SAP NetWeaver Application Server is the central foundation for the entire SAP software stack. It also provides a platform for other SAP NetWeaver Application Server components (Portal, XI, and so on), as well as for ABAP and Java applications. The full Java EE standard is supported. SAP NetWeaver Application Server is the further development of the SAP Web Application Server.
Design
Design
The design of SAP NetWeaver Application Server Application Server is aimed at providing an exceptionally high level of robustness and supportability for the applications running on it. SAP NetWeaver Application Server consists of the Application Server ABAP (AS ABAP) and the Application Server Java (AS Java).
AS ABAP
The AS ABAP provides the complete technology and infrastructure to run ABAP applications.
More information: ABAP Application Server
AS Java
The Application Server Java provides a Java platform Enterprise Edition 5 (Java EE5) compliant environment for developing and running Java EE programs.
For more information, see: Architecture of AS Java
Web Server or Web Client
SAP NetWeaver AS can act both as a Web server and as a Web client. In its Web server role, it can accept HTTP requests from any Web client (for example, a browser), process the requests, and send a response back to the client.
If you use SAP NetWeaver as a client, you can create HTTP requests in an application program, and send these requests to a Web server. The client then receives the responses and proceeds on the basis of the responses.
In both cases stateful (state retained in the user context) and stateless requests can be processed.
More information:
Technical Components
An SAP system consists of several application server instances, as well as one or more databases.
In addition to multiple dialog instances users choose to execute, there is a special central instance that contains the message server and the enqueue server. The SCS (System Central Services) for the AS JAVA, the ASCS (ABAP System Central Services). It cannot process any dialog requests.
More information: Application Server
A dialog instance with AS ABAP and AS Java consists of the following components:
- The Internet Communication Manager (ICM) sets up the connection to the Internet. It can process both server and client Web requests. It supports HTTP, HTTPS und SMTP protocols for the AS ABAP. In AS Java the ICM supports the HTTP(S), P4, IIOP and Telnet protocols. SAP NetWeaver AS can be used as a Web server or as a Web client.
- Central services (message server and enqueue server) are used for lock administration, message exchange, and load balancing in the SAP system.
- Each instance is started by the SAP start service, and can be monitored from the Web service interface of the start service.More information: SAP Start Service
- AS ABAP components (in the graphic on the left):
- The dispatcher distributes the requests to the work processes. If all the processes are occupied, the requests are stored in the dispatcher queue.
- The work processes execute ABAP or Java programs.
- Gateway provides the RFC interface between the SAP instances (within an SAP system and beyond system boundaries).
- AS Java components (in the graphic on the right):
- The Server Processes execute Java requests.
- The instance controller controls and monitors the life cycle of the AS Java instance.
The graphic below shows the components of SAP NetWeaver Application Server (in grey). To retain clarity, a few communication channels are not included in the graphic.
Figure 1: SAP NetWeaver Application Server: Dual-Stack Installation
Installation Options
There are the following installation options for SAP NetWeaver AS:
- ABAP system (with integrated VM Container). In the graphic these are the components in the blue box on the left. With this installation you can run ABAP programs and selected SAP Java applications.
- Java system. In the graphic these are the components in the green box on the right. With this installation you can run Java EE applications but not any ABAP programs.
- Dual stack system or ABAP+Java system. These are all the components in the graphic
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