[ Syllabus ] [ Teaching materials ] [ References ]

Distributed Object-Oriented Systems

Motivation:

Constant innovation in computing industry has brought large mass of sophisticated application. A set of problems has been derived from the sophistication for both developers and users. Applications are time-consuming to develop, difficult and costly to maintain. Functionality and data of one application generally are not available to other applications even if they are running on the same computer. Very often the same services provided by the operating system and the network are different. Programming models are also inconsistent. They are vary widely depending on whether the service is coming from a provider in the same address space as the client program, from a separate process on the same computer, from the operating system, or from a provider running on a separate computer across the network.

Another consequence of the increasing software complexity is the need for a new approach of developing software featured by

the object-oriented concepts to re-use existing solutions, and to facilitate new designs of more self-sufficient software components;
the client-server computing to communicate between powerful workstations and network servers;
the distributed computing to provide a single system image to users and applications and to permit use of services in a networked environment regardless of location, computer architecture, or implementation environment.

Responding to the increasing demand, a variety of distributed frameworks have been started to develop. Such frameworks facilitate the creation of collaborative distributed applications. Maybe the best-known representatives of such distributed framework is the CORBA

The Common Object Request Broker Architecture (CORBA) is structured to allow integration of a wide variety of object systems, developed by the Object Management Group (OMG).

The client is the entity that wishes to perform an operation on the object and the object implementation is the code and data that actually implements the object. The ORB (Object Request Broker) is responsible for all of the mechanisms required to find the object implementation for the request, to prepare the object implementation to receive the request, and to communicate the data making up the request. The interface the client sees is completely independent of where the object is located, what programming language it is implemented in, or any other aspect which is not reflected in the object's interface.

To make a request, the client can use the Dynamic Invocation interface (the same interface independent of the target object's interface) or an OMG Interface Definition Language (OMG IDL) stub (the specific stub depending on the interface of the target object). The client can also directly interact with the ORB for some functions.

The ORB locates the appropriate implementation code, transmits parameters and transfers control to the object implementation through an IDL skeleton or a dynamic skeleton. Skeletons are specific to the interface and the object adapter. In performing the request, the object implementation may obtain some services from the ORB through the Object Adapter. When the request is complete, control and output values are returned to the client.

ORB is not required to be implemented as a single component, but rather it is defined by its interfaces. Any ORB implementation that provides the appropriate interface is acceptable. The ORB Core is that part of the ORB that provides the basic representation of objects and communication of requests. CORBA is designed to support different object mechanisms, and it does so by structuring the ORB with components above the ORB Core, which provide interfaces that can mask the differences between ORB Cores.

Aim:

This course is intended to bring together the student's knowledge of object-oriented software development and networking and to extend it into the creation of distributed object-oriented systems. We set the objective to develop a new course to introduce CORBA both on theoretical and practical level.

Objectives:

On completion of this course student will be able to:

use Java programming language
understand the client-server computation model
understand the CORBA concepts
design and implement simple distributed applications

Approach:

The theoretical aspects of this topic will be covered in lectures to convey the fundamental issues. Practical exercises will concentrate on the use of framework and creation applications. The particular tools to be used (ORBIX, Java, etc) will be defined after evaluating experiencies are from TEMPUS partners.

Prerequisits:

At least middle level on Operating systems, Computer Networks, Software Engineering and programming practice on an OO language (C++).

Detailed syllabus:

Getting started with Java

Java basics
Variables, operators, arrays, control str
Class concepts
methods, access, statics, inheritence
Exception handling
Interfaces
Bags

Java classes

Java.lang
Java.util
Java.io
Java.awt
Parallelism
threads, scheduling
Java.net

Advanced Java programming

Applets
Persistency
Database programming
JavaBeans
Component model

Client/Server with Distributed Objects

Distributed Application Concepts
Distributed Object Concepts
Components
Object life cycle
Remote Method Invocation
The RMI Registry
Serializing Objects

Introduction to CORBA

CORBA Architecture Overview
The Object Management Architecture
CORBA Structure
CORBA Services
CORBA Facilities

The first CORBA program

Requirement Specification
Development Process
CORBA IDL and Java
The Servant Program
The Server Program
The Client as a Java Application
The Client as an Applet

Interface Definition Language

Introduction to CORBA IDL
Defining IDL Interfaces
Overview of the IDL data types
IDL to Java mapping
Using and implementing IDL interfaces
ORB interoperability

Advanced CORBA programming

Exception handling
Using inheritance of IDL interfaces
Callbacks from Servers to Clients
Type any
Dynamic Invocation Interface
The interface repository

Documents

Getting started with Java by Péter Kacsuk
4 slides Zipped PowerPoint 8k
8 slides Zipped PowerPoint 10k
26 slides Zipped PowerPoint 25k
33 slides Zipped PowerPoint 21k
Java classes by Péter Kacsuk
36 slides Zipped PowerPoint 58k
23 slides Zipped PowerPoint 29k
Advanced Java programming by József Kovács
22 slides Zipped PowerPoint 114k
28 slides Zipped PowerPoint 73k
Client/Server with Distributed Objects
24 pages WinZipped-Winword7(27k) by dr. Zoltán László, dr. Károly Kondorosi
Introduction to CORBA
32 pages WinZipped-Winword7(26k) by dr. Zoltán László
The first CORBA program
24 pages WinZipped-Winword7(25k) by dr. Zoltán László
Interface Definition Language
20pages WinZipped-Winword7 (19k) by dr. Zoltan Laszls, Balazs Goldschmidt
Advanced CORBA programming
29pages WinZipped-Winword7 (22k) by dr. Zoltan Laszls, Balazs Goldschmidt
12 CORBA Sample Programs by dr. Zoltán László

Indicative text:

Robert Orfali, Dan Harkey, Jeri Edwards: The Essential Client/Server Survival Guide
Wiley, 1996

Robert Orfali, Dan Harkey, Jeri Edwards: The Essential Distributed Objects Survival Guide
Wiley, 1995

Alan Pope: CORBA Reference Guide
Addison-Wesley, 1998

Ron Ben-Natan: CORBA - A Guide to Common Object Request Broker Architecture
McGraw-Hill, 1995

Waqar Sadiq, Fred Cummins: Building Distributed, Object-Oriented Business Systems Using Corba
SIGS, 1997

Jon Siegel et al: CORBA Fundamentals and Programming
Wiley, 1996

Robert Orfali, Dan Harkey: Client/Server Programming with Java and CORBA
Wiley, 1998

Sean Baker: CORBA Distributed Objects using Orbix
ACM Addison Wesley, 1997

Thomas J. Mowbray, Ron Zahavi: The Essential CORBA: Systems Integration Using Distributed Objects
Wiley, 1995

Andreas Vogel, Keith Duddy: Java Programming With CORBA 2nd Ed.
Wiley, 1998