R/3 Architecture
The SAP R/3 System has a three-tier client/server architecture. All data is stored in a database, and the data is processed in the application layer on the application servers. The SAPgui frontend (presentation layer) is the interface to the user. All three layers are connected to each other with networks. The following graphic depicts the client/server architecture of the R/3 System, and the communication requirements between the presentation and application layers and between the application and database layers:
Depending on your requirements, you can distribute the services to different hosts.
Smaller applications keep the database and the R/3 application on the same host. The large volume of data that passes between the R/3 application and the database (SAP server communication) is processed locally and not through a network.
The presentation layer is usually made up of PCs on which the SAPgui frontend is installed. The SAPgui is not a terminal emulation but an application program that displays R/3 application data graphically. This means that there are no great demands placed on the connection between the SAPgui frontend PCs and the R/3 application (access communication).
Higher processing demands on the R/3 application can be realized by additional application servers (application servers are hosts on which the R/3 application runs).
Very high demands are made on bandwidth and delay time between the application servers and the database server. You need to set up a suitable network connection to meet these demands.
You can speed up and secure data throughput to the database by placing the database on a separate host. The database server host then communicates only with the R/3 application servers. By isolating the database completely from the rest of the corporate network, you prevent unauthorized access to sensitive data and ensure high performance.
For data backup purposes you may need to connect the database server to a dedicated network (SAN = Storage Area Network).
Development Concepts and Architecture
SAP NetWeaver is the leading integration and application platform. The driving force of SAP NetWeaver is to build interoperable, collaborative, and process-centered applications based on its new Service Oriented Architecture (SOA) and Enterprise Services Architecture (ESA). SAP NetWeaver is an application server and Web services package that adheres to industry standards and interacts with Microsofts .NET, IBMs WebSphere, J2EE and SAP ABAP languages.
SAP NetWeaver contains the tools and infrastructure to develop new applications as well as to adapt and migrate existing ones. The SAP NetWeaver philosophy for new applications is to create highly re-usable and service enabled applications, so called composite applications. Existing applications can be adapted to SAP NetWeaver by using the supported industry standards.
This chapter gives an overview of the basic structure of business applications, the new architectural concepts and design patterns for composite applications as well as the standards and SAP technologies that are involved.
