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In the R/3 System, there are various types of ABAP program. The program type determines the
basic technical attributes of the program, and you must set it when you create it. The main difference between the different program types is the way in which the runtime environment calls its processing blocks. When you run an application program, you must call at least the first processing block from outside the program, that is, from the runtime environment. This processing block can then either call further processing blocks or return control to the runtime environment. When you start an ABAP program, the runtime environment starts a processor (dependent on the program type), which calls the first ABAP processing block. An ABAP program can be started either by the user or by the system (for example, in background processing), or through an external interface (for example, Remote Function Call). There are two ways of allowing users to execute programs - either by entering the program name or by entering a transaction code. You can assign a transaction code to any program. Users can then start that program by entering the code in the command field. Transaction codes are also usually linked to a menu path within the R/3 System.
The following program types are relevant to application programming:
Type 1 :
Type 1 programs have the important characteristic that they do not have to be controlled using
user-defined screens. Instead, they are controlled by the runtime environment, which calls a series of processing blocks (and selection screens and lists where necessary) in a fixed sequence. User actions on screens can then trigger further processing blocks. You can start a type 1 program and the corresponding processor in the runtime environment using the SUBMIT statement in another ABAP program. There are also various ways of starting a type1 program by entering its program name. This is why we refer to type 1 programs as executable programs.
When you run a type 1 program, a series of processors run in a particular order in the runtime environment. The process flow allows the user to enter selection parameters on a selection screen. The data is them selected from the database and processed. Finally, an output list is displayed. At no stage does the programmer have to define his or her own screens. The runtime
environment also allows you to work with a logical database. A logical database is a special ABAP program which combines the contents of certain database tables. The flow of a type 1 program is oriented towards reporting, whose main tasks are to read data from the database, process it, and display the results. This is why executable programs (type 1) in the R/3 System are often referred to as reports, and why running an executable program is often called reporting. Since it is not compulsory to define event blocks, you can yourself determine the events to which your ABAP program should react. Furthermore, you can call your own screens or processing blocks at any time, leaving the prescribed program flow. You can use this, for example, to present data in a table on a dialog screen instead of in a list. The simplest executable program (report) contains only one processing block (START-OF-SELECTION). Executable programs do not require any user dialog. You can fill the selection screen using a variant and output data directly to the spool system instead of to a list. This makes executable programs (reports) the means of background processing in the R/3 System. You can also assign a transaction code to an executable program. Users can then start it using the transaction code and not the program name. The reporting-oriented runtime environment is also called when you run a report using a transaction code. This kind of transaction is called a report transaction. It is appropriate to use executable programs (reports) when the flow of your program corresponds either wholly or in part to the pre-defined flow of the runtime environment. Until Release 4.5A, the only way to use a logical database was to use an executable program. However, from Release 4.5A, it is also possible to call logical databases on their own.
Type M : The most important technical attribute of a type M program is that it can only be controlled using screen flow logic. You must start them using a transaction code, whcih is linked to the program and one of its screens (initial screen). Another feature of these programs is that you must define your own screens in the Screen Painter (although the intial screen can be a selection screen). When you start a program using a transaction code, the runtime environment starts a processor that calls the initial screen. This then calls a dialog module in the corresponding ABAP program. The remainder of the program flow can take any form. For example, the dialog module can: return control to the screen, after which, the processing passes to a subsequent screen. Each screen has a following screen, set either statically or dynamically. call other sequences of screens, selection screens or lists, from which further processing blocks in the ABAP program are started. call other processing blocks itself, either internally or externally. call other application programs using CALL TRANSACTION (type M program) or SUBMIT (type 1 program). ABAP programs with type M contain the dialog modules belonging to the various screens. They are therefore known as module pools. It is appropriate to use module pools when you write dialog-oriented programs using a large number of screens whose flow logic largely determines the program flow.
Type F : Type F programs are containers for function modules, and cannot be started using a transaction code or by entering their name directly. Function modules are special procedures that you can call from other ABAP programs. Type F programs are known as function groups. Function modules may only be programmed in function groups. The Function Builder is a tool in the ABAP Workbench that you can use to create function groups and function modules. Apart from function modules, function groups can contain global data declarations and subroutines. These are visible to all function modules in the group. They can also contain event blocks for screens in function modules.
Type K : You cannot start type K programs using a transaction code or by entering the program name. They are containers for global classes in ABAP Objects . Type K programs are known as class definitions. The Class Builder is a tool in the ABAP Workbench that you can use to create
class definitions.
Type J : You cannot start type J programs using a transaction code or by entering the program name. They are containers for global interface in ABAP Objects . Type J programs are known as
interface definitions. Like class definitions, you create interface definitions in the Class Builder.
Type S : You cannot start a type S program using a transaction code or by entering the program name. Instead, they are containers for subroutines, which you can call externally from other ABAP programs. Type S programs are known as subroutine pools. They cannot contain screens.
