SAP ABAP Overview
What is ABAP?
ABAP could also be a compiled 4th generation
programming language (4GL). The term ‘4th generation language’ means ABAP is
human-readable, easy to use, and powerful. The ABAP acronym stands for Advanced
Business Application Programming. All ABAP programs and compiled code exist in
an SAP system. Contrary to programming languages like Java, you can't execute
an ABAP program outside of SAP. SAP created ABAP for the requirements of
enhancing and increasing the functionality of an SAP system.
ABAP Code is written using tools within the ABAP
Workbench (transaction SE80.) The Workbench could also be a comprehensive suite
of programs used for developing ABAP code. The Workbench is simply available
inside an SAP system. Developers can access specific tools found within the
Workbench through transaction codes. as an example, transaction SE38 is for
the creation and maintenance of reports. Transaction SE24 is for the creation
and maintenance of classes and interfaces.
What
is ABAP used for?
SAP customers employ ABAP programmers to extend the
functionality of their SAP system to satisfy specific business needs. The
acronym WRICEF explains the sorts of objects developers create in SAP. WRICEF
stands for: Workflows, Reports, Interfaces, Conversions, Enhancements and
Forms.
ABAP developers leverage their skills and knowledge
with SAP to form custom objects in an SAP system. as an example, an ABAP
consultant might be hired to write down down custom reports that are not
available in an out-of-the-box SAP system. Most companies will use a minimum of
some custom ABAP code to vary how their SAP system behaves. It’s not uncommon
for companies that rely heavily on custom ABAP to possess completely
transformed their SAP system over time.
SAP provides many frameworks through which customers
can enhance SAP-standard code. These include user exits, business add-ins
(BAdIs), business APIs (BAPIs) and enhancement spots. Customers even have the
selection of modifying SAP-standard code directly (although this is often very bad practice). Alternatively, an ABAPer might make a z-copy of
SAP-standard code and modify it to satisfy the company’s requirements.
How
do ABAP programs work?
ABAP could also be a compiled language. The role of
the compiler is two-fold. First, the compiler could also be a gatekeeper: it
submits ABAP programs to A battery of tests to form sure the code is as
‘correct’ and as safe as possible. As an example, it’s the compiler’s job to
issue an error if a developer’s code isn't syntactically correct. Second, the
compiler translates the human-readable ABAP code into optimized byte code.
Byte code could also be a low-level kind of code
that's understood by a computer but isn’t human-readable or easy to work with.
In SAP, the byte code generated by the compiler contains functions from the C
and C++ programming languages. Behind the scenes, the ABAP runtime environment
coordinates with the SAP kernel to execute functions written in C and C++.
These functions do the particular work described by the ABAP program.
When a user executes a program in SAP the
corresponding byte code is loaded into the ABAP runtime environment and
executed. ABAP programs can't be executed outside of an ABAP runtime
environment. The ABAP runtime environment exists inside an ABAP Application
Server.
Where
are ABAP programs stored?
ABAP code is stored in database tables within an SAP
system. Code is stored in two ways:
1. Human-readable ASCII document which can be
displayed or modified using the ABAP workbench tools. A compressed version of
this code is stored in table REPORT. as an example, if a developer writes
code in transaction SE38 and saves it, that code would be stored in a table
REPORT.
2. Non-human-readable byte code that's generated by
the ABAP compiler when a developer activates their code. This byte code is
executed by the ABAP runtime environment. ABAP byte code is stored in a table
RELOAD.
How
is ABAP code executed?
When an ABAP program is executed by the user, the
corresponding byte code is loaded into the Program Execution Area (PXA). The
ABAP runtime environment then interprets the byte code and calls the suitable C
functions behind the scenes.
ABAP Features :
Object-Oriented ABAP is mentioned as ABAP Objects
and is out there as of release 4.6. SAP has released official guidelines for
implementing ABAP Objects in the proper way. While ABAP Objects shares many
similarities to languages like Java and C++, there are several notable differences.
[X] ABAP Objects doesn't support destructors. SAP
can implement a special quite destructor that calls a function module from the
C programming language. this is often for internal use only and not
available to SAP customers. For everything else, SAP employs a garbage man
behind the scenes to handle memory management.
[X] ABAP Objects doesn't allow method overloading.
this means that you simply simply cannot have two methods within the same class
with an equivalent name and visibility, but different method signatures.
[X] ABAP Objects doesn't allow multi-class
inheritance. An ABAP class can inherit functionality from exactly one
superclass. A superclass can have quite one subclass. A superclass is often
the subclass of another superclass and so-on.
How
ABAP Gets Things Done
ABAP could also be a structured language. ABAP code
relies on control-flow statements (IF/THEN/ELSE) and repetition statements
(LOOP, WHILE, DO). The intention of structured languages is to form code more
readable while also being easier to develop and maintain. This successively
reduces the costs associated with creating and maintaining custom code over
time.
ABAP is a crucial language. The overarching goal of
an ABAP program is to tell the SAP system what to undertake, not
necessarily the thanks to appearing the hay. The statements in an ABAP program
are used to change a program’s state. How the system executes the underlying
byte code generated by the compiler is that the domain of the ABAP runtime
environment and thus the SAP kernel.
Typing Discipline — Describing How The Compiler
Enforces Rules
Typing disciplines describe how the compiler treats
data declared and utilized during a programming language. Strongly typed
languages have strict rules that are enforced when the code is being compiled.
Weakly typed languages have looser rules and will produce unpredictable
results.
ABAP could also be a strongly typed language. this
means that there are strict rules governing what's allowed in ABAP and other
people's rules are enforced by the compiler, not the ABAP runtime environment.
This puts the onus of writing correct code on the developer.
The ABAP compiler uses static type checking on
program ASCII document before generating byte code. Static typing requires that
variables be clearly defined at compile time. The advantage of static typing is
that errors associated with program variables are caught by the compiler before
the program are often executed.
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