Explain the SAP R/3 ‘System Architecture

SAP R/3 is based on a 3-tier Client-Server model, represented by the:

ƒ 1.Database Layer

ƒ 2.Application Layer

ƒ 3.Presentation Layer

In a 3-tier Client server model, all the above three layers run on three different machines.

The Database Layer consists of an RDBMS (Relational Database Management System), which Accepts the database requests from the Application Layer, and sends the data back to the Application Layer, which in turn passes it on to the Presentation Layer.

The Application Layer or the server interprets the ABAP/4 programs, receiving the inputs from Them and providing the processed output to them.

The Presentation Server or ‘Presentation Layer’ is what is installed on the typical workstation of  a user. This is nothing but the SAPGUI, which when started provides the user with the interface of SAP R/3 menus. This interface accepts the inputs from the user, passes them on to the  Application Server processes the inputs and sends back the output. If database processing is Required, the Application Server sends the details to the Database Layer, receives the data, and Then processes it at the Application Layer level and sends back the output to the Presentation Layer where the SAPGUI may format the data before displaying it on the screen