Cadence: Uber’s Workflow Orchestration Engine

The workflow and activity implementation are hosted and executed in worker processes. These workers long-poll the Cadence server for tasks, execute the tasks by invoking either a workflow or activity implementation, and return the results of the task back to the Cadence server. The Cadence server brokers and persists tasks and events generated during workflow execution, which provides certain scalability and reliability guarantees for workflow executions.

Source: github.com