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SAP’s Basis technology, for a long time known only as R/3 Basis, has proven itself as a platform thanks to its high-performance architecture. Consequently, SAP NetWeaver Application Server (AS) ABAP is used as the Basis component not only of SAP ERP; it also fulfills this role for SAP components that have a similar structure, such as SAP SCM, SAP SRM, and SAP CRM.
1 Architecture of SAP NetWeaver Application Server ABAP
The underlying technology for SAP components is based on the multitier client/server architecture. In the following sections, you’ll learn how this concept provides a reliable, flexible, and scalable basis for operating complex systems.
In this chapter, we’ll first consider the areas an SAP system administrator needs to influence to ensure that the application runs smoothly. The following sections cover different aspects of system administration, the basis of which is established by the architecture.
1.1 Components of SAP NetWeaver AS ABAP
SAP NetWeaver Application Server (also known as SAP NetWeaver AS and previously SAP Web AS up to Release 6.40) is the underlying technological basis for each SAP component. It supports applications developed in the established and stable programming language ABAP as well as applications developed in Java. Therefore, SAP NetWeaver AS is no longer only the technical basis for SAP applications; it can also be used as the development platform for non-SAP applications.
Depending on the demands you place on SAP NetWeaver AS, you can install it on different instances. Figure 1.1 provides an overview of the installation options available.
SAP Note
This book concentrates on the administration tasks concerning SAP NetWeaver AS ABAP. We don’t discuss administration activities of SAP NetWeaver AS Java.
Figure 1.1 Installation Options for SAP NetWeaver AS
You have three installation options:
- SAP NetWeaver AS ABAP
This provides a complete infrastructure in which ABAP-based applications can be developed and used. - SAP NetWeaver AS Java
This provides a complete infrastructure in which J2EE-based applications can be developed and used. - SAP NetWeaver AS ABAP + Java (Double Stack)
This provides a complete infrastructure in which ABAP-based and J2EE-based applications can be developed and used. This installation focuses on seamless Java/ABAP integration.
One of the key characteristics of SAP NetWeaver AS is that ABAP tables, programs, and application data are saved in the ABAP schema of the database, whereas Java data is saved in the Java schema. Therefore, the ABAP runtime environment can access the ABAP schema of the database, and the Java runtime environment can access the Java schema. The SAP Java Connector (JCo) facilitates integration between the ABAP and Java environments.
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1.2 Client/Server Architecture in SAP NetWeaver
From a software perspective, we distinguish between the following layers in a three-tier client/server architecture:
- Presentation
- Application
- Database
Hardware implementation can move between the following two extremes: all components on one host and one host for each instance in a layer. When determining the best variant, you must consider the planned system usage alongside the requirements for availability and performance (see Figure 1.2).
Operating all three layers of the client/server architecture on one host is only suitable for demonstration or test purposes.
Smaller SAP systems are frequently operated in one central configuration with a separate presentation layer (see Figure 1.2). The database and application run together on one server, and PCs or other workstations are used for the frontend systems. This two-level configuration is frequently used for development or test systems, but also for smaller productive systems.
Figure 1.2 Configuration Variants
If a two-level configuration no longer satisfies user requirements, the database server and application server are separated. The SAP software architecture allows the application layer to be distributed across several instances, which can also be operated on separate hosts. This results in a highly scalable SAP NetWeaver AS...
