WorkState

WorkState is a self-documenting Workflow-event state management system.

Note:

This is still in the toy phase, lots of basic requirements are not yet implemented (and some not even thought of yet) The plan is for a clean way to specify how a state-machine should behave, and how it interacts with other state machines. Scopes should be re-usable, and the Engine should ensure that the state-machine is valid at compile time. The Scopes should be loosely connected to whatever is their data-store, hence work with whatever backend you deem, they should even be usable as a state-computer for some external system model.

Unfortunately it is not near there yet. At least the specification is near done :-)

Usage

A minimal example:

from workstate.engine2 import Scope, Engine

class Chapter(Scope):
    'A chapter'
    initial = 'draft'

    class Transitions:
        def proposed__approved(self):
            'Chapter approved'
            return self.marked

    class Events:
        propose = ['draft__proposed']
        approve = ['proposed__approved']
        reject = ['proposed__draft']
        cancel = ['*__canceled']

    class Triggers:
        @trigger('reject', ['proposed'])
        def check_complete(self):
            'Rejects chapter if not complete when landing at proposed state'
            return not self.complete

class Book(Scope):
    'A book'
    initial = 'draft'

    class Events:
        all_approved = ['draft__published']
        cancel = ['*__canceled']

    class Triggers:
        @trigger('all_approved', ['chapter:approved'])
        def publish_book(self):
            'Publishes book if all chapters are approved'
            for chapter in self.get_chapter():
                if chapter.state != 'approved':
                    return False
            return True

class BookEngine(Engine):
    scopes = [Book, Chapter]

This will generate a state-machine graph like so:

Using the engine: (needs to change, invalid samples follow)

>>> sample = doc.instantiate({
>>>     'body': 'Sample document',
>>> })
>>> sample.state
draft

>>> flow = sample.event('propose')
>>> sample.state
draft
>>> flow.events
[('propose', None, 'doc:draft', 'doc:proposed'), ('reject', 'check_complete', 'doc:proposed', 'doc:draft')]

>>> sample.obj['complete'] = True
>>> flow = sample.event('propose')
>>> sample.state
proposed
>>> flow.events
[('propose', None, 'doc:draft', 'doc:proposed')]

>>> flow = sample.event('approve')
Exception: Transition doc:proposed->approved failing on condition check_marked
>>> sample.state
proposed

>>> sample.obj['marked'] = True
>>> flow = sample.event('approve')
Exception: Transition doc:proposed->approved failing on condition check_marked
>>> sample.state
approved
>>> flow.events
[('approve', None, 'doc:proposed', 'doc:approved')]

Defining the State-machine network

For a workflow state-graph we have:

Scopes:	The scope-of or model where the state-system lives
States:	The states of the scope
Transitions:	The transitions between scopes, with optional transition conditions.
Events:	Named causes of sets of transitions
Trigger:	Optional conditional triggers that initiates events at states

Coupling state-machines to your models

Generating documentation

Note: You need to have GraphViz installed.