SAP R/3 Architecture

                SAP R/3 is one of the main product of SAP,where R stands for Real Time and the number 3 relates to three tier application architecture(Data base,Application Server and Client).

                Most of the business in today's world runs on SAP R/3 system.About 80% of the companies implemented this software.SAP R/3 Software has been developed using ABAP/4 as a programming language.

                SAP based the architecture of R/3 on a three-tier client/server model.

1. Presentation Server
2. Application Server
3. Database Server

 

Presentation Server:

• The presentation server is actually a program named sapgui.exe. It is usually installed on a user’s workstation.


• This is commonly known as the SAPGUI, or the user interface.


• The interface accepts input from the user in the form of keystrokes, mouse-clicks, and function keys, and sends these requests to the application server to be processed.


• The application server sends the results back to the SAPGUI which then formats the output for display to the user.


• The output from these transactions appears as output fields, reports, tables and spread sheets.

Application Server:

• An application server is a set of executables that collectively interpret the ABAP/4 programs and manage the input and output for them.


• When an application server is started, these executables all start at the same time. When an application server is stopped, they all shut down together.


• Each application server has a profile that specifies its characteristics when it starts up and while it is running. For example, an application sever profile specifies:


1. Number of processes and their types
2. Amount of memory each process may use
3. Length of time a user is inactive before being automatically logged off


• If your ABAP/4 program requests information from the database, the application server will format the request and send it to the database server.

Database Server:

• The database server is a set of executable that accept database requests from the application server.


• These requests are passed on to the RDBMS (Relation Database Management System).


• The RDBMS sends the data back to the database server, which then passes the information back to the application server.


• The application server in turn passes that information to your ABAP/4 program.


• There is usually a separate computer dedicated to house the database server, and the RDBMS may run on that computer also, or may be installed on its own computer.


• In a three-tier client/server configuration, the presentation servers, applications servers, and database server all run on separate machines. This is the most common configuration for large systems, and is common in production.


• In the distribution presentation configuration, the application and database servers are combined on one computer and the presentation servers run separately. This is used for smaller systems, and is often seen on a development system.


• In the two-tier client/server configuration, the presentation and application servers are combined and the database server is separate. This configuration is used in conjunction with other application servers. It is used for a batch server when the batch is segregated from the online servers. A SAPGUI is installed on it to provide local control.

Configuring the Servers:

• In a three-tier client/server configuration, the presentation servers, applications servers, and database server all run on separate machines. This is the most common configuration for large systems, and is common in production.


• In the distribution presentation configuration, the application and database servers are combined on one computer and the presentation servers run separately. This is used for smaller systems, and is often seen on a development system.


• In the two-tier client/server configuration, the presentation and application servers are combined and the database server is separate. This configuration is used in conjunction with other application servers. It is used for a batch server when the batch is segregated from the online servers. A SAPGUI is installed on it to provide local control.