Agents are managed by the Adaptive Data Agent Service (or simply Agent Service), an application installed behind the firewall. It is a Java application that runs as a Windows Service.
The Agent Service long polls the Adaptive Gateway (a server that brokers communication through the firewall to on-premises instances of the Agent Service), which receives requests from Adaptive servers on behalf of all data agents hosted by that instance of the service. Each installed instance of the Agent Service can host multiple data agents.
The installation includes a desktop utility, the Adaptive Data Agent Service Manager, which you use to perform the initial setup and configuration of the Agent Service.
After the Agent Service is installed, you can upgrade to newer released versions using your web browser when new versions of the Agent Service are available: in the Data Designer, you can see that a new version is available and you can start a download of that software and manually install it on the PC where the Adaptive Data Agent Service Manager is running. You can also develop custom connectors using an SDK and deploy them to the Agent Service.