Engine Requests to Control Hub

Engines send requests to Control Hub in the following areas:

Connections

When you start a job for a pipeline that uses a connection, the engine requests the connection properties from Control Hub.

Jobs

Every minute, an engine sends a heartbeat, the last-saved offsets, and the status of all running pipelines to Control Hub so that Control Hub can manage job execution.

Messaging queue

When an engine starts up, it sends the engine version and URL to the messaging queue.

Every five seconds, engines check with the messaging queue to retrieve requests and information sent by Control Hub. When you start, stop, or delete a job, Control Hub sends a pipeline request for specific engines to the messaging queue. The messaging queue retains the request until the receiving engines retrieve them.

Metrics

Every minute, an engine sends metrics for running pipelines to Control Hub.

Tunneling

When WebSocket tunneling for UI communication is enabled for your organization, an engine establishes a WebSocket tunnel with Control Hub when the engine starts up. Control Hub serves as the WebSocket server, and acts as an intermediary between the engine and the web browser.