The model needs one-time data entry which enables a fast and accurate processing of the data. SAP is based on three-tier client/server model. The anatomy of SAP R/3 is as follows, (1)SAP presentation server, (2)SAP application server and (3)SAP database server. Presentation server: The presentation server is actually a program named sapgui. exe. It is actually installed on a user’s workstation. To start it, the user double-clicks on an icon on the desktop or chooses a menu path. When started, the presentation server displays the R/3 menus within a window.
This window is commonly known as the SAPGUI or the user interface. The interface accepts input from the user in the form of keystrokes, mouse clicks, and function keys, and sends these requests to the application server to be processed. The server sends the results back to the SAPGUI which then formats the output for display to the user. Application server: An application server is a set of executables that collectively interpret the ABAP/4 programs and manage the input and output for them. When an application server is started, these executables all start at the same time.
When an application server is stopped, they all shut down together. The number of processes that start up when you bring up application server is defined in a single configuration file called the application server profile. Each application server has a profile that specifies its characteristics when it starts up and while it is running. For example, an application server profile specifies. ?Number of processes and their types. ?Amount of memory each process may use. ?Length of time a user is inactive before being automatically logged off. Database server:
The database server is a set of executables that accept database requests from the application server. These requests are passed on to the RDBMS (relation database management system). The RDBMS sends the back to the database server, which then passes the information back to the application server. The application server in turn passes that information to your ABAP/4 program. There is usually a separate computer dedicated to house the database server, and the RDBMS may run on to computer also, or may be installed on its own computer. Defining an R/3 system:
The simplest definition of an R/3 system is “one database”. In one R/3 system, there is only one database. To expand the definition, R/3 is considered to be all of the components attached to that one database. One R/3 system consists of one database server accessing a single database, one or more application server and one or more presentation servers. By definition, it is all of the components attached to one database. During an implementation, there is usually one system (or one database) assigned to development, one or more systems designated for testing and one assigned to production.
The term R/3 system landscape denotes a description of the number of systems within an SAP installation and how they are designated, such as development, test, or production. The SOP tool (SAP sales and operations planning module) executes the planning procedure for sales, purchase, inventory and forecasts at different levels of production based on plant capacity, storage of materials etc. SOP data such as (1)Period units (days, months, years), (2)Characteristics (company code, plant, materials) and (3)Key figures (sales forecast, purchase and inventory) are contained in the information structure.