126 lines
4.7 KiB
ReStructuredText
126 lines
4.7 KiB
ReStructuredText
Organizing More Complex Workflows
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=================================
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BPMN Model
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----------
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We'll be using the following files from `spiff-example-cli <https://github.com/sartography/spiff-example-cli>`_.
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- `lanes <https://github.com/sartography/spiff-example-cli/blob/main/tutorial/bpmn/lanes.bpmn>`_ workflow
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- `top_level <https://github.com/sartography/spiff-example-cli/blob/main/bpmn/tutorial/top_level.bpmn>`_ workflow
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- `call_activity <https://github.com/sartography/spiff-example-cli/blob/main/tutorial/bpmn/call_activity.bpmn>`_ workflow
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- `product_prices <https://github.com/sartography/spiff-example-cli/blob/main/tutorial/bpmn/product_prices.dmn>`_ DMN table
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- `shipping_costs <https://github.com/sartography/spiff-example-cli/blob/main/bpmn/tutorial/shipping_costs.dmn>`_ DMN table
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Lanes
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^^^^^
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Lanes are a method in BPMN to distinguish roles for the workflow and who is
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responsible for which actions. In some cases this will be different business
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units, and in some cases this will be different individuals - it really depends
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on the nature of the workflow. Within the BPMN editor, this is done by choosing the
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'Create pool/participant' option from the toolbar on the left hand side.
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We'll modify our workflow to get the customer's payment information and send it
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to an employee who will charge the customer and fulfill the order.
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.. figure:: figures/organization/lanes.png
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:scale: 30%
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:align: center
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Workflow with lanes
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To run this workflow
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.. code-block:: console
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./spiff-bpmn-runner.py -p order_product \
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-d bpmn/tutorial/product_prices.dmn bpmn/tutorial/shipping_costs.dmn \
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-b bpmn/tutorial/lanes.bpmn
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For a simple code example of displaying a tasks lane, see `Handling Lanes`_
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Subprocesses
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^^^^^^^^^^^^
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Subprocesses allow us to conceptualize a group of tasks as a unit by creating a
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mini-workflow inside a task. Subprocess Tasks come in two different flavors: expanded
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or collapsed. The difference between the two types is visual rather than functional.
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It also possible to refer to external processes via a Call Activity Task. This
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allows us to 'call' a separate Process (which might be stored independently of the
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Process we're implementing) by referencing the ID of the called Process, which can simplify
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business logic and make it re-usable.
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We'll expand 'Fulfill Order' into sub tasks -- retrieving the product and shipping
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the order -- and create an Expanded Subprocess.
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We'll also expand our selection of products, adding several new products and the ability
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to customize certain products by size and style in addition to color.
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.. figure:: figures/organization/dmn_table_updated.png
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:scale: 60%
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:align: center
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Updated product list
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.. note::
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I've added what customizations are available for each product in the 'Annotations'
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column of the DMN table. This is not actually used by Spiff; it simply provides
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the option of documenting the decisions contained in the table.
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Since adding gateways for navigating the new options will add a certain amount of
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clutter to our diagram, we'll create a separate workflow for selecting and customizing
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products and refer to that in our main workflow.
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.. figure:: figures/organization/call_activity.png
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:scale: 30%
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:align: center
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Subworkflow for product selection
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We need to make sure the 'Called Element' matches the ID we assigned in the called Process.
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.. figure:: figures/organization/top_level.png
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:scale: 30%
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:align: center
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Parent workflow
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Running the Model
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^^^^^^^^^^^^^^^^^
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.. code-block:: console
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./spiff-bpmn-runner.py -p order_product \
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-d bpmn/tutorial/product_prices.dmn bpmn/tutorial/shipping_costs.dmn \
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-b bpmn/tutorial/top_level.bpmn bpmn/tutorial/call_activity.bpmn
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Example Application Code
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------------------------
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Handling Lanes
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^^^^^^^^^^^^^^
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We are not required to handle lanes in our application, but most of the time we'll
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probably want a way of filtering on lanes and selectively displaying tasks. In
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our sample application, we'll simply display which lane a task belongs to.
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.. code:: python
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def get_task_description(self, task, include_state=True):
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task_spec = task.task_spec
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lane = f'{task_spec.lane}' if task_spec.lane is not None else '-'
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name = task_spec.bpmn_name if task_spec.bpmn_name is not None else '-'
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description = task_spec.description if task_spec.description is not None else 'Task'
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state = f'{task.get_state_name()}' if include_state else ''
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return f'[{lane}] {name} ({description}: {task_spec.bpmn_id}) {state}'
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The tasks lane can be obtained from :code:`task.task_spec.lane`, which will be :code:`None`
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if the task is not part of a lane.
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See the Filtering Tasks Section of :doc:`advanced` more information about working with lanes in Spiff.
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