SAP delivers a broad range of business functions within its R/3 application suite. You may find that the standard applications do not offer some of the functionality you need. The R/3 enchancement concept allows you to add your own functionality to SAP's standard business applications.
SAP creates customer exits for specific programs, screens and menus within standard R/3 applications. These exits do not contain any functionality. Instead, the customer exits act as hooks. You can hang your own add-on functionality onto these hooks.
Purpose of the Enhancement Concept
With the ABAP/4 Development Workbench, SAP's client-server development environment, you can create add-ons or entire applications. Before the enhancement concept existed, customers who wanted to add their own specific functions to SAP software had to modify the standard SAP programs. Modifying SAP's software holds at least two dangers:
1.Modifying standard code can lead to errors
When a customer changes the source code of a standard program, these changes can have unwanted results within other parts of the application. Once a customer has begun 'reconstructing' a standard program, SAP can no longer guarantee that this customer's system will run without serious errors.
2.Modifications mean more work during software upgrades
Customers of standard software packages often want to take advantage of software upgrades or new releases. Customers who have modified the software of their current release must save these modifications and reenter them into the new software after each upgrade or release change. Depending on the number and scope of modifications, this reentry process may make it difficult or even impossible to take advantage of new software releases.
The enhancement concept offers a better alternative to the problem-ridden modification approach.
Reason for Using Exits
If you want to extend the functionality of your R/3 System, you should take advantage of the exits available within the standard R/3 applications. There are two main reasons why you should use exits rather than modifying SAP software. Add-ons that are attached to exits have the advantage that they:
1.Do not affect standard SAP source codeWhen you add new functionality to your R/3 System using SAP's exits, you do not change the source code of standard SAP programs. The code and screens you create are encapsulated as separate objects. These customer objects are linked to standard applications, but they exist apart from SAP's standard software package.
2.Do not affect software upgradesWhen you add new functions using SAP's exits, the objects you develop are customer objects. Customer objects adhere to strict naming conventions. When the time comes to upgrade a software release, the special names of customer objects ensure that they will not be affected by either changes or additions within the standard software package. As a result, you do not need to save and then reenter add-ons attached to exits.
Customer exits are not available for all programs and screens within the R/3 standard applications. You can only use exits if they already exist within the SAP R/3 System. Locating Applications that Have Exits explains how to find applications with predefined exits.
If no user exit is available in an area where you want to add your own functionality, you can request that SAP develop an exit. You can make this request via the Online Service System (OSS).
Types of Exits
There are four basic types of customer exits. Each of these exits is a hook that you can hang your add-ons onto.
Menu exitsAdd items to the pulldown menus in standard R/3 applications. You can use these menu items, for example, to call up your own screens or to trigger entire add-on applications.
SAP creates menu exits by defining special menu items in the Menu Painter. These special entries have function codes that begin with + (plus sign). You specify the menu item's text when activating the item within an add-on project.
Screen exitsAdd fields to the screens within R/3 applications. SAP creates screen exits by placing special subscreen areas within a standard R/3 screen and calling a customer subscreen from within the standard dynpro's flow logic.
Function module exits Add functionality to R/3 applications. Function module exits play a role in both menu and screen exits. When you add a new menu item to a standard pulldown menu, for example, you can use a function module exits to define the actions that should take place once your menu is activated. Function module exits also control the data flow between standard programs and the fields created within dynpro exits.
SAP application developers create function exits by preparing calls to customer functions within standard R/3 programs. These calls have the following syntax: CALL CUSTOMER-FUNCTION '001'.
Keyword exits Add documentation to the data elements of key words defined in the ABAP/4 Dictionary. The system displays this documentation whenever a user presses F1 to get online help for a screen field.
Unlike the other exits listed above, documentation exits do not require that SAP make any special preparations.
Creating an Add-on Project
To take advantage of the exits available within standard R/3 applications, you need to create an add-on project. This project lets you organize the enhancement packages and exits you want to use. The add-on project also allows you to hang add-on functionality onto the exit hooks contained with SAP enhancements.
