74 lines
2.5 KiB
ReStructuredText
74 lines
2.5 KiB
ReStructuredText
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Gateways
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========
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BPMN Model
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----------
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In this section, we'll expand our model by creating alternate paths through the
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workflow depending on the current workflow state, in this case, answers provided
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by the user through forms.
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We've also added a second DMN table to find the cost of the selected shipping
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method, and we updated our order total calculations to incorporate that cost.
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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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- `gateway_types <https://github.com/sartography/spiff-example-cli/blob/master/bpmn/gateway_types.bpmn>`_ workflow
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- `product_prices <https://github.com/sartography/spiff-example-cli/blob/master/bpmn/product_prices.dmn>`_ DMN table
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- `shipping_costs <https://github.com/sartography/spiff-example-cli/blob/master/bpmn/shipping_costs.dmn>`_ DMN table
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Exclusive Gateway
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^^^^^^^^^^^^^^^^^
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Exclusive gateways are used when exactly one alternative can be selected.
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Suppose our products are T-shirts and we offer product C in several colors. After
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the user selects a product, we check to see it if is customizable. Our default
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branch will be 'Not Customizable', but we'll direct the user to a second form
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if they select 'C'; our condition for choosing this branch is a simple python
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expression.
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.. figure:: figures/exclusive_gateway.png
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:scale: 30%
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:align: center
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Flow configuration
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Parallel Gateway
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^^^^^^^^^^^^^^^^
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.. sidebar:: IDs vs Names
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We've assigned descriptive names to all our tasks so far. Text added to
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the Name field will appear in the diagram, so sometimes it's better to
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leave it blank to avoid visual clutter. I've put a description of the
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gateway into the ID field instead.
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Parallel gateways are used when the subsequent tasks do not need to be completed
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in any particular order. The user can complete them in any sequence and the
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workflow will wait for all tasks to be finished before advancing.
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We do not care whether the user chooses a shipping method or enters their
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address first, but they'll need to complete both tasks before continuing.
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We don't need to do any particular configuration for this gateway type.
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.. figure:: figures/parallel_gateway.png
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:scale: 30%
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:align: center
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Parallel Gateway example
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Running The Model
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^^^^^^^^^^^^^^^^^
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If you have set up our example repository, this model can be run with the
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following command:
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.. code-block:: console
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./run.py -p order_product \
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-d bpmn/product_prices.dmn bpmn/shipping_costs.dmn \
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-b bpmn/gateway_types.bpmn
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