|Object COBOL Concepts|
Object COBOL extends Micro Focus technology to enable object-oriented (OO) programming in COBOL, while retaining all the dialects and features previously available. This chapter explains:
If you don't want to create OO programs you don't need to read this manual, and can use Micro Focus Object COBOL in the same way you used Micro Focus COBOL.
To enable you to write OO programs in COBOL, MERANT has added the following components and features to the COBOL system:
Object COBOL has a small amount of new syntax - one new verb
(INVOKE), one new data type (OBJECT REFERENCE) and three new types of
Adds support for creation of objects, dynamic message binding, and
inheritance to the COBOL run-time system
A library of pre-defined objects which you can use as a foundation for building your own applications
This book is intended to help you get started programming with Object COBOL as quickly as possible. However, if you are completely new to OO programming you might want to do some background reading to familiarize yourself with the new concepts, and perhaps get some training in Object-Oriented Analysis and Design. There is a list of books in the section Reading List.
The next two sections explain:
The list below shows the basic steps to develop an OO application.
You need to see where inheritance hierarchies will help you to reuse code, and to see which objects will interact with each other and with the messages they will send.
You can use any text editor to code Object COBOL; we recommend the Micro Focus Editor. Alternatively, you can develop and debug your application on NetExpress, and transfer the code to a UNIX platform for production. Object COBOL code is portable between NetExpress and UNIX, except for code developed for:
which are not supported on UNIX.
Steps 1 and 2 are OO analysis, and fall outside of the scope of this book. Some information sources to help you get started are provided in the section Learning More About Object-Orientation. The next section explains how you can use the documentation to help you with steps 3 to 8.
When you start developing OO applications with Object COBOL, you learn about three things:
How OO is handled by Object COBOL. There is very little new syntax to learn.
The development environment for OO will be familiar to any previous users of Micro Focus COBOL.
The Class Library gives you a set of ready-made objects which you can use in your applications. The tutorials in this book give you an introduction to the main types of classes in the Class Library, so that you can get a feel for what is in there. You don't have to know the entire Class Library to begin programming.
This manual is divided into parts for ease of use:
Consists of this chapter and the chapter Object COBOL Concepts. Read the Object COBOL Concepts chapter to get a quick overview of the key points about OO programming and Object COBOL.
The tutorials show you how to send messages, write classes, and start using the supplied class library. The chapter Object COBOL Tutorials briefly describes the subjects covered in the tutorials, and explains how you use them.
Refer to the chapters in this section once you start programming.
The first two chapters Using Objects in Programs and Class Programs deal with using and writing Object COBOL classes. If your interest is to be able to use Object COBOL classes supplied by others as building blocks, you only need to read the chapter Using Objects in Programs, but if you are going to write your own classes you need to read both.
The chapter Extending a Class documents a Micro Focus feature for dynamically adding behavior to a class at run-time.
The chapter Requirements-Based Vocabularies shows you how you can extend Object COBOL syntax and define your own verbs and functions for sending messages.
The chapter Debugging Object COBOL Applications explains some of the extra facilities you will find useful in debugging any program which uses Object COBOL classes and objects.
The chapter Compiling, Linking and Shipping OO Applications supplements the information supplied in the other manuals in your Object COBOL documentation set. It will help you get an application ready for delivery to end-users.
Documents the main frameworks provided in the supplied Object COBOL Class Library. The Class Library is a big subject in its own right; the section Exploring the Class Library later in this chapter will help you to find your way around.
Contains the appendix Descriptions of OO Run-time Switches. This is reference information on switches you can set to alter the behavior of OO applications at run-time.
The glossary contains a list of the new terms introduced by this book.
The Class Library contains public classes and private classes. Private classes are not part of the public interface and are not fully documented - for an explanation of what Micro Focus means by public and private, see the sections Private Interface and Public Interface in the chapter Introduction to the Class Library.
To help you get started with the Class Library, we have provided four sources of information, moving from introductory and "how-to" information, to detailed reference information:
For each class, it gives you a description of its use, and a list of all the public class and instance methods which the class either implements or inherits, except those inherited from Base. All classes inherit the methods in Base, so these are only documented under the description for Base.
The documentation supplied with Object COBOL will help you to start programming in Object COBOL. However, if you are new to OO, learning about the principles of Object-Oriented Design and Analysis (OOD and OOA) will enable you to make the best use of this new technology.
The reading list below suggests some texts you might want to start with. There are also several training organizations who run language-independent courses on OOD and OOA.
MERANT Training also runs Object COBOL programming courses.
This is a short list of texts dealing with Object-Oriented methodologies and technologies.
|Grady Booch:||Object-Oriented Design
Benjamin/Cummings, 1994 ISBN: 0-8053-0091-0
|Ivor Jacobson:||Object-Oriented Software Engineering
Addison-Wesley, 1992 ISBN: 0-201-54435-0
|James Rumbaugh:||Object-Oriented Modeling and Design
Prentice Hall, 1991 ISBN: 0-13-629841-9
|Sally Shlaer and Steve Mellor:||Object-Oriented Systems Analysis: Modeling the
World in Data
Prentice Hall, 1988 ISBN: 0-13-629023-1
|Object Lifecycles: Modeling the World in
Prentice Hall, 1992 ISBN: 0-13-629940-7
|David Taylor:||Object Oriented Information Systems: Planning
John Wiley, ISBN: 0-471-54364-0
Aimed at managers who need to make informed decisions for successful system installation and development.
|Rebecca Wirfs-Brock and B. Wilkerson:||Designing Object-oriented Software|
Copyright © 1999 MERANT International Limited. All rights reserved.
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|Object COBOL Concepts|