Type I: Type I programs - called includes - are a means of dividing up program code into smaller, more manageable units. You can insert the coding of an include program at any point in another ABAP program using the INCLUDE statement. There is no technical relationship between include programs and processing blocks. Includes are more suitable for logical programming units, such as data declarations, or sets of similar processing blocks. The ABAP Workbench has a mechanism for automatically dividing up module pools and function groups into include programs.
basic technical attributes of the program, and you must set it when you create it. The main difference between the different program types is the way in which the runtime environment calls its processing blocks. When you run an application program, you must call at least the first processing block from outside the program, that is, from the runtime environment. This processing block can then either call further processing blocks or return control to the runtime environment. When you start an ABAP program, the runtime environment starts a processor (dependent on the program type), which calls the first ABAP processing block. An ABAP program can be started either by the user or by the system (for example, in background processing), or through an external interface (for example, Remote Function Call). There are two ways of allowing users to execute programs - either by entering the program name or by entering a transaction code. You can assign a transaction code to any program. Users can then start that program by entering the code in the command field. Transaction codes are also usually linked to a menu path within the R/3 System.
The following program types are relevant to application programming:
Type 1 :
Type 1 programs have the important characteristic that they do not have to be controlled using
user-defined screens. Instead, they are controlled by the runtime environment, which calls a series of processing blocks (and selection screens and lists where necessary) in a fixed sequence. User actions on screens can then trigger further processing blocks. You can start a type 1 program and the corresponding processor in the runtime environment using the SUBMIT statement in another ABAP program. There are also various ways of starting a type1 program by entering its program name. This is why we refer to type 1 programs as executable programs.
When you run a type 1 program, a series of processors run in a particular order in the runtime environment. The process flow allows the user to enter selection parameters on a selection screen. The data is them selected from the database and processed. Finally, an output list is displayed. At no stage does the programmer have to define his or her own screens. The runtime
environment also allows you to work with a logical database. A logical database is a special ABAP program which combines the contents of certain database tables. The flow of a type 1 program is oriented towards reporting, whose main tasks are to read data from the database, process it, and display the results. This is why executable programs (type 1) in the R/3 System are often referred to as reports, and why running an executable program is often called reporting. Since it is not compulsory to define event blocks, you can yourself determine the events to which your ABAP program should react. Furthermore, you can call your own screens or processing blocks at any time, leaving the prescribed program flow. You can use this, for example, to present data in a table on a dialog screen instead of in a list. The simplest executable program (report) contains only one processing block (START-OF-SELECTION). Executable programs do not require any user dialog. You can fill the selection screen using a variant and output data directly to the spool system instead of to a list. This makes executable programs (reports) the means of background processing in the R/3 System. You can also assign a transaction code to an executable program. Users can then start it using the transaction code and not the program name. The reporting-oriented runtime environment is also called when you run a report using a transaction code. This kind of transaction is called a report transaction. It is appropriate to use executable programs (reports) when the flow of your program corresponds either wholly or in part to the pre-defined flow of the runtime environment. Until Release 4.5A, the only way to use a logical database was to use an executable program. However, from Release 4.5A, it is also possible to call logical databases on their own.
Type M : The most important technical attribute of a type M program is that it can only be controlled using screen flow logic. You must start them using a transaction code, whcih is linked to the program and one of its screens (initial screen). Another feature of these programs is that you must define your own screens in the Screen Painter (although the intial screen can be a selection screen). When you start a program using a transaction code, the runtime environment starts a processor that calls the initial screen. This then calls a dialog module in the corresponding ABAP program. The remainder of the program flow can take any form. For example, the dialog module can: return control to the screen, after which, the processing passes to a subsequent screen. Each screen has a following screen, set either statically or dynamically. call other sequences of screens, selection screens or lists, from which further processing blocks in the ABAP program are started. call other processing blocks itself, either internally or externally. call other application programs using CALL TRANSACTION (type M program) or SUBMIT (type 1 program). ABAP programs with type M contain the dialog modules belonging to the various screens. They are therefore known as module pools. It is appropriate to use module pools when you write dialog-oriented programs using a large number of screens whose flow logic largely determines the program flow.
Type F : Type F programs are containers for function modules, and cannot be started using a transaction code or by entering their name directly. Function modules are special procedures that you can call from other ABAP programs. Type F programs are known as function groups. Function modules may only be programmed in function groups. The Function Builder is a tool in the ABAP Workbench that you can use to create function groups and function modules. Apart from function modules, function groups can contain global data declarations and subroutines. These are visible to all function modules in the group. They can also contain event blocks for screens in function modules.
Type K : You cannot start type K programs using a transaction code or by entering the program name. They are containers for global classes in ABAP Objects . Type K programs are known as class definitions. The Class Builder is a tool in the ABAP Workbench that you can use to create
class definitions.
Type J : You cannot start type J programs using a transaction code or by entering the program name. They are containers for global interface in ABAP Objects . Type J programs are known as
interface definitions. Like class definitions, you create interface definitions in the Class Builder.
Type S : You cannot start a type S program using a transaction code or by entering the program name. Instead, they are containers for subroutines, which you can call externally from other ABAP programs. Type S programs are known as subroutine pools. They cannot contain screens.
Type I: Type I programs - called includes - are a means of dividing up program code into smaller, more manageable units. You can insert the coding of an include program at any point in another ABAP program using the INCLUDE statement. There is no technical relationship between include programs and processing blocks. Includes are more suitable for logical programming units, such as data declarations, or sets of similar processing blocks. The ABAP Workbench has a mechanism for automatically dividing up module pools and function groups into include programs.
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