shoobx.wfmc 4.3.1

Participants

We’ve declared some applications, and we’ve wired them up to activities, but we still haven’t specified any application code. Before we can specify application code, we need to consider who will be performing the application. Workflow applications are normally executed by people, or other external actors. As with applications, process definitions allow participants in the workflow to be declared and identified with activities. We declare participants much as we declare applications, except without parameters:

>>> pd.defineParticipants(
...     author   = process.Participant(),
...     reviewer = process.Participant(),
...     )

In this case, we happened to reuse an activity name for one, but not both of the participants. Having defined these participants, we can associate them with activities:

>>> pd.activities['author'].definePerformer('author')
>>> pd.activities['review'].definePerformer('reviewer')

Application Integration

To use a process definition to control application logic, we need to associate it with an “integration” object.

When a process needs to get a participant, it calls createParticipant on its integration attribute, passing the process id and the performer id. If an activity doesn’t have a performer, then the procedure above is used with an empty performer id.

Similarly, when a process needs a work item, it calls createWorkItem on its integration attribute, passing the process id and the application id.

Work items provide a start method, which is used to start the work and pass input arguments. It is the responsibility of the work item, at some later time, to call the workItemFinished method on the activity, to notify the activity that the work item was completed. Output parameters are passed to the workItemFinished method.

A simple way to create integration objects is with shoobx.wfmc.attributeintegration.AttributeIntegration.

>>> from shoobx.wfmc.attributeintegration import AttributeIntegration
>>> integration = AttributeIntegration()
>>> pd.integration = integration

We’ll start by defining a simple Participant class:

>>> import zope.interface
>>> from shoobx.wfmc import interfaces

>>> @zope.interface.implementer(interfaces.IParticipant)
... class Participant(object):
...     zope.component.adapts(interfaces.IActivity)
...
...     def __init__(self, activity, process):
...         self.activity = activity

We set attributes on the integration for each participant:

>>> integration.authorParticipant   = Participant
>>> integration.reviewerParticipant = Participant

We also define an attribute for participants for activities that don’t have performers:

>>> integration.Participant = Participant

Now we’ll define our work-items. First we’ll define some classes:

>>> work_list = []

>>> @zope.interface.implementer(interfaces.IWorkItem)
... class ApplicationBase:
...     zope.component.adapts(interfaces.IParticipant)
...
...     def __init__(self, participant, process, activity):
...         self.participant = participant
...         work_list.append(self)
...
...     def start(self, args):
...         pass
...
...     def finish(self):
...         self.participant.activity.workItemFinished(self)

>>> class Review(ApplicationBase):
...     def finish(self, publish):
...         output = {'publish': publish}
...         self.participant.activity.workItemFinished(self, output)

>>> class Publish(ApplicationBase):
...     def start(self, args):
...         print ("Published")
...         self.finish()

>>> class Reject(ApplicationBase):
...     def start(self, args):
...         print ("Rejected")
...         self.finish()

and then we’ll hook them up with the integration object:

>>> integration.authorWorkItem  = ApplicationBase
>>> integration.reviewWorkItem  = Review
>>> integration.publishWorkItem = Publish
>>> integration.rejectWorkItem  = Reject

Using workflow processes

To use a process definition, instantiate it and call its start method to start execution:

>>> proc = pd()
>>> proc.start()
... # doctest: +NORMALIZE_WHITESPACE
ProcessStarted(Process('sample'))
Transition(None, Activity('sample.author'))
ActivityStarted(Activity('sample.author'))
WorkItemStarting('author')
WorkItemStarted('author')

We transition into the author activity and wait for work to get done. To move forward, we need to get at the authoring work item, so we can finish it. Our work items add themselves to a work list, so we can get the item from the list.

