Central
Services 
Definition
The Central Services run on one physical server and are one Java instance.
They comprise the message service and the enqueue service.
Use
The Central Services form the basis of communication and synchronization for the Java cluster.
The Message Service keeps a list of the dispatchers and server processes of the Java cluster. It represents the infrastructure for data exchange (small datasets only) between the participating nodes. The message service also supplies information to the SAP Web Dispatcher about Load Balancing Between Many Java Instances.
The Enqueue Service manages logical database locks, which are set by the executed application program in a server process. The enqueue service also synchronizes data across the cluster.
The section Deployment of a New Application describes how the central components handle the deployment of a new application.
Integration
Central Services are always required when a Java cluster is installed. They are started on a server with their own system number and the system ID (SID) of the whole system.
When Central Services are running, further Java instances are started with the program JControl (see Java Startup and Control Framework).
See also:
Administration of Central Services