Workflows
=========

Cirrus workflows are the component that puts the "pipe" in "pipeline".
Workflows model a transformation of an input item or set of input items with a
process definition into one or more output items via processing from one or
more tasks.  Workflows are composed of one or more "tasks".

Cirrus workflows, being implemented via `AWS Step Functions`_, are written in
the `AWS States Language`_. Workflows are defined in ``state-machine.json`` files and require a companion ``README.md``.

These ``state-machine.json`` files define the entire step function workflow.  A non exhaustive list of configuarable are :

* task definitions
* task input parameters
* task output parameters
* job definition
* job name
* task retry config
* error handling
* resource ARNs

The :doc:`state database <../../70_statedb>` tracks the state of items
processed at the workflow level.

.. _AWS Step Functions:
   https://docs.aws.amazon.com/step-functions/latest/dg/welcome.html
.. _AWS States Language:
   https://docs.aws.amazon.com/step-functions/latest/dg/concepts-amazon-states-language.html

.. toctree::
   :maxdepth: 2
   :caption: Workflow topics:

   definitions
   batch
   chaining
   callbacks