>>> item = work_list.pop()

Now we can finish the work item, by calling its finish method:

>>> item.finish()
WorkItemFinished('author')
ActivityFinished(Activity('sample.author'))
Transition(Activity('sample.author'), Activity('sample.review'))
ActivityStarted(Activity('sample.review'))
WorkItemStarting('review')
WorkItemStarted('review')

We see that we transitioned to the review activity. Note that the finish method isn’t a part of the workflow APIs. It was defined by our sample classes. Other applications could use different mechanisms.

Now, we’ll finish the review process by calling the review work item’s finish. We’ll pass False, indicating that the content should not be published:

>>> work_list.pop().finish(False)
WorkItemFinished('review')
ActivityFinished(Activity('sample.review'))
Transition(Activity('sample.review'), Activity('sample.reject'))
ActivityStarted(Activity('sample.reject'))
WorkItemStarting('reject')
Rejected
WorkItemFinished('reject')
ActivityFinished(Activity('sample.reject'))
ProcessFinished(Process('sample'))
WorkItemStarted('reject')

Ordering output transitions

Normally, outgoing transitions are ordered in the order of transition definition and all transitions from a given activity are used.

If transitions are defined in an inconvenient order, then the workflow might not work as expected. For example, let’s modify the above process by switching the order of definition of some of the transitions. We’ll reuse our integration object from the previous example by passing it to the definition constructor:

>>> pd = process.ProcessDefinition('sample', integration)
>>> pdfactory.register(pd)

>>> pd.defineActivities(
...     author = process.ActivityDefinition(),
...     review = process.ActivityDefinition(),
...     publish = process.ActivityDefinition(),
...     reject = process.ActivityDefinition(),
...     )
>>> pd.defineTransitions(
...     process.TransitionDefinition('author', 'review'),
...     process.TransitionDefinition('review', 'reject'),
...     process.TransitionDefinition(
...         'review', 'publish',
...         condition=lambda proc: proc.workflowRelevantData.publish),
...     )

>>> pd.defineApplications(
...     author = process.Application(),
...     review = process.Application(
...         process.OutputParameter('publish')),
...     publish = process.Application(),
...     reject = process.Application(),
...     )

>>> pd.activities['author'].addApplication('author')
>>> pd.activities['review'].addApplication('review', ['publish'])
>>> pd.activities['publish'].addApplication('publish')
>>> pd.activities['reject'].addApplication('reject')

>>> pd.defineParticipants(
...     author   = process.Participant(),
...     reviewer = process.Participant(),
...     )

>>> pd.activities['author'].definePerformer('author')
>>> pd.activities['review'].definePerformer('reviewer')

and run our process:

>>> proc = pd()
>>> proc.start()
... # doctest: +NORMALIZE_WHITESPACE
ProcessStarted(Process('sample'))
Transition(None, Activity('sample.author'))
ActivityStarted(Activity('sample.author'))
WorkItemStarting('author')
WorkItemStarted('author')

>>> work_list.pop().finish()
WorkItemFinished('author')
ActivityFinished(Activity('sample.author'))
Transition(Activity('sample.author'), Activity('sample.review'))
ActivityStarted(Activity('sample.review'))
WorkItemStarting('review')
WorkItemStarted('review')

This time, we’ll say that we should publish:

>>> work_list.pop().finish(True)
WorkItemFinished('review')
ActivityFinished(Activity('sample.review'))
Transition(Activity('sample.review'), Activity('sample.reject'))
ActivityStarted(Activity('sample.reject'))
WorkItemStarting('reject')
Rejected
WorkItemFinished('reject')
ActivityFinished(Activity('sample.reject'))
ProcessFinished(Process('sample'))
WorkItemStarted('reject')

But we went to the reject activity anyway. Why? Because transitions are tested in order. Because the transition to the reject activity was tested first and had no condition, we followed it without checking the condition for the transition to the publish activity. We can fix this by specifying outgoing transitions on the reviewer activity directly. To do this, we’ll also need to specify ids in our transitions. Let’s redefine the process:

