SAP ERP Architecture Models - Debabrata-Barui/SAP_ABAP_NOTE GitHub Wiki

What are SAP ERP Architecture Models?

There are three architecture models which existed in SAP ERP.

  1. R/1 : 1 - Tier Architecture
  2. R/2 : 2 - Tier Architecture
  3. R/3 : 3 - Tier Architecture Here, "R" stands for Real Time Data Processing.

R/1 : 1 - Tier Architecture

SAP R/1 is a Single Layer Architecture application in which all three components Presentation, Application and Database are merged and installed in one system/Server.

R/1 : 1 – Tier Architecture

R/2 : 2 - Tier Architecture

SAP R/2 is a Two Layer Architecture application in which all three components Presentation, Application and Database are merged and installed in two systems/Servers. In R/2, Presentation component is installed in one System/Server and Application component and Database component is installed in other system/server.

R/2 : 2 – Tier Architecture

R/3 : 3 - Tier Architecture

SAP R/3 is a Three Layer Architecture application in which all three components Presentation, Application and Database are installed in three systems/Servers. In R/3, Presentation component is installed in one System/Server and Application component is installed in other system/server Database component is installed in other system/server

R/3 : 3 - Tier Architecture

SAP R/3 Architecture in Detail

It consists of three servers.

  1. Presentation server
  2. Application server
  3. Database server

Presentation server :

It is an interface which helps user to interacrt with sap r/3 system. Note : sap gui.exe(SAP Logon) file is installed at front end which help user to interact with sap r/3 system.

Application server:

The dispatcher is an important component of application server. It monitors all the requests (tasks) in sap r/3 system. For that it maintains different work process to which it allocates the task. The work process then executes the task. All the requests that comes from presentation server are first directed to dispatcher. The dispatcher puts all the requests in dispatcher queue and then fix the requests from the dispatcher queue in fifo basis and then allocates the requests to work process. The work process executes the requests with the help of two special memory management areas such as user context and roll area.

User context: it is a special memory management area where the user settings are stored such as user authorization and the currrent program user is running etc.,

Roll area: it is a special memory management area where the system stores program information such as values for variables, dynamic memory management allocation. The different work processses are

  1. Dialogue work process
  2. Background work process
  3. Spool work process
  4. Enqueue work process
  5. Update work process
  6. Message work process
  7. Gateway work process.

Dwp : it is used to execute the task or request immediately by displaying some output. Another request can be performed from the same user or the other.

Bgwp: it is responsible for executing the abap/4 program or reports in background. It executes the abap/4 program at the pre-determined time. In response to certain events.

Swp: it is responsible for sending the data to the output devices. Eg: printer, i.e., the data to be printed present in spool.

Enqueue wp: it is responsible for the lock management system and it prevents several users to change the data, record at the same time.

Update wp: it is used to update the data to the database table.

Message wp: it acts as a mediator between two application servers which will balance the load distribution.

Gateway wp: it helps the sap r/3 system to communicate with external application (non-sap or sap system) which are remotely located with the help of tcp/ip of cpi-c (common programming interface – communication).

Work process is also called application services.

A work process consists of two software processors.

Screen processor: It executes a screen and makes the user to enter valid data on to it. If the user enters the invalid data in the fields then the screen processor will display an error message so that the user can enter the valid data.

Abap/4 processor: The screen processor gives a valid data to the abap/4 processor then the abap/4 porcesser takes these valid data and executes the Actual processing logic of abap/4 apllication during which abap/4 processor interacts with database. Interfaces in order to get the data from database tables for further process.

Database interface: It is the place where the information stored. It stores application data such as customer and transaction data and also stores customizing, configuring, historical and statistical data. In addition to this, all programs of sap and customer are stored in database. There are 3 ways to configure sap r/3 system.

  1. Central configuration
  2. 2- tier configuration
  3. 3- tier configuration In central configuration, all the three layers are installed in a single pc. In 2-tier configuration, any of the two servers are installed in one pc and the another server on another pc. In 3-tier configuration, all the three servers are installed separately on separate systems.