SAP SYSTEM

PRESENTATION SERVERS:-

  Users can access SAP system in two ways:-

1. Through SAP GUI
2. Through Web browser

It's called front-end. Only the front-end is installed in the user's PC not the application/database servers.

Front-end takes the user's requests to database server and application servers.

Application Servers:- 

                             Application server is built to process business-logic. This workload is distributed among multiple application servers.With multiple application servers user can get the output more quickly.

Application server exists at a remote location as compared to location of the user PC.

Database Server:- 

                                      Database server stores and retrieves data as per SQL queries generated by ABAP and java applications.

Database and Application may exist on the same or different physical location.

DETAILS OF R/3 TIER

PRESENTATION SERVERS:

#presentation server is the server which directly handle the sap user(gui),

# it collect the requirement from end users and send it to the data base layer for the response of that,where data base server is the main server which have all the data information and tables, 

#application server is situated between both,presentation and database server and it provides interfacing b/w the database & presentation server.so it is called as sap r/3, but now a new concept is  introduced that is net weaver concept, in which a new layer  is introduced that is internet layer.

#SAP allows the IT supported processing of a multitude of tasks which occur in a typical company. The newer SAP ERP software differs from R/3 mainly because it is based on SAP NET WEAVER core components can be implemented in ABAP and in  JAVA and new functional areas are mostly no longer created as part of the previous ERP system, with closely interconnected constituents, but as self-contained components or even systems.

 

 APPLICATION SERVERS:

• Initializes the application server:
• Reads configuration
• Creates and initializes shared areas (for example, tables of sessions or tables of work processes)
• Starts all further processes of the application server (for example, ICM, gateway, work processes.
• Monitors started processes and other resources
• Communicates with the SAP GUIs
• Communicates with other application servers in the system through the message server
• Manages and triggers periodic tasks.

DATABASE SERVER:

#The Database Layer consists of a central database system containing all of the data in the R/3 System. 

#The database system has two components 

1. the database management system (DBMS), and the database itself.

2. SAP has manufactured its own database named HANA but is compatible with all major databases such as Oracle.All R/3 data is stored in the database. 

For example, 

  1.  the database contains the control and customizing data that determine how your R/3 System runs.  It also contains the program code for your applications. 

2. Applications consist of program code, screen definitions, menus, function modules, and various other components. These are stored in a special section of the database called the R/3 Repository, and are accordingly called repository objects. R/3 repository objects are used in ABAP workbench.

SAP NET-WEAVER:

SAP NetWeaver is the primary technology computing platform of the software company SAP SE, and the technical foundation for many SAP applications. It is a solution stack of SAP's technology products. The SAP NetWeaver Application Server (sometimes referred to as WebAS) is the runtime environment for the SAP applications, and all of the mySAP Business Suite solutions (SRM, CRM, SCM, PLM, ERP, TM ) run on SAP WebAS.
The product is marketed as a service-oriented application and integration platform. It can be used for custom development and integration with other applications and systems, and is built primarily using the ABAP programming language, but also uses C, C++, and Java. It can also be extended with, and interoperate with, technologies such as Microsoft .NET, Java EE, and IBM WebSphere.