Netscape Application Server-- Managing Distributed Data Synchronization

Administration Guide
Overview Guide
Installation Guide


How Failover Keeps Data Accessible
The distributed data synchronizer is a system-level service that controls how distributed data, such as application session information, is maintained and made accessible across multiple Netscape Application Servers. Each Netscape Application Server is made up of the following four "engines:" Administrative Server (KAS) - An Administrative Server brings up and monitors the other engines and makes sure that any engines that fail are brought up again. Executive Server (KXS) - Only an Executive Server can be the primary synchronization engine (the synchronizer) for a Netscape Application Server cluster. In a cluster of Netscape Application Servers, one of the Executive Servers maintains the distributed (synchronized) information and sets up server roles for all the other servers participating in the cluster. All engines in a cluster know how to access this primary engine and the information that is on this primary engine. Zero or more Java Servers (KJS) Zero or more C++ Servers (KCS) If the Java or C++ engine on a Netscape Application Server fails, the Administrative Server simply restarts the KJS or KCS. However, if the Executive Server fails, the Administrative Server Brings the Executive Server back up in the currently appropriate role.This role is determined in synchronization with other Executive Servers in the cluster, and is not necessarily the previous role Brings down the Java and C++ engines Brings the Java and C++ engines back up For more information about server roles in a cluster, see "What is a Cluster?"