Application Server Java provides a Java platform Enterprise Edition 5 (Java EE5) compliant environment for developing and running Java EE programs. With this installation you can run Java EE applications but not ABAP programs.
The design of SAP NetWeaver Application Server is aimed at providing an exceptionally high level of robustness and supportability for the applications running on it. The architecture of SAP NetWeaver Application Server Java and basic terminology are explained below. For details, see the component-specific documentation.
An SAP NetWeaver Application Server Java system has various instances. An instance is an administrative unit containing various components of an SAP system. The components of an instance are parameterized in a shared instance profile. Each instance is identified by a system ID and an instance number.
A distinction is made between application server instances and system central services instances (SCS instances).
There can be any number of application server instances in an SAP NetWeaver Application Server for Java application. The instances process incoming user requests. A Java application server instance contains one Internet Communication Manager, one SAP start service, and any number of Java server processes.
As well as multiple application server instances, there is one special instance that contains the message server, the enqueue server, and a separate start service - The SCS instance (system central services instance). The SCS instance cannot process any dialog requests - it is used to manage locks, exchange messages, and balance workload in the SAP system.
Java server processes
Internet Communication Manager
SAP Start Service
The following figure shows the components of a Java-only system. For a better overview, series lines have not been used. Incoming requests are accepted by the Internet Communication Manager and distributed to the Java server processes. There is one database for each Java system.