebih kompleks
 3+4x2
 (3 + 4) x 2
 Pengumpulan sebelum tenggat waktu
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20.  Java RMI Hello World,
http://download.oracle.com/javase/6/docs/tec
hnotes/guides/rmi/hello/hello-world.html
 Vijay Garg, "Concurrent and Distributed
Programming in Java"
 Source code
http://users.ece.utexas.edu/~garg/jbk.html
 http://tjerdastangkas.blogspot.com/search/la
bel/ikh331
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21. Kamis, 17 November 2011