>>> pd = process.ProcessDefinition('sample', integration)
>>> pdfactory.register(pd)

>>> pd.defineActivities(
...     author = process.ActivityDefinition(),
...     review = process.ActivityDefinition(),
...     publish = process.ActivityDefinition(),
...     reject = process.ActivityDefinition(),
...     )
>>> pd.defineTransitions(
...     process.TransitionDefinition('author', 'review'),
...     process.TransitionDefinition('review', 'reject', id='reject'),
...     process.TransitionDefinition(
...         'review', 'publish', id='publish',
...         condition=lambda proc: proc.workflowRelevantData.publish),
...     )

>>> pd.defineApplications(
...     author = process.Application(),
...     review = process.Application(
...         process.OutputParameter('publish')),
...     publish = process.Application(),
...     reject = process.Application(),
...     )

>>> pd.activities['author'].addApplication('author')
>>> pd.activities['review'].addApplication('review', ['publish'])
>>> pd.activities['publish'].addApplication('publish')
>>> pd.activities['reject'].addApplication('reject')

>>> pd.defineParticipants(
...     author   = process.Participant(),
...     reviewer = process.Participant(),
...     )

>>> pd.activities['author'].definePerformer('author')
>>> pd.activities['review'].definePerformer('reviewer')

>>> pd.activities['review'].addOutgoing('publish')
>>> pd.activities['review'].addOutgoing('reject')

Now, when we run the process, we’ll go to the publish activity as expected:

>>> proc = pd()
>>> proc.start()
... # doctest: +NORMALIZE_WHITESPACE
ProcessStarted(Process('sample'))
Transition(None, Activity('sample.author'))
ActivityStarted(Activity('sample.author'))
WorkItemStarting('author')
WorkItemStarted('author')

>>> work_list.pop().finish()
WorkItemFinished('author')
ActivityFinished(Activity('sample.author'))
Transition(Activity('sample.author'), Activity('sample.review'))
ActivityStarted(Activity('sample.review'))
WorkItemStarting('review')
WorkItemStarted('review')

>>> work_list.pop().finish(True)
WorkItemFinished('review')
ActivityFinished(Activity('sample.review'))
Transition(Activity('sample.review'), Activity('sample.publish'))
ActivityStarted(Activity('sample.publish'))
WorkItemStarting('publish')
Published
WorkItemFinished('publish')
ActivityFinished(Activity('sample.publish'))
ProcessFinished(Process('sample'))
WorkItemStarted('publish')

Let’s see the other way also, where we should transition to reject:

>>> proc = pd()
>>> proc.start()
... # doctest: +NORMALIZE_WHITESPACE
ProcessStarted(Process('sample'))
Transition(None, Activity('sample.author'))
ActivityStarted(Activity('sample.author'))
WorkItemStarting('author')
WorkItemStarted('author')

>>> work_list.pop().finish()
WorkItemFinished('author')
ActivityFinished(Activity('sample.author'))
Transition(Activity('sample.author'), Activity('sample.review'))
ActivityStarted(Activity('sample.review'))
WorkItemStarting('review')
WorkItemStarted('review')

>>> work_list.pop().finish(False)
WorkItemFinished('review')
ActivityFinished(Activity('sample.review'))
Transition(Activity('sample.review'), Activity('sample.reject'))
ActivityStarted(Activity('sample.reject'))
WorkItemStarting('reject')
Rejected
WorkItemFinished('reject')
ActivityFinished(Activity('sample.reject'))
ProcessFinished(Process('sample'))
WorkItemStarted('reject')

Complex Flows

Lets look at a more complex example. In this example, we’ll extend the process to work with multiple reviewers. We’ll also make the work-list handling a bit more sophisticated. We’ll also introduce some new concepts:

• splits and joins

• process arguments

Consider the publication process shown below:

