What is ABAP?

ABAP (Advanced Business Application Programming) is a high level programming language created by the German software company SAP. It is currently positioned, alongside the more recently introduced Java, as the language for programming SAP's Web Application Server, part of its NetWeaver platform for building business applications. Its syntax is somewhat similar to COBOL.

History

ABAP is one of many application-specific fourth-generation languages (4GLs) first developed in the 1980s. It was originally the report language for SAP R/2, a platform that enabled large corporations to build mainframe business applications for materials management and financial and management accounting. ABAP used to be an abbreviation of Allgemeiner Berichtsaufbereitungsprozessor, the German meaning of "generic report preparation processor", but was later renamed to Advanced Business Application Programming. ABAP was one of the first languages to include the concept of Logical Databases (LDBs), which provides a high level of abstraction from the basic database level.

The ABAP programming language was originally used by developers to develop the SAP R/3 platform. It was also intended to be used by SAP customers to enhance SAP applications – customers can develop custom reports and interfaces with ABAP programming. The language is fairly easy to learn for programmers but it is not a tool for direct use by non-programmers. Good programming skills, including knowledge of relational database design and preferably also of object-oriented concepts, are required to create ABAP programs.

ABAP remains the language for creating programs for the client-server R/3 system, which SAP first released in 1992. As computer hardware evolved through the 1990s, more and more of SAP's applications and systems were written in ABAP. By 2001, all but the most basic functions were written in ABAP. In 1999, SAP released an object-oriented extension to ABAP called ABAP Objects, along with R/3 release 4.6.

SAP's most recent development platform, NetWeaver, supports both ABAP and Java.

Implementation

Where Does the ABAP Program Run?
All ABAP programs reside inside the SAP database. They are not stored in separate external files like Java or C++ programs. In the database all ABAP code exists in two forms: source code, which can be viewed and edited with the ABAP workbench, and "compiled" code ("generated" code is the more correct technical term), which is loaded and interpreted by the ABAP runtime system. Code generation happens implicitly when a unit of ABAP code is first invoked; it can also be requested explicitly, which is very useful in some situations, for example for mass regeneration of code after a release upgrade. If the source code is changed later or if one of the data objects accessed by the program has changed (e.g. fields were added to a database table), then the code is automatically regenerated.

ABAP programs run in the SAP application server, under control of the runtime system, which is part of the SAP kernel. The runtime system is responsible for processing ABAP statements, controlling the flow logic of screens and responding to events (such as a user clicking on a screen button). A key component of the ABAP runtime system is the Database Interface, which turns database-independent ABAP statements ("Open SQL") into statements understood by the underlying DBMS ("Native SQL"). The database interface handles all the communication with the relational database on behalf of ABAP programs; it also contains extra features such as buffering of frequently accessed data in the local memory of the application server.

SAP Basis

The ABAP language environment, including the syntax checking, code generation and runtime system, is part of the SAP Basis component. SAP Basis is the technological platform that supports the entire range of SAP applications, now typically implemented in the framework of the SAP Web Application Server. In that sense SAP Basis can be seen as the "operating system" on which SAP applications run. Like any operating system, SAP Basis contains both low-level services (for example memory management, database communication or servicing Web requests) and high-level tools for end users and administrators. These tools can be executables ("SAP kernel") running directly on the underlying operating system, transactions developed in ABAP, or Web-based interfaces.
SAP Basis also provides a layer of abstraction between the business applications and the operating system and database. This ensures that applications do not depend directly upon a specific server or database platform and can easily be ported from one platform to another.

SAP Basis currently runs on UNIX (AIX, HP-UX, Solaris, Linux), Microsoft Windows, IBM Series i (former iSeries, AS/400) and IBM zSeries (former S/390). Supported databases are DB2, Informix, MaxDB, Oracle and Microsoft SQL Server (support for Informix was discontinued in SAP Basis release 7.00).