It's a presentation on Java Remote Method Invocation.

1. GROUP MEMBERS
MD. SHAHRIAR ANWAR (09.02.04.088)
NASHIYED ARAFUL HAQUE (09.02.04.078)
Remote Method Invocation
(RMI)

2. Overview
 Introduction of RMI
 Uses of RMI
 Interfaces and Classes
 RMI Architecture
 RMI Application Overview
 Remote Object and Interface Explained
 A short demonstration of RMI application

3. What is RMI?
 Remote Method Invocation (RMI), allows one host
to run programs on another host that is running a
program on a remote host from a local machine.
In Brief:
 It’s a core JAVA API
 Enables programs calling methods in objects
running on different host even though both
program exists in two physically different hosts.

4. Why We Need RMI?
Let’s think a scenario -
 Suppose you’re an owner of a large company. You’re
company have branches all over the country.
 Now if one of your company branch need to get
services/data from head office, how they’ll do it?
Answer is : RMI
We’ll show you how that work and what it does

5. Interface and Classes in Package java.rmi
RemoteObject
RemoteServer
Activatable UnicastRemoteobject
Remote
Interface Classes

6. RMI Architecture
 The server must first bind its name to
the registry
 The client lookup the server name in
the registry to establish remote
references.
 The Stub serializing the parameters to
skeleton, the skeleton invoking the
remote method and serializing the
result back to the stub.

7. The Stubs and Skeleton
RMI Client Stubs Skeleton RMI Server
Call
Return
 A client invokes a remote method, the call is first forwarded to stub.
 The stub is responsible for sending the remote call over to the
serverside skeleton
 The stub opening a socket to the remote server, marshaling the object
parameters and forwarding the data stream to the skeleton.
 A skeleton contains a method that receives the remote calls, unmarshals
the parameters, and invokes the actual remote object implementation.

8. RMI Application Overview
 RMI applications consist of two separate programs, a
server and a client.
 Server program creates some remote objects, makes
references to these objects accessible, and waits for
clients to invoke methods on these objects.
 Client program obtains a remote reference to one or
more remote objects on a server and then invokes
methods on them.

9. Remote Object
 An object with methods that may be invoked from
a different Java virtual machine than the one
running on a different computer.
 Each remote object implements one or more
remote interfaces that declare which methods of
the remote object can be invoked by the foreign
system.

10. Remote interfaces, Objects and Methods
Remote Object
 Objects with methods that can be invoked across
Java virtual machines are called remote objects
 Remote Object implements Remote Interface
 A Remote Interface extends java.rmi.Remote
interface
 Each method of the interface declares
java.rmi.RemoteException in its throws clause

11. Remote Interface Explained
 Let’s take a sample code snippet
import java.rmi.*;
public interface HomeWork extends Remote {
public String giveMeYourHomeWork( ) throws RemoteException;
}

12. Remote Interface Explained (cont…)
 Java program running on your workstation (e.g. JVM on
you.com) could look up the current HomeWork object in the
RMI registry at remote virtual machine (e.g. JVM on
yourfriend.com).
 The registry would send it a reference to the object running in
remote (yourfriend.com 's) virtual machine.
 Your program could then use this reference to invoke the
giveMeYourHomeWork( ) method.
 The giveMeYourHomeWork( ) method would execute on the
server in remote machine not on your local machine.
However, it would return the String value back to your local
program running in your local machine.

13. A Short RMI Example
 What this program does?
 This is a simple program which pass two integers to Server
through RMI and invoke remote method from Client to
calculate their Sum.
 There are 3 classes and 1 interface
 SumInterface
 SumImpl
 RMIServer
 RMIClient

14. SumInterface.java

15. SumImpl.java

16. RMIServer.java

17. RMIClient.java

18. Compiling and Running from Terminal
Compiling …
After compiling following classes are generated …

19. Generating Stubs and Starting RMI Registry
Generating Stubs and Starting RMI Registry …
After generating Stubs directory looks like …

20. Starting Server and Client
Open a new Terminal and start the server …
Open another new Terminal and start the Client … (You’ll get result immediately)

21. References
 http://www.javacoffeebreak.com/articles/javarmi/ja
varmi.html
 http://docs.oracle.com/javase/7/docs/platform/rmi
/spec/rmi-arch2.html
 http://en.wikipedia.org/wiki/Java_remote_method
_invocation
 http://docs.oracle.com/javase/7/docs/api/java/rmi/
package-summary.html