Sap Architecture

Sap System 3-tier Architecture:
     
           The image given below is 3-tier Architecture of SAP System. It contains 3 layers presentation layer, Application layer and Database layer.

          "Presentation layer" is the Front end user layer communicate with the application server to perform all the processing and which is also known as Brain of an Sap System.
           Presentation layer consist of different components for ABAP and Java that enables the communication and processing of data in Sap System.
           The communication made between the Presentation layer and Application layer is DIAG (Dynamic information and action gateway) protocol.

          "Application Layer" is the server layer which consist of the multiple instances and communicate with the database layer.
           As the above figure shows Application layer consist of Message server, Dispatcher, Work processes, user control, ABAP interpreter, SQL interpreter, Screen Interpreter and R3 buffer.

• Message server which accepts the request coming from the front end user and made a communication between dispatcher. Message server is managing the load balancing.
• Dispatcher which accepts the request coming from the message server and made a connection to the work processes in FIFO format.
• Work processes executes dialog steps in R/3 applications separately. Types of work processes are given below.

1. Dialog work process          :It is responsible for dialog process.
2. Background work process :It is responsible for background work process.
3. spool work process            :It is responsible for output requests.
4. Enqueue Work process      :It is responsible for locks
5. Update work process         :Responsible for updates.
6. Gateway work process      :It is responsible for connection between systems.

• ABAP interpreter is responsible to monitor the dispatcher queue.
• SQL interpreter is responsible to take with database.
• Screen interpreter is responsible for displaying the process of the system.
• R3buffer is responsible to store the recent transactions updated in database.   

          "Database layer" is responsible to store all the data. The database of the Sap system is kept on a separate server for performance and security reasons.