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SAP ABAP - A Brief Introduction to Reports and Module Pool Programming
Getting Started: SAP-ABAP
Just a few steps ahead before we get our hands
dirty. It’s necessary to know the concept and other technical related things in
ABAP.
ABAP stands for Advanced Business Application Programming.
It’s a programming language
similar to COBAL and the programs we do will not be stored as a separate
external file like JAVA/C++ programs. All ABAP programs reside inside the SAP database.
As
in other programming languages, an ABAP program is either an executable unit or
a library, which provides reusable code to other programs and is not
independently executable.
ABAP
distinguishes two types of executable programs:
·
Reports ( Can be
executed directly )
·
Module pools (
They can be executed only via a ‘TRANSACTION CODE’ )
REPORTS:
Example:
You have created
a report program which gives the employee id of all the employees in your
company filtered by some parameter (take department code as parameter).so
when you execute the program it will ask for department code and gives the
result.
Here is the
example of the output, how it would look like.
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MODULE POOL:
Module pools are used to get data from the user and
store in the SAP database as well as to display them
from the database. They contain user defined screens designed using screen
painter. (Remember whenever we create screens in module pool program we have to
name them in numbers, and so we should not name our screens as ‘1000’ because
its SAP’s standard screen is ‘1000’, which it uses in report
programming and selection screens. Each screen has its own flow logic, which is
divided into a "PBO" (Process before Output) and "PAI"
(Process after Input) section. The term “dynpro” (dynamic program) refers to
the combination of the screen and its flow logic.
After all your
programming you can’t directly execute a module pool program, you have to
create a ‘TRANSACTION CODE’.
What is a transaction code?
Transaction
code is a short cut key attached to a screen. It should have only numbers and
characters (ztcode or zt42).for example if you create a transaction code for
your program, and enter the transaction code the program will be executed and
the corresponding screen will be called.
To
make it clear and easier lets have an example,
Example:
<don’t worry about the programming
logic, just try to understand this example, we shall see the programming
logic later>
You have created
a program that first requires a validation (i.e. you have to enter your
user_name and password) and then you will be redirected to your screen where
you will have all the details of you salary, expense and all.
(to make get the
point)
So, here we have
to create two screens,
Assume Screen no.
2000 for validating the user_name and password.
Screen no. 2001
for details of salary, expense.
Now create a
transaction code, eg; zuser01
Now, when you
enter the transaction code this the magic that happens, J
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So, from this you
will have clear that PBO Executes before the screen and PAI loads after
receiving an input from the user.
So we will have a
command like this in PAI.
**********************************************
PAI of screen
2000.
When ‘SUBMIT’ <when submit button
is clicked>
Call screen 2001. <the next screen is called>
**********************************************
The next PBO of
screen 2001 loads and the screen will be displayed
<remember this
is just for you to understand module pool program and the events (PAI &
PBO) in them, and programming concepts will be explained later>
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OK, now come back
to the point so far we have seen executable programs in SAP ABAP. Now we shall
have a little explanation for non-executable programs.
Include modules: An INCLUDE module
gets included at generation time into the calling unit; it is often used to
subdivide very large programs.
Example:
INCLUDE zemployee.
<here zemployee is the include, when the compiler comes here, it
executes all the commands inside zemployee>
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Subroutine pools: Subroutine pools contain blocks of code enclosed by FORM /ENDFORM
statements and invoked with PERFORM.
Example:
PERFORM zemployee.
When the compiler comes into the above line, the commands or programs
inside the subroutine zemployee will be executed <i.e. the commands within
FORM and ENDFORM of the subroutine name, here ‘zemployee’>
FORM zemployee
ENDFORM
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Function groups: Function groups are libraries of
self-contained function modules enclosed
by FUNCTION / END FUNCTION and invoked with CALL FUNCTION.
Object classes and
Interfaces: Object
classes and interfaces are similar to Java classes and interfaces; the first
define a set of methods and attributes, the second contain
"empty" method definitions, for which any class implementing the interface
must provide explicit code.
Type pools: Type pools define collections of data
types and constants.
<for the last three, giving
examples will make you confuse, when we get our hands dirty we shall have a
clear look on those types>
Introduction to SAP
The big picture: SAP AG
Before reading this i personally recommend to read my previous blog Introduction to ERP
Introduction to SAP – The Company:
SAP AG simply means SAP Inc.
SAP AG is a German multinational software corporation, founded in 1972 by 5 IBM employees (wellenreuther, Hopp, Hector, plattner and Tschira). SAP makes enterprise software to manage business operations and customer relations. SAP is headquartered in Germany and regional offices all around the world.
The first releases, called R1 and R2, were mainframe-only applications. SAP started with a set of financial applications and then added logistics, manufacturing, and HR. In the 1980s, they moved to a true 3-tiered client-server solution and by the early 1990s, R/3 was released to the market.
<We shall see about ‘R/3’ later in SAP-software>
SAP system comprises a variety of modules which fulfils all business needs.
(Sources: Wikipedia 
lol)
lol)
Introduction to SAP – The Software:
mySAP is not a single product but is a suite of products from SAP including SAP R/3.
