Written by two leading experts and approved by SAP's ABAP Language Group, this guide provides an in-depth and comprehensive introduction to SAP application programming for Release 4.6. Includes two CDs carrying a fully operational SAP Basis System, and containing all the example programs from the book.

Dr Horst Keller is a member of SAP's ABAP Language Group and one of the authors of the ABAP Objects official documentation.
Sascha Krüger is a certified SAP consultant and project leader with leading German IT and telecomms consultancy SHS Informationssysteme AG (www.shs.de).

Preface from SAP

xi

Preface from SHS Informationssysteme AG

xii

Foreword

xiii

Introduction

What is ABAP Objects?

1

(2)

Target readership

3

(1)

How to read this book

3

(3)

How to use this book in practice

6

(2)

Syntax conventions

8

(2)

A Practical Introduction

Introduction

10

(1)

First steps with the ABAP Workbench

11

(11)

Getting started with the ABAP Workbench

11

(5)

Working with the Object Navigator

16

(6)

The first program

22

(37)

ABAP syntax

22

(2)

General program structure

24

(1)

Insert: a ``Hello World!'' program

25

(4)

View of the first application program

29

(1)

Copying programs

29

(2)

Creating a screen

31

(6)

Dialog modules in the ABAP program

37

(2)

Working with the ABAP Debugger

39

(1)

Creating a GUI status

40

(3)

The data interface between the program and screen

43

(1)

A classical main program

44

(1)

Creating a class

45

(2)

Working with objects

47

(1)

Working with global classes

48

(4)

Final steps

52

(3)

Resources

55

(2)

Final comments on the practical introduction

57

(2)

Basics of ABAP Programming

The environment of an ABAP program

59

(2)

The architecture of an SAP System

59

(2)

ABAP programs in the client-server architecture

61

(3)

The SAP Basis System

62

(1)

The ABAP runtime environment

63

(1)

ABAP programs in the runtime environment

64

(20)

ABAP program structure

64

(5)

Processing blocks

69

(4)

Program types

73

(3)

Screens

76

(1)

Program execution

76

(6)

Calling programs internally

82

(2)

Ending ABAP programs

84

(1)

Memory organization of ABAP programs

84

(3)

Basic ABAP Language Elements

Introduction

87

(1)

Data types and data objects

88

(36)

Introduction to the ABAP type concept

88

(2)

The ABAP type hierarchy

90

(1)

Built-in elementary data types

91

(5)

Data types and data objects local to the program

96

(8)

Data types in the ABAP Dictionary

104

(9)

Flat and deep data types

113

(1)

Generic data types for typings

114

(1)

Data objects in detail

115

(9)

Operations and expressions

124

(18)

Assigning values

124

(2)

Type conversions

126

(5)

Numeric operations

131

(6)

Logical expressions

137

(5)

Control structures

142

(5)

Conditional branches

142

(2)

Loops

144

(3)

Processing character strings

147

(8)

Operations with character strings

147

(5)

Comparing character strings

152

(2)

Addressing subfields

154

(1)

Field symbols and data references

155

(14)

Field symbols

156

(8)

Data references

164

(5)

Internal tables

169

(21)

Defining internal tables

170

(5)

Working with internal tables

175

(12)

Internal tables with header rows

187

(2)

Extract datasets

189

(1)

Error handling in ABAP programs

190

(6)

Statically identifiable errors

191

(1)

Runtime errors

192

(4)

The ABAP Programming Models

Introduction

196

(1)

The classical (procedural) programming model

197

(32)

Modularization

197

(23)

Excursion: source code modularization

220

(4)

Visibility and lifetime of data

224

(5)

The object-oriented programming model

229

(33)

How do we define object-orientation?

229

(3)

Classes

232

(6)

Objects and object references

238

(12)

More on defining and calling methods

250

(12)

Summary and outlook

262

(1)

Advanced Concepts of Object-Oriented Programming with ABAP Objects

Introduction

263

(1)

Inheritance

264

(31)

Basic principles

264

(2)

Syntax for subclasses

266

(2)

Visibility sections and namespaces in inheritance

268

(1)

Method redefinition

269

(2)

Abstract classes and methods

271

(2)

Final classes and methods

273

(1)

Static components in inheritance

273

(1)

Constructors in inheritance

274

(5)

Object references in inheritance

279

(8)

Polymorphism through inheritance

287

(8)

Interfaces

295

(21)

Basic principles

295

(1)

Definition of interfaces

296

(1)

Implementing interfaces in classes

296

(4)

Composing interfaces

300

(2)

Alias names for interface components

302

(2)

Interface references

304

(8)

Polymorphism through interfaces

312

(3)

Interfaces and inheritance

315

(1)

Events

316

(9)

Defining and triggering events

318

(3)

Handling events

321

(4)

Global classes and interfaces

325

(11)

Class pools and interface pools

326

(2)

Creating global classes

328

(6)

Testing global classes

334

(1)

Using global classes

334

(2)

Programming Screens

General screens

336

(44)

What are screens?

336

(2)

Defining screens

338

(8)

Calling screens and screen sequences

346

(4)

User actions on screens

350

(6)

Dialog moudule and data transport

356

(3)

Input checks

359

(3)

Field and input helps

362

(5)

An example transaction

367

(13)

Selection screens

380

(21)

What are selection screens?

