2. Architecture

The Ambari Server serves as the collection point for data from across your cluster. Each host has a copy of the Ambari Agent - either installed automatically by the Install wizard or manually - which allows the Ambari Server to control each host. In addition, each host has a copy of Ganglia Monitor (gmond), which collects metric information that is passed to the Ganglia Connector, and then on to the Ambari Server.

 

Figure 1.1. Architectural Overview

 2.1. Sessions

Ambari Web is a client-side JavaScript application, which calls the Ambari REST API (accessible from the Ambari Server) to access cluster information and perform cluster operations. After authenticating to Ambari Web, the application authenticates to the Ambari Server and communication between the browser and server occur asynchronously via the REST API.

	Note
	Ambari Web sessions do not timeout since the application is constantly accessing the REST API, which resets the session timeout. As well, if there is a period of Ambari Web inactivity, the Ambari Web interface is automatically refreshed. Therefore you must explicitly sign out of the Ambari Web interface to destroy the Ambari session with the server.