Managing an Add-on Project
An add-on project contains a series of exits and the add-ons, such as menu entries or function modules, that you develop to hook onto these exits. To create an add-on project from within the ABAP/4 Development Workbench menu, choose Utilities ® Enhancements ® Project management.
Before you begin defining a project, you need to decide which application, application component, or specific standard transaction you would like to add your own functionality to. Give your project a name that indicates the type of functions it contains or shows which transactions are affected. It might be useful to agree upon a company-wide naming convention for enhancement projects.
There are two factors you need to keep in mind when you create an add-on project. First, you can include an SAP enhancement package and the customer exits it contains in one project only. The same SAP enhancement may not appear in two different customer projects.
Second, in order to make your add-ons, such as menu items or screen fields, appear in standard R/3 applications, you must activate your add-on project. When you activate a project, all of the add-ons created within this project are turned on. For this reason, you should ensure that the exits you include in your project contain functions that can be activated simultaneously. It is not possible to activate specific exits only.
After you have specified the name of your new project, proceed as follows:
1. Choose Create.
2. Describe the nature of the project by providing a short descriptive text.
3. Choose the SAVE icon.
The system prompts you to assign a change task. This assignment allows you to transport the project and its components into a productive system once you have completed it.
4. Specify which SAP enhancements packages you want to include in your project by choosing SAP enhancements.
5. Enter the names of all the SAP enhancements in the spaces provided.
You should choose enhancements packages which logically belong together. If you are planning to use several enhancements that deal with Materials Management modules, for example, you can include each of these enhancements in the same project. If you are working on enhancements that deal with different applications, or if the enhancements are not logically related, you should include these enhancements in separate projects.
Once you have identified the SAP enhancements to include in your project, you can begin adding your own functionality to the exits offered in the enhancements. To display the individual components of the SAP enhancements, return to the main screen of the Project Management transaction and choose Enhancement components. The system shows you all of the exits included in each of the enhancements assigned to your project.
To take advantage of the exits available within standard R/3 applications, you need to create an add-on project. This project lets you organize the enhancement packages and exits you want to use. The add-on project also allows you to hang add-on functionality onto the exit hooks contained with SAP enhancements.
Managing an Add-on Project
An add-on project contains a series of exits and the add-ons, such as menu entries or function modules, that you develop to hook onto these exits. To create an add-on project from within the ABAP/4 Development Workbench menu, choose Utilities ® Enhancements ® Project management.
Before you begin defining a project, you need to decide which application, application component, or specific standard transaction you would like to add your own functionality to. Give your project a name that indicates the type of functions it contains or shows which transactions are affected. It might be useful to agree upon a company-wide naming convention for enhancement projects.
There are two factors you need to keep in mind when you create an add-on project. First, you can include an SAP enhancement package and the customer exits it contains in one project only. The same SAP enhancement may not appear in two different customer projects.
Second, in order to make your add-ons, such as menu items or screen fields, appear in standard R/3 applications, you must activate your add-on project. When you activate a project, all of the add-ons created within this project are turned on. For this reason, you should ensure that the exits you include in your project contain functions that can be activated simultaneously. It is not possible to activate specific exits only.
After you have specified the name of your new project, proceed as follows:
1. Choose Create.
2. Describe the nature of the project by providing a short descriptive text.
3. Choose the SAVE icon.
The system prompts you to assign a change task. This assignment allows you to transport the project and its components into a productive system once you have completed it.
4. Specify which SAP enhancements packages you want to include in your project by choosing SAP enhancements.
5. Enter the names of all the SAP enhancements in the spaces provided.
You should choose enhancements packages which logically belong together. If you are planning to use several enhancements that deal with Materials Management modules, for example, you can include each of these enhancements in the same project. If you are working on enhancements that deal with different applications, or if the enhancements are not logically related, you should include these enhancements in separate projects.
Once you have identified the SAP enhancements to include in your project, you can begin adding your own functionality to the exits offered in the enhancements. To display the individual components of the SAP enhancements, return to the main screen of the Project Management transaction and choose Enhancement components. The system shows you all of the exits included in each of the enhancements assigned to your project.
