Sun Java System Application Server Enterprise Edition 8.1 2005Q2 High Availability Administration Guide

- Previous: Chapter 6 Managing Named Configurations
- Next: Node Agent Placeholders

# What Is a Node Agent?

A node agent is a lightweight process that is required on every machine that hosts server instances, including the machine that hosts the Domain Administration Server (DAS). The node agent:

- Starts, stops, creates and deletes server instances as instructed by the Domain Administration Server.

- Restarts failed server instances.

- Provides a view of the log files of failed servers.

- Synchronizes each server instance’s local configuration repository with the Domain Administration Server’s central repository. Each local repository contains only the information pertinent to that server instance or node agent.

  The following figure illustrates the overall node agent architecture:

When you install the Application Server, a node agent is created by default with the host name of the machine. This node agent must be manually started on the local machine before it runs.

You can create and delete server instances even if the node agent is not running. However, the node agent must be running before you use it to start and stop server instances.

If you stop the node agent, the server instances it manages are stopped too.

A node agent services a single domain. If a machine hosts instances running in multiple domains, it must run multiple node agents.

## See Also

- Deploying Node Agents

- Node Agent Placeholders

- Node Agent and Domain Administration Server Synchronization

- To Create a Node Agent Placeholder

- Creating a Node Agent

- Starting a Node Agent

- Stopping a Node Agent

- Deleting a Node Agent

- Previous: Chapter 6 Managing Named Configurations
- Next: Node Agent Placeholders

- © 2010, Oracle Corporation and/or its affiliates