Author:      Tech          Tech          Editorial
             Reviewer 1:   Reviewer 2:   Reviewer:
===========  ===========   ===========   ==============
                                                         ---------
     ----------------------------------------------------| Start |
    /                                                    ---------
    |
    V
-----------
| Prepare |<------------------------------\
-----------                                \
    |        ------------                   \
    |        | Tech     |--------------- \   \
    |------->| Review 1 |                 V   |
    |        ------------  ----------    -------------
     \                     | Tech   |    | Editorial |   ----------
       ------------------->| Review |--->| Review    |-->| Reject |
                           | 2      |    -------------   ----------
                           ----------      |      |
-----------                               /        \
| Prepare |                              /          \--------\
| Final   |<----------------------------/                    |
-----------                                                  |
   ^   |                                 ----------          V
   |    \------------------------------->| Review |      -----------
    \                                    | Final  |----->| Publish |
     ------------------------------------|        |      -----------
                                         ----------

Here we’ve arranged the process diagram into columns, with the activities for each participant. We have four participants, the author, two technical reviewers, and an editorial reviewer. The author prepares a draft. The author sends the draft to both technical reviewers for review. When the technical reviews have completed, the editorial review does an initial editorial review. Based on the technical reviews, the editor may choose to:

• Reject the document

• Publish the document as is

• Request technical changes (based on the technical reviewers’ comments), or

• Request editorial changes.

If technical changes are required, the work flows back to the “Prepare” activity. If editorial changes are necessary, then work flows to the “Prepare Final” activity. When the author has made the editorial changes, work flows to “Review Final”. The editor may request additional changes, in which case, work flows back to “Prepare Final”, otherwise, the work flows to “Publish”.

This example illustrates different kinds of “joins” and “splits”. The term “join” refers to the way incoming transitions to an activity are handled. There are two kinds of joins: “and” and “xor”. With an “and” join, the activity waits for each of the incoming transitions. In this example, the inputs to the “Editorial Review” activity form an “and” join. Editorial review waits until each of the technical reviews are completed. The rest of the joins in this example are “xor” joins. The activity starts on any transition into the activity.

The term “split” refers to way outgoing transitions from an activity are handled. Normally, exactly one transition out of an activity is used. This is called an “xor” split. With an “and” split, all transitions with boolean conditions that evaluate to True are used. In this example, the “Prepare” activity has an “and” split. Work flows simultaneously to the two technical review activities. The rest of the splits in this example are “xor” splits.

Lets create our new workflow process. We’ll reuse our existing integration object:

>>> Publication = process.ProcessDefinition('Publication')
>>> Publication.integration = integration
>>> pdfactory.register(Publication)

>>> Publication.defineActivities(
...     start   = process.ActivityDefinition("Start"),
...     prepare = process.ActivityDefinition("Prepare"),
...     tech1   = process.ActivityDefinition("Technical Review 1"),
...     tech2   = process.ActivityDefinition("Technical Review 2"),
...     review  = process.ActivityDefinition("Editorial Review"),
...     final   = process.ActivityDefinition("Final Preparation"),
...     rfinal  = process.ActivityDefinition("Review Final"),
...     publish = process.ActivityDefinition("Publish"),
...     reject  = process.ActivityDefinition("Reject"),
...     )

Here, we’ve passed strings to the activity definitions providing names. Names must be either unicode or ASCII strings.

We define our transitions:

>>> Publication.defineTransitions(
...     process.TransitionDefinition('start', 'prepare'),
...     process.TransitionDefinition('prepare', 'tech1'),
...     process.TransitionDefinition('prepare', 'tech2'),
...     process.TransitionDefinition('tech1', 'review'),
...     process.TransitionDefinition('tech2', 'review'),
...
...     process.TransitionDefinition(
...         'review', 'reject',
...         condition=lambda proc: not proc.workflowRelevantData.publish
...         ),
...     process.TransitionDefinition(
...         'review', 'prepare',
...         condition=lambda proc: proc.workflowRelevantData.tech_changes
...         ),
...     process.TransitionDefinition(
...         'review', 'final',
...         condition=lambda proc: proc.workflowRelevantData.ed_changes
...         ),
...     process.TransitionDefinition('review', 'publish'),
...
...     process.TransitionDefinition('final', 'rfinal'),
...     process.TransitionDefinition(
...         'rfinal', 'final',
...         condition=lambda proc: proc.workflowRelevantData.ed_changes
...         ),
...     process.TransitionDefinition('rfinal', 'publish'),
...     )

