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Sun Cluster HA Sun Java System Application Server - Configuration made easy

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The Sun Cluster 3.2 agent for the Sun Java System Application Server (version 8.2) enables two of its important components to be made highly available. The application server's configuration files have a number of settings that are inter-dependent and require careful editing when being changed by hand to make it work in sun cluster environment. This blog begins by outlining the key components of the application server and then provides the source for a tool designed to simplify the configuration of application server.
The two important components of Sun Java Application Server which are made HA are:
1. Domain Administration Server (DAS)
The domain administration server (DAS) is the single process that manages the application server entities like node agents, standalone instances, application clusters, and their configurations.
2. Node agents (NA)
This is the component that makes spanning of a domain across machines possible. It is a standalone process that is started with or without manual intervention and it controls the life cycle of server instances it is responsible for. The server instances host the applications.
A typical example configuration for the Sun Cluster HA Sun Java System Application Server would be as follows:

In order to configure the above set up, you would require to modify:
1. domain.xml
In this file, you would need to modify the http-listeners, IIOP-listeners and the client-hostname under the server-config tag. This is to make the DAS listen on the failover IP. In addition to this, you would need to modify the client-hostname of the respective node-agents to make the node-agents listen on their respective failover IPs. This is to make DAS aware of the IPs on which NAs are bound to.
2. nodeagent.properties
In this file, you would need to modify the agent.client.host entity to make the node agent listen on their respective failover IPs. Make sure that it is the same as specified in the domain.xml for the respective node agents.
3. das.properties (optional)
This file needs to be changed, only if the value of the attribute "agent.das.host" is not the same as specified in domain.xml against the client-hostname tag of DAS.
Sun Cluster Data service HA configuration guide for Sun Java System Application Server provides manual instructions for running Application Server in the Sun cluster environment. This configuration can be done using the script below. This script uses Perl v5.8.2 onwards and requires XPath modules which can be downloaded from http://search.cpan.org/CPAN/authors/id/M/MS/MSERGEANT/XML-XPath-1.13.tar.gz.
Click this link to view and save the perl script.
This script makes modifications to the above configuration files and creates a backup of the original configuration files. If you run this script more than once, the backed up files will be overwritten. Hence it is suggested to have a copy of the original file.
- Sun Cluster Engineering

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