This book deals with the most important ways to develop interfaces for R/3 systems and external software. The primary focus is on the RFC Library.Newer technical approaches used by SAP are also addressed, which include the recent Business Application Programming Interface (BAPI) technology and Java Connector (JCo).
Contents
Introduction 11
1 The Basics of R/3 System Architecture 15
1.1 The Application Server .................................................................................... 16
1.2 The Dialog Process ........................................................................................... 18
1.3 The Update Task ............................................................................................... 20
1.4 The Enqueue Process ....................................................................................... 21
1.5 The Gateway Server ......................................................................................... 23
1.6 Distributed Load Systems and the Message Server .................................. 26
1.7 The RFC Interface Within the R/3 System ................................................... 28
2 The Basics of the ABAP Programming
Language 31
2.1 The ABAP Development Environment .......................................................... 32
2.2 Creating Database Tables ............................................................................... 36
2.2.1 The Data Dictionary .......................................................................... 36
2.2.2 Relationships Between Domains, Data Elements, and Tables ..... 37
2.2.3 Create a Domain ................................................................................ 38
2.2.4 Create a Data Element ...................................................................... 40
2.2.5 Create a Transparent Table ............................................................... 41
2.2.6 Maintaining Data Records Using the Data Browser ...................... 44
2.3 A Simple Program ............................................................................................ 44
2.4 ABAP Data Types and Variable Declaration ................................................ 48
2.5 Elementary Programming Statements in ABAP .......................................... 52
2.5.1 Value Assignments ............................................................................ 52
2.5.2 Branches ............................................................................................. 54
2.5.3 Loops ................................................................................................... 55
2.5.4 Access to Internal Tables .................................................................. 56
2.5.5 Access to Database Tables ................................................................ 57
2.5.6 Configuration of Selection Screens ................................................. 60
2.6 Creating Function Modules ............................................................................ 61
2.7 Coding Conventions in This Book ................................................................. 68
3 Introduction to Programming
with the RFC API 71
3.1 The Task for the First Example ....................................................................... 72
3.2 Programming the SAP Function Modules .................................................... 73
3.3 Programming the Client .................................................................................. 75
3.3.1 The Configuration of the main() Function ...................................... 76
3.3.2 Open a Connection to the R/3 System ........................................... 79
3.3.3 Calling Up Function Modules in the R/3 System .......................... 85
3.4 Frequent Errors on the Client Side ................................................................ 91
3.5 Overview of the Functions and Structures Used ........................................ 93
3.6 From an RFC Function Call to the Function Module ................................. 93
3.7 Programming the External Server .................................................................. 96
3.7.1 Configuring the main() Function for an External Server ............... 97
3.7.2 Open a Connection with the R/3 System ....................................... 99
3.7.3 Implementing the Message Loop .................................................... 103
3.7.4 Implementing the Server Services ................................................... 104
3.7.5 Setting Up the Connection to the R/3 System .............................. 111
3.7.6 Programming the ABAP Client ......................................................... 114
3.8 Frequent Errors on the Server Side ............................................................... 115
3.9 Functions Used ................................................................................................. 116
4 The Basics of RFC Programming 117
4.1 Type Mapping and Data Aggregates ............................................................ 117
4.1.1 Generic Data Types ........................................................................... 117
4.1.2 The Character Data Types ................................................................. 119
4.1.3 Numeric Strings ................................................................................. 122
4.1.4 The Case of Packed Numbers .......................................................... 124
4.1.5 Final Overview of Type Mapping .................................................... 128
4.2 Working with Structures ................................................................................. 130
4.3 Working with Internal Tables ........................................................................ 136
4.3.1 Creating an Internal Table in an External Program ........................ 139
4.3.2 Administration of Data Records in an Internal Table .................... 142
4.3.3 Reading and Writing Data Records in an Internal Table ............... 144
4.3.4 Overview of the Functions for Internal Tables .............................. 148
4.4 The Message Loop ........................................................................................... 148
4.5 Alternatives for Logging on to an R/3 System ............................................ 151
4.5.1 Working With a Configuration File ................................................. 152
4.5.2 Working with Load Balancing .......................................................... 153
4.5.3 Working with the RfcOpen Function .............................................. 154
5 Troubleshooting 157
5.1 The ABAP Debugger ........................................................................................ 157
5.2 The BREAK Statement ..................................................................................... 160
5.3 The Gateway Monitor ...................................................................................... 161
5.4 The RFC Trace ................................................................................................... 162
5.4.1 Structure of the Trace File for an External Client .......................... 164
5.4.2 Structure of the Trace File for an External Server ......................... 166
5.4.3 Traces Using Transaction ST05 ......................................................... 167
5.5 The RFC Generator ........................................................................................... 169
5.5.1 Structure of the Client Program Generated ................................... 171
5.5.2 Structure of the Server Program Generated .................................. 174
5.5.3 Macros for Setting and Reading Values .......................................... 175
5.6 SAP Test Programs ........................................................................................... 175
