The document describes the architecture of an SAP system. It consists of individual systems connected to a central application server. The application server has multiple layers including a presentation layer (SAP GUI), application layer (where ABAP programs run), and database layer (where persistent data is stored). It uses work processes, a dispatcher, and shared memory to distribute requests from users to programs and return outputs. Data can be accessed using Open SQL statements which are converted to native database SQL.

2.  Individual System.
System

3.  Systems are connected to Server.
System
Ser
ver

5.  Input, allowing the users to manipulate the
system Output, allowing the system to
produce the results of user’s manipulation.
 SAP is having Graphical User interface (SAP
GUI). The SAP GUI is installed on Individual
machines which acts as presentation layer.

7.  In Application layer, ABAP programs communicate with the database
management system of the central relational database (RDBMS) and
with the presentation layer.
 ABAP applications are written in the ABAP programming language,
and run within the application layer of the SAP Web Application
Server.
 Here, application programs are executed. The application layer
contains a kernel written primarily in C/C++ that serves as a
platform for the application programs.
 The kernel of AS ABAP provides Virtual Machines for ABAP with ABAP
Objects (main programming interface of AS ABAP for business
applications), XSLT and ST (transformation languages for
transforming ABAP data to XML and vice versa), and still JavaScript
(obsolete, server-side scripting in BSPs beside ABAP).

8.  Dispatcher.
 Gateway.
 shared memory.

9.  Work Processes.
• Work processes are components that are able
to execute an application (that is, one dialog
step each).
• Each work process is linked to a memory area
containing the context of the application
being run.
• The context contains the current data for the
application program. This needs to be
available in each dialog step.

10.  Dispatcher
• The dispatcher is the link between the work
processes and the users logged onto the
ABAP application server.
• Its task is to receive requests for dialog steps
from the SAP GUI and direct them to a free
work process.
• In the same way, it directs screen output
resulting from the dialog step back to the
appropriate user.

11.  Gateway
 This is the interface for the communication
protocols of NetWeaver AS ABAP (RFC, CPI/C).
 It can communicate with other ABAP
application servers of the same NW AS, with
other SAP Systems, or with external non-SAP
systems.

12.  Shared Memory.
 All of the work processes on an ABAP
application server use a common main
memory area called shared memory to save
contexts or to buffer constant data locally.
 Memory management in the NetWeaver AS
ABAP ensures that the work processes always
address the correct context, that is the data
relevant to the current state of the program
that is running.

13.  Persistent data is held in a database.
 The database is accessed by ABAP programs
through the database interface of AS ABAP that is
subdivided into an Open SQL interface and a
native SQL interface.
 Open SQL is a subset of the Structured Query
Language (SQL) realized directly by ABAP
statements. Native SQL are database-specific SQL
instructions that are passed directly to the
database system.

14.  Open SQL:
 Open SQL consists of a set of ABAP statements that perform
operation on central database in the R/3 System.
 When a programmer writes an ABAP program with Open SQL
statements, the kernel SAP programs convert Open SQL
statements to real / native SQL statements for database in use.
So like that write once, run for all databases and even for all
operating systems.
 Open SQL contains the following keywords:
 SELECT - Reads data from database tables.
 INSERT - Adds lines to database tables.
 UPDATE - Changes the contents of lines of database tables.
 MODIFY - Inserts lines into database tables or changes the
contents of existing lines.
 DELETE - Delete lines from database tables.
 OPEN CURSOR, FETCH, CLOSE CURSOR - Reads lines of
database tables using the cursor.

16. Develop
ment
Testing Production

17. Technical Modules
 SAP-ABAP
 SAP-BASIS
 SAP-WebDynPro
Functional Modules
 SAP-SD
 SAP-MM
 SAP-CO
 SAP-FI
 SAP-BI