380

(3)

Why selection screens?

383

(1)

Defining selection screens

384

(7)

Calling selection screens

391

(2)

Selection screen processing

393

(4)

User actions on selection screens

397

(4)

Classical lists

401

(25)

What are classical lists?

401

(1)

Classical lists prior to the advent of ABAP Objects

402

(1)

Classical lists in ABAP Objects

403

(2)

Creating classical lists

405

(5)

Displaying classical lists

410

(4)

User actions on classical lists

414

(2)

Classical list processing and detail lists

416

(2)

Example of classical list processing

418

(3)

Sending lists to the SAP spool system

421

(5)

Messages

426

(4)

Creating messages

426

(1)

Sending messages

426

(2)

Message Processing

428

(2)

Advanced screen techniques

430

(37)

Context menus you program yourself

430

(2)

Drop-down boxes

432

(3)

Classical controls

435

(8)

GUI controls

443

(24)

Working with External Data

Database access

467

(41)

Introduction

467

(2)

Defining database tables in the ABAP Dictionary

469

(1)

Editing data with Open SQL

470

(28)

Consistent data retention

498

(7)

Special sections on database access

505

(3)

File interfaces

508

(4)

Files on the application server

509

(1)

Files on the presentation server

510

(2)

Storing data as clusters

512

(6)

Data clusters in the ABAP Memory

513

(2)

Data clusters in database tables

515

(2)

Data clusters in cross-transaction application buffers

517

(1)

Authority checks

518

(4)

Authorizations and authorization objects

518

(1)

Evaluating authorization objects

519

(3)

APPENDICES

Appendix A

522

(15)

A.1 The key flight data model tables

522

(4)

A.2 Glossary

526

(6)

A.3 ABAP system fields

532

(5)

Appendix B Literature

537

(2)

Appendix C Installing the SAP Mini Basis System

539

C.1 System requirements

539

(1)

C.2 Preliminary remark

539

(1)

C.3 Installing the application server and the database

540

(1)

C.4 Installing the SAP GUI (front end)

541

(1)

C.5 Starting the SAP System

541

(1)

C.6 Configuring the SAPLogon and calling the SAP GUI

541

(1)

C.7 Logging on to the SAP System

542

(1)

C.8 Generating example data

542

(1)

C.9 Linking the Basis Documentation to the SAP Library

542

(1)

C.10 License

542

What is included with this book?

The New copy of this book will include any supplemental materials advertised. Please check the title of the book to determine if it should include any access cards, study guides, lab manuals, CDs, etc.

The Used, Rental and eBook copies of this book are not guaranteed to include any supplemental materials. Typically, only the book itself is included. This is true even if the title states it includes any access cards, study guides, lab manuals, CDs, etc.

From SAP ABAP, the programming language of SAP for business applications, is a language with a long-standing tradition. Having started off over 20 years ago as a reporting language in the mainframe world and having developed between 1985 and 1995 into a complete 4GL with SQL integration and language support for dialog and transaction programming, ABAP is now a modern object-oriented, statically typed yet flexible, portable and universally applicable programming language offering particular support for control- and web-based applications. However, ABAP is more than just a language. It is embedded within a complete development environment with all the editors, tools and repositories needed for large and complex software development projects. A large number of services contained in SAP's application server middleware infrastructure can also be addressed readily and independently of a particular platform. I am delighted that the two authors, Horst Keller and Sascha Kruuml;ger, have taken it upon themselves to portray the object-oriented basic structure of modern ABAP alongside the full scope of the programming concepts developed over time in ABAP. Within a single book they offer the reader the distinct advantage of being able to find descriptions of both the new concepts of object-oriented development with ABAP Objects and the older technologies of earlier releases -- a knowledge of which remains essential due to the volume of ABAP code still in existence. I hope that this book will bring all readers further joy and success in programming in ABAP. Walldorf, August 2000 Andreas Blumenthal Development Manager ABAP Language SAP AG From SHS Informationssysteme AG Dear Reader As a member of the board of SHS Informationssysteme AG it is a particular pleasure for me that our employee Sascha Kruuml;ger has found time in his busy schedule to publish the present book on ABAP Objects together with Dr Horst Keller. Practical and customer-driven implementation based on a thorough theoretical grounding in technological developments as well as dedication is the sole basis for any successful project. In the past SAP has played a significant part in the development of standard ERP software and will, in particular through mySAP.com, continue to do so in the future. From the position of our company, SAP's development in CRM (Customer Relationship Management) with new technological and strategic market orientation is of particular interest in this respect. Following the ERP boom of the past two decades, these customer-oriented systems are now in widespread use throughout companies -- above all in the telecommunications industry with its enormous growth in new customers. Anyone wishing to be successful in this kind of market must come to terms with the SAP Basis technology in order to integrate CRM systems in their existing IT landscape. As many leading companies implement the SAP System, this requires innovative concepts. Not least through the use of EAI (Enterprise Application Integration) tools, object-orientation is being increasingly established as the standard in integration. With ABAP Objects, SAP is intensifying its support of object-oriented (outbound) development and thereby allowing the seamless integration of different object models such as DCOM and CORBA. The present book by Dr Horst Keller and Sascha Kruuml;ger is a