Tasks

A Task is the basic unit of execution in Workflow. Tasks are arranged into a Workflow, and they have Task Rules between them in order to describe the conditions under which they should run.

Task Executions

Much in the same way that a Workflow is instantiated into a Workflow Execution each time it runs, the tasks are instantiated into Task Executions.

A Task Execution has a Status representing what stage of the lifecycle it is in. The possible Status for a Task Execution is:

• init: The task execution has not yet been queued (its dependencies are not yet met)

• queued: The task execution has been assigned to an Executor and is awaiting a worker

• running: The task execution is running on a worker

• success: The task execution finished running without errors

• failed: The task execution had an error during execution and failed to run

• stopping: The task execution was externally requested to shut down when it was running, but not yet finish stopping

• stopped: The task execution is requested to shut down and successfully stopped

• retrying: The task execution failed, but has retry attempts left and will be rescheduled.

Note

In a Workflow Execution, there can be only one running execution of each task, nothing would happen even if you force start a running task.

Task Actions

A Task can perform different actions according to the Task Rule. There are three kinds of actions of a task.

• start: Start a new Task Execution if there is no running execution, otherwise do nothing.

• stop: Stop a running Task Execution.

• restart: Stop the currently running Task Execution and start a new execution.