SAP J2EE Engine System Architecture 

Purpose

As a system, the SAP J2EE Engine consists of three logical layers:

·        SAP Java Enterprise Runtime – comprises low-level modules that provide functions such as class loading, cluster communication, persistent configuration data management, and so on. For more information, see SAP Java Enterprise Runtime.

·        Pluggable components – consists of interfaces, libraries and services components that provide various runtime functions and programming APIs. For more information, see Pluggable Components.

·        Applications layer – refers to the applications that are deployed and run on the SAP J2EE Engine. For more information, see Applications.

Features

The SAP J2EE Engine architecture is based on the following general rule: components from the higher level can use components from lower level; whereas components from the lower level are not aware of the APIs of the components from the higher level and therefore cannot use them.

SAP J2EE Engine Architecture

This rule is reflected by the order of starting the system modules: the runtime is started first, then the services (the libraries are loaded, the interfaces resolved at this phase), and the applications are started last. The system is considered as started when all runtime managers and core services components are started properly. For more information on core services, see Developing Services.

Components from the higher level use a set of defined APIs to utilize the functions of the components from the lower level. Pluggable components use the Framework APIs to connect to the SAP Java Enterprise Runtime. Applications use the pluggable components by the APIs that are defined by J2EE 1.3 Specification (and supporting specifications).