Other products in the mySAP product suite includes,
- SRM (Supplier Relationship Management),
- CRM (Customer Relationship Management),
- PLM (Product Lifecycle Management),
- SCM (Supply Chain Management)
SAP R/3 was officially launched on 6 July 1992. It was renamed SAP ERP and later again renamed ECC (ERP Central Component).
In 2000, SAP renamed their solution mySAP and released the latest version of SAP, ‘ECC’ and the most recent release is ECC 6.0. (ERP Central Computing)
<Heard rumours about ECC 7.0 don’t know whether its true>
SAP ECC 6.0 includes many modules such as HR, Finance, MM covering all enterprise Functions.
SAP's current release strategy is to provide Enhancement Packs with additional functionality instead of releasing new versions of the software.
SAP's Enhancement Pack strategy eliminates major upgrades and allows customers to choose which enhancements to apply to their systems.
SAP NET VIEWER:
SAP first announced NetWeaver in 2003. It’s an open integration and application platform for all SAP applications.
As explained in “The History of SAP” on SAP.com, NetWeaver was an integration platform intended to enable customers to create “applications that support
end-to-end business processes no matter whether they are based on systems from SAP or other providers.”
We can consider SAP NetWeaver as a breadboard,
SAP NetWeaver provides you an application and integration platform, using which you can develop your own application on top of sap NetWeaver use sap NetWeaver for integrating or other non-sap systems  |
SAP NetWeaver Application Server
The SAP NetWeaver Application Server is the central foundation for the entire SAP software stack. It also provides a platform for other NetWeaver components.There are different installation options for SAP NetWeaver AS they are,
- SAP NetWeaver AS ABAP
- SAP NetWeaver As Java
- SAP NetWeaver As ABAP + Java
Concept of 3 Tier Architecture.
Before we discuss about 3 tier architecture, we first need to understand CLIENT and SERVER.
In Hardware: Server means Central server in a network that provides data,memory and resources for the workstations (clients)
In software: Client request’s a service and server provides the service.
3 tier architecture defines Three layers,
a. Presentation layer (SAP GUI, it provides user interface for entering and displaying data)
b. Application layer (Provides interface between presentation layer and database layer)
c. Database layer (A centralized data base that comprises all the data in the SAP system)
Whenever a user submits a request from the presentation layer, the request is processed in application layer by the dispatcher.
And when accessing Database,the application layer process the request and communicates to the data base.
(In ABAP, SQL query can be written in Open SQL to access the application data in the database,The database interface translates open SQL into Corresponding SQL statements for the specific database i.e Native SQL which makes ABAP programs to be Database-independent)
SAP supports a wide range of database,
ADABAS D
DB2/400
DB2/Common Server
DB2/MVS
INFORMIX
ORACLE
MICROSOFT SQL SERVER
(Dispatcher distributes incoming requests to the process).
Ok, now where does the distributed request from dispatcher go to process?
There are number work processes which are responsible to process the request in the application layer,
- D – Dialog work process
Responsible for the execution of dialog steps triggered by an active user.
- U – Update work process
Executes update request
- E – En queue (lock)
Administrates the lock table in the shared memory.
- B - Background work process
Executes program that run without interacting with the user.
- S – Spool work process (print)
Pass sequential data flow to printer.
Apart from work process there are additional services for internal and external communications,
- Message Server (MS)
Handles communication between the distributed dispatcher in the Application server.
- Gateway reader (GW)
Responsible for communication between SAP systems or between SAP systems and external application systems.
- Internet Communication manager (ICM)
Enables communication with SAP system using web protocol such as HTTP.
A standard SAP project system is divided into three environments, Development, Quality and Production.
The development system is where most of the implementation work takes place.
The quality system is where all the final testing is conducted before moving the transports to the production environment.
The production system is where all the daily business activities occur. It is also the client that all the end users use to perform their daily job functions.
To all company, the production system should only contain transports that have passed all the tests.
Introduction to SAP – Modules:
Here are some of the modules used in SAP (please note all modules are not mentioned here).
SAP Modules list is classified into 3 types
1) SAP Functional Modules :
People who study Functional modules are SAP Functional Consultant – They are responsible for customizing SAP as per customer demand. They talk with developers to code custom ABAP programs as per client requirements.
2) SAP Technical Modules and
They are responsible for coding ABAP/Java Programs
3) SAP New Dimensional Modules also known as SAP New Modules.
They are a combination of the Functional and Technical modules.
Functional module.
- 1. SAP FI module : FI stands for Financial Accounting.
- 2. SAP CO module : CO stands for Controlling.
- 3. SAP CRM module : CRM stands for Customer Relationship Management.
- 4. SAP HR module : HR stands for Human Resources.
- 5. SAP MM module : MM stands for Materials Management
Technical Module
- 1. SAP ABAP module : ABAP stands for Advanced Business Application Programming.
- 2. SAP Basis module : Basis also known as Basis Admin is typically the administration
- 3. SAP BI module : BI stands for Business Intelligence.
Do you know?
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Next we shall have the introduction to ABAP
