SAP R3 Architecture - Sapgui, Application server and Database server

SAP is having a 3 tier (R3) client-server architecture, which consists of :

• Presentation Server
• Application  Server
• Database Server

Presentation Server:      Actually presentation server is  a program named sapgui.exe, which is usually installed on user's workstation.

This program is responsible for sending all the user inputs to the application server and for retrieving the data from the application server and also it displays the screens.

To start it, user should double click on it. 

Sap Logon

Application Server: Application Server is responsible for interpreting the ABAP/4 programs. It consists of many executable programs which gets started automatically whenever the application server gets started.

Each application server has a profile that specifies its characteristics when it start ups and when it is running.

An Application server profile mainly contains:

• Number and type of each process.
• Amount of memory used for each process.
• Length of time a user is inactive before being automatically logged off.

Database Server:   The database server consists of several executable files to process the requests from Application server. After processing the requests these requests are passed to RDBMS (Relational Database Management System). RDBMS will send the data back to the database server and database server will forward this data to the Application server. This Application server inturn passes the data to the ABAP/4 program.