This segment from our 415 page ABAP Programming manual is being made available as a sample of our training manuals. Please contact
[email protected] if you have any SAP training needs, or visit www.ERPtips.com for more information. Written by Rehan Zaidi and John Verbestel Published by Klee Associates, Inc. Copyright Klee Associates, Inc., 2008, 2009
Unit 3 – Function Groups and Function Modules Overview of Function Groups and Function Modules The following figure describes the basic construct of a Function Group, which is a specialized program.
Although created and referenced as the function group ZMAT, the underlying program is named SAPLZMAT. The SAPL prefix defines this program as a ABAP Programming Language
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function group, and is created automatically by the Function Builder, SAP Transaction SE37. The program is organized by a series of Include programs for handling global data, and each individual function module. Function Modules are created separately, and although unique to the SAP system, they must be assigned to a Function Group.
Creating a Function Group Function groups are created using transaction SE37 (function builder). A Function Group is realized in the SAP Software system as a program, containing a logically related set of function modules. When creating function groups, realize that when a program (client) calls a function module, the function group and all its global data are instantiated and consume runtime memory until the end of the calling program (client lifetime). Do not overload your function group as it may result in effecting the performance of the calling program. Create the function group by selecting the menu path Goto Function Groups Create Group.
The following popup will request the details of the function group. Customer function groups should begin with a Z or a Y.
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After saving, the function group will be requested to be assigned to a package, then a change request for transport and control requirements.
Creating a Function Module Function modules are created using transaction SE37 (function builder). The standard SAP system has a number of predefined function modules. Function modules are best used for carrying out database updates and communicating with different SAP systems. In contrast to subroutines, function modules do not need to be defined in the source of your ABAP program. Function modules may have both input and output parameters. The input parameters can be mandatory or optional. You can also assign default values to parameters. Function modules also provide the option of exception handling, which catches errors when the function module executes. You may also test function modules from transaction SE37 before including them in your programs. Function Modules must begin with a Z_ or a Y_, and can be created as follows: 1. Enter the new function module name and click the Create button.
2. Assign the function group.
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3. Define the interface to the function module. The Attributes of the function module should be reviewed first, as it controls the behavior of the overall function module.
The processing type controls the behavior of the function module.
Normal Function Module
Remote Function Module
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Used for modularizing code and is not externally visible to other systems, but globally visible within the same SAP software system. Visible to external systems, and thus can be called via the RFC gateway.
Update Function Module
Denotes the use of the function module for Asynchronous update purposes.
The three sub-selections pertain to the database logical unit of work and when the function module is executed in the context of the update task. More information can be found under Asynchronous Update Techniques.
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The interface is based on the following:
Inbound Data to be received from the calling program
Note the commonality with subroutines, where you can pass by reference (Default) or pass by value. Optional parameters can be assigned a default value, and do not need to be provided by the calling program.
Outbound Data to be returned to the calling program
Changing Data to be received and returned using the same reference variable
Tables
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Obsolete interface for passing arrays of information. Use global table types going forward, in combination with the Changing interface. However, many delivered function modules still use the Tables interface.
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Exceptions
Exceptions, resulting in non-zero values of the system variable SYSUBRC.
Exceptions are raised using the RAISING command in the source code of the function module.
In the figure above, the exception NOCUSTOMERFOUND is declared. Function Modules now have the added capability to use exception classes. This will be described in the Introduction to Object Oriented ABAP unit. 4. Enter the source code.
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The source code will show the current interface as comment statements. Do not try to change the comment statements as it will make no difference to the interface. Note the use of the RAISE statement in the code above to trigger an exception. When the RAISE statement occurs, the program processing jumps to the ENDFUNCTION, and the control is passed back to the calling application.
Testing the Function Module The Function Builder has its own test workbench, and can be accessed using the TEST icon, the same one used in the ABAP Editor. On the main screen, select the test icon as demonstrated below.
The next screen will request the input parameters for the function module being tested.
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Click Execute or Execute in Debugging once the input fields are entered. The results are shown in the next image.
The above was a successful test, and all the return parameters can be viewed directly. It can be seen that three records were returned in the T_Salesinfo table, and that the export structure E_Cust_Detail has information contained within. If the test failed, a result would appear as the next screen demonstrates. The exception is displayed as the main result, and all other export fields are empty.
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Working with Function Groups in the Object Navigator Use the package or the function group view in the object navigator (SAP Transaction SE80 to show the function group and it's modules so that they can be edited directly from the Workbench. An example is presented below:
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Using Function Modules in ABAP Programs For including function modules that already exist in the system, simply click on the icon from the ABAP Editor while in the Change mode. The dialog box (shown in the next figure) appears:
By entering the name of the function module in the CALL FUNCTION field, and pressing Enter, the relevant function module call will be added directly in the program at the cursor.
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The following can be noted, when using the Pattern button to insert the function module call:
All interface parameters and exceptions are imported.
Optional parameters, Importing parameters, and exceptions are automatically commented out.
A basic if statement is added to handle any exceptions, and a commented out message statement.
You may then pass appropriate values to the function module to get the desired result. You must define suitable data objects that have types compatible to the parameters of the function module in question.
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