Client / Server Architecture
A client / server system (a system with client / server architecture) is an Information system, which is divided into components in a certain way. A server component will be making the other components of the system Services. Components that use these services claim to are referred to as clients. Server components can in turn and services from other components to take advantage. General said that each component can be both a server as well as a client of other components occur. Client / server architectures are therefore not rigid Structure. SAP R / 3 is a multi-level client / server system. This summary of layers has nothing to do with the first division the software to do on the hardware. Thus, the extreme cases are possible that all strata are installed on a single computer (central / central system, for example as a demonstration system) or each layer at least one your computer has. Presentation layer the presentation layer is the communication interface between SAP R / 3 applications and users. Your client / server components called the SAP GUI (SAP Graphical User Interface). A SAP GUI generates the graphical interface (eg on your PC / desktop) that will help can make use of SAP R / 3. It prepares the data and provides data to the user on the screen Available. In the reverse direction leads to user actions (such as inputs, mouse movements and mouse clicks) to the application programs further.
Application Layer
The application layer (application layer) of the client / server architecture DV is from a technical perspective, the central part of an SAP R / 3 system. SAP refers to They therefore also called the kernel or as a base system. The application layer consists of one or more application servers and a message server. Usually contains a number of R / 3 application server.
Each application server generates at its launch is series of work processes (= operating system processes, which in its totality the "R / 3 application" form. The message server is used for communication between the application servers. The application layer (application layer) is using the work processes the actual functionality of a (eg, business) application available and further extends its services to the presentation layer:
• R/3-programme be in SAP's own programming language
ABAP (Advanced Business Application Programming) creates and running in the application layer
• ABAP programs communicate with the database management system (RDBMS), the central (relational) database and with the graphical User Interface (SAP GUI) of the presentation layer.
Database layer
The database layer consists of a single central database system which all data are managed in the SAP R / 3 systems. Its components are the database management system and the actual database the database. SAP R / 3 can of database systems from different manufacturers be operated. For the data management of the database server is responsible. It stores all database tables in the database system and submits it to the application layer available.
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