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
● One or several databases
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).
● The Central Services instance.
● The 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