6 Advanced Techniques 181
6.1 Return Calls from the Server .......................................................................... 181
6.2 Automatic Creation of a Structure Description .......................................... 190
6.3 Transactional Remote Function Calls ........................................................... 196
6.3.1 The R/3 System as tRFC Client ........................................................ 198
6.3.2 Programming a Transactional RFC Server ....................................... 201
6.3.3 Transactional RFC Client ................................................................... 206
6.4 Queue RFCs ...................................................................................................... 211
6.4.1 Administration of qRFCs in the R/3 System ................................... 212
6.4.2 Developing a qRFC Client in the R/3 System ................................ 217
6.4.3 Developing an External qRFC Client ............................................... 221
6.4.4 tRFC and qRFC Calls—Conclusion .................................................. 226
6.5 Error Messages from an External Server ...................................................... 227
6.5.1 Error Messages from a Synchronous Server ................................... 227
6.5.2 Error Messages from the tRFC and qRFC Servers ......................... 231
6.6 Parallel Processing ........................................................................................... 233
6.6.1 Multitasking and Multithreading ..................................................... 234
6.6.2 Creating and Exiting Threads ........................................................... 235
6.6.3 The Basics of Synchronization .......................................................... 237
6.6.4 Synchronization Objects ................................................................... 242
6.6.5 Advantages of Parallel Processing in RFC Programming .............. 244
6.6.6 Implementing Parallel Processing in External Servers ................... 246
7 The Business Object 253
7.1 Business Object—Close to the Object ......................................................... 253
7.2 Structure of the Business Object .................................................................. 256
7.3 The Structure of the Business Object Builder ............................................. 261
7.4 Creating the Object Key .................................................................................. 264
7.5 Methods of the Business Object ................................................................... 266
7.5.1 Instance-Dependent Methods ......................................................... 267
7.5.2 Implementation of Methods Using ABAP Program Forms ........... 269
7.5.3 Creating a Method ............................................................................ 270
7.6 Object Release and the Business Object Repository ................................. 276
7.7 Guidelines for Developing API Methods ..................................................... 278
7.8 Possibilities for Activation .............................................................................. 280
8 Calling BAPIs from Clients 283
8.1 What Are COM and ActiveX? ......................................................................... 283
8.2 “What Is Your Name?” or an Introduction to the Use of
ActiveX Controls ............................................................................................... 287
8.2.1 The SAP BAPI Control ....................................................................... 287
8.2.2 Opening a Connection with the R/3 System ................................. 289
8.2.3 Calling the Business Object Method ............................................... 291
8.2.4 What Is a BAPI Proxy Object Anyway? ........................................... 295
8.3 Naming Conventions During Programming ................................................. 297
8.4 Wrapping the BAPI Proxy Object .................................................................. 298
8.5 A Better Method for Setting Up a Connection to the R/3 System .......... 301
8.5.1 Integrating the Logon Control into the Client ............................... 304
8.5.2 Events of the SAPLogonControl Class ............................................. 306
8.5.3 Recognizing a Disconnection ........................................................... 308
8.6 Concepts for Creating Data Aggregates ....................................................... 310
8.7 The SAP TableFactory Control in Detail ....................................................... 313
8.8 Administering Structures with the SAP TableFactory Control ................. 314
8.8.1 Accessing Data in Structures ............................................................ 315
8.8.2 Note When Working with Structures! ............................................ 316
8.9 Working with Tables ........................................................................................ 318
8.9.1 The Class Hierarchy for Working with Tables ................................ 318
8.9.2 Important Attributes of the Table Class .......................................... 319
8.9.3 Structure of the Example Programs ................................................. 320
8.9.4 Reading Data Records in a Table ..................................................... 321
8.9.5 Changing Data Records ..................................................................... 325
8.9.6 Alternatives for Creating the Field Description ............................. 326
8.10 Visualization of the Table Contents .............................................................. 328
8.10.1 Hierarchy of the Classes of the TableView Control ....................... 330
8.10.2 Specifying the Layout of the Data Grid .......................................... 331
8.10.3 Accessing the Cells in a Data Grid ................................................... 334
8.10.4 Specifying the Data Source for the Data Grid ................................ 339
8.10.5 Concepts for Inserting and Deleting Rows and Columns ............. 343
8.10.6 Working with the Clipboard ............................................................ 346
9 SAP and Java 349
9.1 The SAP Java Connector .................................................................................. 351
9.1.1 Basics of the JCo ................................................................................ 351
9.1.2 Ways of Using the JCo ...................................................................... 352
9.1.3 The JCo Package ................................................................................ 353
9.1.4 JCo Releases ....................................................................................... 354
9.2 Using the JCo .................................................................................................... 354
9.2.1 Basic Structure of a JCo Application ............................................... 354
9.2.2 Connection Setup .............................................................................. 354
9.2.3 Running the RFC Modules ............................................................... 356
9.2.4 Access to Data and Tables ................................................................ 359
9.2.5 Complete Example Program ............................................................ 360
9.2.6 Troubleshooting and Tracing ........................................................... 366
9.2.7 Closing Remarks ................................................................................ 368
9.3 The Future of the SAP Java Interface ............................................................ 368
A Sources and Further Reading 371
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