I always prefer diagram to wordings. Below is an illustration on how a Centralized Agent Configuration works:
When an agent starts up, it reads its bootstrapping file to initialize itself.
OpenSSOAgentBootstrap.properties is stored on the agent machine and indicates the location from where the configuration properties need to be retrieved. Based on the repository setting in OpenSSOAgentBootstrap.properties, it retrieves the rest of its configuration properties. It fetches its configuration from OpenAM Server.
An agent fetches its configuration properties periodically to determine if there have been any configuration changes. Any agent configuration changes made centrally are conveyed to the affected agents, which will react accordingly based on the nature of the updated properties. If the properties affected are hot swappable, the agent can start using the new values without a restart of the underlying agent web container. Notification of the agent when configuration data changes and polling by the agent for configuration changes can be enabled. Agents can also receive notifications of session and policy changes.
For Apache Policy Agent, do not enable notification.