Workflow frameworks for Django [closed]

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Let me give a few notes here as i’m the author of django-fsm and django-viewflow, two projects that could be called “workflow libraries”.

Workflow word itself is a bit overrated. Different kind of libraries and software could call themselves “workflow” but have varying functionality.
The commonality is that a workflow connects the steps of some process into a whole.

General classification

As I see, workflow implementation approaches can be classified as follows:

  • Single/Multiple users – Whether workflow library automates single user tasks or has permission checking/task assignment options.
  • Sequential/Parallel – Sequential workflow is just a state machine pattern implementation and allows to have single active state at a moment. Parallel workflows allow to have several active tasks at once, and probably have some sort of parallel sync/join functionality.
  • Explicit/Implicit – Whether workflow is represented as a separate external entity, or is weaved into some other class, that main responsibility is different.
  • Static/Dynamic – Static workflows are implemented in python code once and then executed, dynamic workflows typically could be configuring by changing contents of workflow database tables. Static workflows are usually better integrated with the rest of the django infrastructure
    like views, forms and templates, and support better customization by usual python constructions like class inheritance. Dynamic workflows assume that you have generic interface that can adapt to any workflow runtime changes.

Of these, the first two could be considered gradual differences, but the other two are fundamental.

Specific packages

Here is brief description what we have nowadays in django, djangopackages and awesome-django project list under workflow section:

  • django.contrib.WizardView – implicit, single user, sequential, static the simplest workflow implementation we could have. It stores intermediate state in the hidden form post data.
  • django-flows – explicit, single user, sequential, static workflow, that keeps flow state in external storage, to allow user to close or open page on another tab and continue working.
  • django-fsm – implicit, multi-user, sequential, static workflow – the most compact and lightweight state machine library. State change events represented just as python methods calls of model class. Has rudimentary support for flow inheritance and overrides. Provides slots for associate permission with state transitions. Allows to use optimistic locking to prevent concurrent state updates.
  • django-states – explicit, multi-user, sequential, static workflow with separate class for state machine and state transitions. Transitions made by passing string name of transition to make_transition method. Provides way for associate permission with state transitions. Has a simple REST generic endpoint for changing model states using AJAX calls. State
    machine inheritance support is not mentioned in the documentation, but class state definition makes it possible with none or few core library modifications.
  • django_xworkflows – explicit, sequential, static workflow with no support for user permission checking, separated class for state machine. Uses tuples for state and transition definitions, makes workflow inheritance support hard.
  • django-workflows – explicit, multi-user, sequential, dynamic workflow storing the state in library provided django models. Has a way to attach permission to workflow transition, and basically thats all.

None of these django state machine libraries have support for parallel workflows, which limits their scope of application a lot. But there are two that do:

  • django-viewflow – explicit, multi-user, parallel, static workflow, with support for parallel tasks execution, complex split and join semantic. Provides helpers to integrate with django functional and class based views, and different background task execution queries, and various pessimistic and optimistic lock strategies to prevent concurrent updates.

  • GoFlow, mentioned in question, tends to be the explicit, multi-user, parallel, dynamic workflow, but it has been forsaken by author for a years.

I see the way to implement dynamic workflow construction functionality on top of django-viewflow. As soon as it is completed, if will close the last and the most sophisticated case for workflow implementation in the django world.

Hope, if anyone was able to read hitherto, now understands the workflow term better, and can do the conscious choice for workflow library for their project.

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