We specify our “and” split and join:

>>> Publication.activities['prepare'].andSplit(True)
>>> Publication.activities['review'].andJoin(True)

We define our participants and applications:

>>> Publication.defineParticipants(
...     author   = process.Participant("Author"),
...     tech1    = process.Participant("Technical Reviewer 1"),
...     tech2    = process.Participant("Technical Reviewer 2"),
...     reviewer = process.Participant("Editorial Reviewer"),
...     )

>>> Publication.defineApplications(
...     prepare = process.Application(),
...     tech_review = process.Application(
...         process.OutputParameter('publish'),
...         process.OutputParameter('tech_changes'),
...         ),
...     ed_review = process.Application(
...         process.InputParameter('publish1'),
...         process.InputParameter('tech_changes1'),
...         process.InputParameter('publish2'),
...         process.InputParameter('tech_changes2'),
...         process.OutputParameter('publish'),
...         process.OutputParameter('tech_changes'),
...         process.OutputParameter('ed_changes'),
...         ),
...     publish = process.Application(),
...     reject = process.Application(),
...     final = process.Application(),
...     rfinal = process.Application(
...         process.OutputParameter('ed_changes'),
...         ),
...     )

>>> Publication.activities['prepare'].definePerformer('author')
>>> Publication.activities['prepare'].addApplication('prepare')

>>> Publication.activities['tech1'].definePerformer('tech1')
>>> Publication.activities['tech1'].addApplication(
...     'tech_review', ['publish1', 'tech_changes1'])

>>> Publication.activities['tech2'].definePerformer('tech2')
>>> Publication.activities['tech2'].addApplication(
...     'tech_review', ['publish2', 'tech_changes2'])

>>> Publication.activities['review'].definePerformer('reviewer')
>>> Publication.activities['review'].addApplication(
...     'ed_review',
...     ['publish1', 'tech_changes1', 'publish2', 'tech_changes2',
...      'publish', 'tech_changes', 'ed_changes'],
...     )

>>> Publication.activities['final'].definePerformer('author')
>>> Publication.activities['final'].addApplication('final')

>>> Publication.activities['rfinal'].definePerformer('reviewer')
>>> Publication.activities['rfinal'].addApplication(
...     'rfinal', ['ed_changes'],
...     )

>>> Publication.activities['publish'].addApplication('publish')
>>> Publication.activities['reject'].addApplication('reject')

We want to be able to specify an author when we start the process. We’d also like to be told the final disposition of the process. To accomplish this, we’ll define parameters for our process:

>>> Publication.defineParameters(
...     process.InputParameter('author'),
...     process.OutputParameter('publish'),
...     )

Now that we’ve defined the process, we need to provide participant and application components. Let’s start with our participants. Rather than sharing a single work list, we’ll give each user their own work list. We’ll also create preexisting participants and return them. Finally, we’ll create multiple authors and use the selected one:

>>> class User:
...     def __init__(self):
...         self.work_list = []

>>> authors = {'bob': User(), 'ted': User(), 'sally': User()}

>>> reviewer = User()
>>> tech1 = User()
>>> tech2 = User()

>>> class Author(Participant):
...     def __init__(self, activity, process):
...         Participant.__init__(self, activity, process)
...         author_name = activity.process.workflowRelevantData.author
...         print(("Author `%s` selected" % author_name))
...         self.user = authors[author_name]

In this example, we need to define a separate attribute for each participant:

>>> integration.authorParticipant = Author

When the process is created, the author name will be passed in and assigned to the workflow-relevant data. Our author class uses this information to select the named user.

