RMI-REMOTE METHOD INVOCATION

1. Remote Method Invocation (RMI)
Session 11
Master Java - Level 2/ Session 11 / 1 of 14

2. Session Objectives
 Describe the Java Distributed Model
 Analyse RMI Architeture
 Discuss RMI packages
 Explain how to implement RMI
client and server
Master Java - Level 2/ Session 11/ 2 of 14

3. Distributed Application
 A Distributed application is an application whose
processing is distributed across multiple networked
computers.
 The various models that can be used for developing
distributed applications
 Distributed Component Object Model(DCOM)
 Common Object Request Broker Architecture(CORBA)
 Remote Method Invocation(RMI)
Master Java - Level 2/ Session 11/ 3 of 14

4. Remote Method Invocation (RMI)
The distributed object model used by Java allows objects
in one JVM to invoke methods of objects in a separate
JVM. This is known as RMI.
Java Virtual Machine Java Virtual Machine
Client Object TCP Server Object
Master Java - Level 2/ Session 11/ 4 of 14

5. RMI System Layers
 The RMI system consists of three layers in its
architecture:
 Stub/Skeleton Layer
 Remote Reference Layer
 Transport Layer
Master Java - Level 2/ Session 11/ 5 of 14

6. RMI Architecture
Java Virtual Machine Java Virtual Machine
Client Object Server Object ‘S’
Object ‘S’ Stub Object ‘S’ Skeleton
Remote Reference Remote Reference
Layer Layer
TransportLayer TCP TransportLayer
Master Java - Level 2/ Session 11/ 6 of 14

7. Remote Method Invocation API
 The five packages in RMI API are:
 java.rmi
 java.rmi.registry
 java.rmi.server
 java.rmi.activation
 java.rmi.dgc
We shall be examining the first three in detail
Master Java - Level 2/ Session 11/ 7 of 14

8. The java.rmi Package
 The java.rmi package declares
 The Remote interface
 The MarshalledObject class
 The Naming class
 The RMISecurityManager class
 A number of exceptions that are used with remote
method invocations
Master Java - Level 2/ Session 11/ 8 of 14

9. The java.rmi.registry Package
 The interfaces and class of the java.rmi.registry
package are used to handle remote objects by
name and also to register those remote objects
 The java.rmi.registry package provides
 The Registry interface
 The RegistryHandler interface
 The LocateRegistry class. Master Java - Level 2/ Session 11/ 9 of 14

10. The java.rmi.server Package
 The java.rmi.server package supports both client and
server aspects of RMI like a class implementation of
Remote interface, client stub and server skeleton
 Classes and Interfaces declared are :
 RemoteObject class  Skeleton interface
 RemoteServer class  RMIClassLoader class
 UnicastRemoteObject class  RMISocketFactory class
 RemoteStub class
Master Java - Level 2/ Session 11/ 10 of 14

11. Implementing RMI
 Implement RMI server
 Create Remote Interface
 Create a class that implements the remote interface
 Create stub and skeleton classes
 Copy Remote interface and stub to client
 Create and register remote objcet
 Implement the RMI client
 Call the remote interface by using the ‘lookup()’
method of the Naming class.
Master Java - Level 2/ Session 11/ 11 of 14

12. RMI flow - I
Client Virtual Machine Server Virtual Machine
Client Remote Object 1
Stub Skeleton Server
1. Server Creates Remote Registry Virtual Machine
2
object.
Remote Object
2. Server Registers Remote Registered
object with RMI registry
Master Java - Level 2/ Session 11/ 12 of 14

13. RMI flow - II
Client Virtual Machine Server Virtual Machine
Client Remote Object
Stub Skeleton Server
4
3
3. Client requests object from
Registry Virtual Machine
registry
Remote Object 4. Registry returns remote
Registered reference through interface
Master Java - Level 2/ Session 11/ 13 of 14

14. RMI flow - III
Client Virtual Machine Server Virtual Machine
7
Client Remote Object
5 6 Server
Stub Skeleton
5. Client invokes stub method
Registry Virtual Machine
6. Stub talks to skeleton
Remote Object
Registered 7. Skeleton invokes remote
object method.2/ Session 11/ 14 of 14
Master Java - Level