Activating and Deactivating a Project
After you have attached all add-on functionality to the exits in your project, you need to activate the project. Activating a project turns on all your add-ons. You also need to activate your project after you have transported it from a development system into a productive system.
When you activate your project, the system turns on all the add-ons contained within the project. You cannot activate certain add-ons separately. The activate an add-on project, proceed as follows:
1. Enter the Project Management transaction.
2. Choose Activate project.
The system confirms that the project was activated.
You can now call up a standard SAP transaction that contains an exit you used in your add-on project. Your add-on functionally should appear.
If you need to make changes to any of your add-ons, you must first deactivate the project that contains that add-on. Deactivating a project turns off all of that project's add-ons. To deactivate an add-on project, proceed as follows:
1. Enter the Project Management transaction.
2. Choose Deactivate project.
The system confirms that the project was deactivated.
Once the project is turned off, you can make changes to the project's add-ons or build new functionality to hook on to the other exits in the project.
Transporting Add-on Projects
To take advantage of the exits in the R/3 System, you must create an add-on project. This project contains at least one SAP enhancement package and all the user exits assigned to this package. Your add-on project also holds the add-on functionality you create to hang onto the exit hooks.
When you first create an add-on project, you must assign the project to a change task. You also need to allocate a change task number for every add-on component you develop, such as include programs, subscreens, and menu texts. You can use the same change task number for all your project components. If your project is spread out over more than one change task, you should assign these tasks to the same transport request.
Once you have completed your project, release your change tasks. As a final step, release the transport request that contains all the change tasks for your project. The system will export your add-on project and coordinate its import into a consolidation or productive system. You must then ensure that your add-on project is active.
Using Field Exits
Field exits allow you to create your own programming logic for any data element in the Dictionary. You can use this logic to carry out checks, conversions, or business-related processing for any screen field.
The data element BBBNR identifies a company's international location number. You might want to set up your R/3 System so that all international location numbers are larger than 100. The field exit concept lets you create a special function module that contains this logic.
You assign the special function module to the data element BBBNR. You then assign the module to any programs and screens in which users can add new international location numbers. When you activate your field exit, the system automatically triggers your special routine whenever a user enters a company location number.
To create your own logic for a particular data element, proceed as follows:
1. Enter the Project management transaction by choosing Utilities ® Enhancements ® Project management from the ABAP/4 Development Workbench menu.
2. Choose Text enhancements ® Field exits.
3. Choose Field exit ® Create.
4. Enter the name of data element.
5. Choose Continue.
The system takes you into the Function Library and suggests a name for your function module (FIELD_EXIT_BBBNR). You should use this name.
6. Create the source code and, if needed, global data for your function module.
7. Activate the function module.
After you have created the processing logic for your field exit, you must assign the exit to one or more programs and screens. This assignment tells the system which screens to trigger your function module on.
If your processing logic checks naming conventions for a certain field, for example, you might want to trigger the field exit module only on screens where new data can be written to the database. If another screen allows you to display data only, then you can leave out the special function module call. To assign your field exit module to one or more screens, proceed as follows:
1. Select the field exit.
2. Choose Assign prog./screen.
3. Enter the name of the program and the screen number.
4. Choose Save.
For some fields, you might want to trigger a different processing logic on different screens. You can trigger screen-specific logic by allocating a field exit identifier when you make your screen assignments. A field exit identifier can be any number or letter. The field exit identifier tells the system to trigger the function module that has this identifier in its name.
You create a field exit for the data element BBBNR. You make the following exit and screen assignments:
Field exit Program Screen
1 SAPMI0IA 2300
2 SAPMI0IA 3450
If a user makes an entry into the BBBNR-related field in screen 2300, the system triggers the function module called FIELD_EXIT_BBBNR_1. If the user makes the same entry in screen 3450, the system triggers the function FIELD_EXIT_BBBNR_2.
After you have created one or more function modules and assigned them to programs and screens, you need to activate the field exit. Choose Field exit ® Activate. The system will trigger the processing logic in your function modules according to the screen assignments you made.