Jobs, Tasks, and Commands

TODO: write about the pipeline from job submission to command execution.

Job Statuses

The following table shows the meaning of the different job statuses:

Status	Meaning	Possible next status
`under-construction`	Preparing job for execution	`queued`, `active`
`queued`	Ready to be assigned to available Workers	`active`, `canceled`
`active`	Tasks assigned to Workers for execution	`completed`, `canceled`, `failed`
`completed`	All tasks executed successfully	`queued`
`failed`	Execution of one or more tasks failed after multiple retries by different Workers	`queued`, `canceled`
`cancel-requested`	Request for job cancellation raised by user	`canceled`
`canceled`	Canceled by the user, job terminated immediately on all Workers	`queued`
`requeueing`	Request for requeueing of job raised by user	`queued`
`paused`	Not yet implemented

NOTE :

Requeueing a job when it is completed, i.e. when all its tasks are completed, will requeue all its tasks.
Requeueing a job when some of its tasks are not completed will requeue these tasks only. The completed tasks will not be requeued, and will remain at completed status.

Task Statuses

The following table shows the meaning of the different task statuses:

Status	Meaning	Possible next status
`queued`	Ready to be assigned to an available Worker	`active`, `canceled`
`active`	Assigned to a Worker for execution	`completed`, `canceled`, `failed`, `soft-failed`
`completed`	Task executed succesfully	`queued`
`soft-failed`	Same as `queued`, but has been failed by a Worker in an earlier execution	`queued`, `completed`, `failed`, `canceled`
`failed`	Execution failed after multiple retries by different Workers	`queued`, `canceled`
`canceled`	Canceled by the user, task terminated immediately	`queued`
`paused`	Not yet implemented