.. _sow:

*********************
Sequence of Workflows
*********************

Another common execution pattern consists of same-session sequential workflows with mulitple concurrent Pipelines with multiple Stages where each Stage consists of several Tasks. We call this a **Sequence of Workflows**.

.. note:: The reader is assumed to be familiar with the :ref:`PST Model <app_model>` and to have read through the :ref:`introduction` of Ensemble Toolkit.

.. note:: This chapter assumes that you have successfully installed Ensemble Toolkit, if not see :ref:`Installation`.

In the following example, we create 2 sequential workflows, each with 2 Pipelines and 3 Stages per Pipeline. For demonstration purposes, each Task does nothing but "sleep" for 3 seconds. The example suggests starting AppManager with autoterminate=False and using appman.terminate() once all pipelines are finished. This allows you to use the same application manager for the second workflow.

You can download the complete code discussed in this section :download:`here <../../../examples/simple/sow.py>` or find it in
your virtualenv under ``share/radical.entk/simple/scripts``.

.. code-block:: bash

    python sow.py

Let's take a look at the complete code in the example. You can generate a more verbose output by setting the environment
variable ``RADICAL_ENTK_VERBOSE=DEBUG``.

A look at the complete code in this section:

.. literalinclude:: ../../../examples/simple/sow.py