SAP architecture constitutes a distribution system that works in a common environment provided by the Netweaver. The three tier architecture of SAP Web Application Server includes presentation layer, application layer and the database layer.
In this layer the user is provided with an interface through which the interaction is carried out with different applications. The Graphical User Interface executes logic applications and utilizes other interfaces as well.
The presentation server is programmed as sapgui.exe and installed in the workstation of the user. By double clicking the icon on the desktop, the user chooses a menu path and a list of R/3 menus are displayed by the presentation server in a window, known as SAPGUI or the user interface. Inputs are given through mouse-clicks and key board to be processed by the application server and the results are displayed as outputs to the user after being formatted by the SAPGUI.
A number of executables constitutes this layer which interprets the ABAP/4 programs collectively and the inputs and outputs are managed for the application server. When the application server starts running, these executables start functioning and stops when the application server doesn't run. Every application server is assigned specific profile in the start up and the running process that can be characterized as
1. Total number of processes and their types
2. Usage of memory by the processes
3. Period of time taken by the processes
The application server interprets and runs the ABAP/4 programs in the server itself. But the ABAP/4 is able to start the executable programs in the presentation server but cannot execute in it. For proper execution requests for information are sent to the database by ABAP/4 via the application server to the database server.
The Database Server also constitutes a set of executables receiving data requests from the application server. The requests are sent to RDBMS (Relation Data Base Management Systems) which after processing are returned to the database server. From the database server the information reaches the application server finally passing to the ABAP/4 program.
Multi Layered Architecture can also be created in a distributed architecture, the work being distributed through a number of layers. This facilitates scalability as the load of work gets distributed in many layers. Due to the active participation and communication of different servers, the functioning of the layers can be spread out to different servers. This facility renders flexibility of running in different hardware or OS environments.
Internet Enabled Architecture is the latest version of SAP architecture where the SAP Basis is provided with a web server that can access internet. Utilizing the Internet Communication Management, the SAP web server helps in effective communication to the internet, both as a client and a server.