Java Cluster Architecture
A Java cluster installation consists of:
●
One or more
Instances of
the AS Java
●
The
Central Services,
which also form an instance
● Database
The different instances can be split up among different physical machines. The Central Services (Message Service and Enqueue Service) are installed on one host that meets possible requirements for high availability.
Minimum Cluster Installation
The following
figure shows the simplest installation of the usage type AS Java. A system
installed in this way can process only requests to Java applications. The
integrated scenario with Java and ABAP is described in the section
SAP NetWeaver
Application Server with ABAP and Java.
The minimal AS Java installation consists of:
● A Java central instance with a dispatcher, a server process, and the Software Deployment Manager (SDM).
● Central Services instance.
● Database.
A
Java Instance
consists of (with the exception of Central Services):
● a Java Dispatcher
● One or several server processes
Large Cluster Installation
The figure below shows a larger Java cluster installation. It consists of four instances, all of which have an instance number and each one can be started, stopped, and monitored separately.
Load Balancing
If you have a large
Java cluster installation, the load is distributed between the available
dialog instances by a load balancer. This scenario with implementation of the
SAP Web Dispatcher is described in the section
Load Balancing of Java
Applications.
Further Information
You will find further information on the cluster architecture in the following sections:
Java Startup and
Control Framework
Load Balancing of Java
Applications
High Availability and
Failover