Specifications

10 Optimizing IBM Netfinity Servers for SAP R/3 and Windows NT
middleware, or basis layer, is that portion of an R/3 system that is ported to
specific environments as written in C and C++.
The ABAP/4 Development Workbench is the SAP programming environment
used to develop client/server applications. The programming is done using SAP
4GL ABAP/4 language.
1.6 Client/Server R/3 Architecture
In this section we discuss briefly the fundamental architecture of the R/3 system.
The R/3 system makes a clear distinction between the database, application and
presentation layer but it also identifies the
Internet enabling layer , which is new in
Release 3.1. These layers, which are a part of R/3 system, are fully scalable. The
client/server R/3 architecture is shown in Figure 4.
Figure 4. Three-Tier R/3 Model
1.6.1 Database Layer
The database layer manages the complete data of an organization. The
industry-standard SQL (Structured Query Language) is used for defining and
manipulating all data.
1.6.2 Application Layer
The applications that are based on the DBMS constitute the application layer.
These work with data that they retrieve from these layers and write the new data
back to the database. Each application server has a single
Dispatcher that
manages the work load of the instance. The presentation server interacts with the
dispatcher. End-user requests and units of work are assigned by the dispatcher to
the work processes of the instance for completion.
Work processes are jobs
within the R/3 subsystem that actually perform the work. Each work process is