Server Instance Synchronization (Sun Java System Application Server Enterprise Edition 8.2 High Availability Administration Guide)

Sun Java System Application Server Enterprise Edition 8.2 High Availability Administration Guide

Server Instance Synchronization

If you explicitly start a server instance with the Admin Console or asadmin tool, the server instance is synchronized with the central repository. If this synchronization fails, the server instance doesn’t start.

By default a node agent is configured to start its instances automatically. In this situation, the instances are not synchronized when the node agent is restarted. Each server instance runs with the configuration as stored in its cache. You must not add or remove files in a remote server instance's cache.

To synchronize the instances of a node agent that is configured to start its instances automatically, you must stop and restart the instances.

If a node agent is not configured to start its instances automatically, you must start the instances explicitly when the node agent is restarted. In this situation, repository cache for each server instance is synchronized.

The remote server instance's configuration are treated as cache (all files under nodeagents/na1/server1) and owned by Application Server. In extreme cases, if user removes all files of a remote server instance and restarts the node agent, the remote server instance (for example, server1) will be recreated and all necessary files will be synchronized.

The following files and directories are kept synchronized by the Application Server.

Table 8–1 Files and directories synchronized among remote server instances


File or directory	Description
`applications`	All deployed applications. The parts of this directory (and sub directories) synchronized depend on the applications referred to from the server instance. The Node agent does not synchronize any of the applications because it does not reference any application.
`config`	Contains configuration files for the entire domain. All the files in this directory are synchronized except runtime temporary files, such as, `admch`, `admsn`, `secure.seed`, . `timestamp`, and `__timer_service_shutdown__.dat`.
`config`/`config_name`	Directory to store files to be shared by all instances using config named `config_name`. There will be one such directory for every config defined in domain.xml. All the files in this directory are synchronized to the server instances that are using the `config_name`.
`config`/`config_name/lib/ext`	Folder where Java extension classes (as zip or jar archives) can be dropped. This is used by applications deployed to server instances using config named `config_name`. These jar files are loaded using Java extension mechanism.
docroot	The HTTP document root. In out of the box configuration, all server instances in the domain use the same docroot. The docroot property of the virtual server needs to be configured to make the server instances use a different docroot.
generated	Generated files for Java EE applications and modules, for example, EJB stubs, compiled JSP classes, and security policy files. This directory is synchronized along with applications directory. Therefore, only the directories corresponding to applications referenced by a server instance are synchronized.
lib, lib/classes	Folder where common Java class files or jar and zip archives used by applications deployed to entire domain can be dropped. These classes are loaded using Application Server's class loader. The load order in class loader is: `lib/classes`, `lib/.jar`, `lib/.zip`.
lib/ext	Folder where Java extension classes (as zip or jar archives) used by applications deployed to entire domain can be dropped. These jar files are loaded using Java extension mechanism.