>>> class Reviewer(Participant):
...     user = reviewer
>>> integration.reviewerParticipant = Reviewer

>>> class Tech1(Participant):
...     user = tech1
>>> integration.tech1Participant = Tech1

>>> class Tech2(Participant):
...     user = tech2
>>> integration.tech2Participant = Tech2

We’ll use our orginal participation class for activities without performers:

>>> integration.Participant = Participant

Now we’ll create our applications. Let’s start with our author:

>>> @zope.interface.implementer(interfaces.IWorkItem)
... class ApplicationBase(object):
...     zope.component.adapts(interfaces.IParticipant)
...
...     def __init__(self, participant, process, activity):
...         self.participant = participant
...         self.activity = participant.activity
...         participant.user.work_list.append(self)
...
...     def start(self, args):
...         pass
...
...     def finish(self):
...         self.participant.activity.workItemFinished(self)

>>> class Prepare(ApplicationBase):
...
...     def summary(self):
...         process = self.activity.process
...         doc = getattr(process.applicationRelevantData, 'doc', '')
...         if doc:
...             print ('Previous draft:')
...             print (doc)
...             print ('Changes we need to make:')
...             for change in process.workflowRelevantData.tech_changes:
...                 print (change)
...         else:
...             print ('Please write the initial draft')
...
...     def finish(self, doc):
...         self.activity.process.applicationRelevantData.doc = doc
...         super(Prepare, self).finish()

>>> integration.prepareWorkItem = Prepare

Since we used the prepare application for revisions as well as initial preparation, we provide a summary method to show us what we have to do.

Here we get the document created by the author passed in as an argument to the finish method. In a more realistic implementation, the author task would create the document at the start of the task and provide a user interface for the user to edit it. We store the document as application-relevant data, since we’ll want reviewers to be able to access it, but we don’t need it directly for workflow control.

>>> class TechReview(ApplicationBase):
...
...     def getDoc(self):
...         return self.activity.process.applicationRelevantData.doc
...
...     def finish(self, decision, changes):
...         output = {'publish': decision, 'tech_changes': changes}
...         self.activity.workItemFinished(self, output)

>>> integration.tech_reviewWorkItem = TechReview

Here, we provided a method to access the original document.

>>> class Review(TechReview):
...
...     def start(self, args):
...         publish1 = args['publish1']
...         publish2 = args['publish2']
...         changes1 = args['tech_changes1']
...         changes2 = args['tech_changes2']
...         if not (publish1 and publish2):
...             output = {'publish': False,
...                       'tech_changes': changes1 + changes2,
...                       'ed_changes': ()}
...             # Reject if either tech reviewer rejects
...             self.activity.workItemFinished(
...                 self, output)
...
...         if changes1 or changes2:
...             output = {'publish': True,
...                       'tech_changes': changes1 + changes2,
...                       'ed_changes': ()}
...             # we won't do anything if there are tech changes
...             self.activity.workItemFinished(
...                 self, output)
...
...     def finish(self, ed_changes):
...         output = {'publish': True, 'tech_changes': (), 'ed_changes': ed_changes}
...         self.activity.workItemFinished(self, output)

>>> integration.ed_reviewWorkItem = Review

In this implementation, we decided to reject outright if either technical editor recommended rejection and to send work back to preparation if there are any technical changes. We also subclassed TechReview to get the getDoc method.

We’ll reuse the publish and reject application from the previous example.

>>> class Final(ApplicationBase):
...
...     def summary(self):
...         process = self.activity.process
...         doc = getattr(process.applicationRelevantData, 'doc', '')
...         print ('Previous draft:')
...         print((self.activity.process.applicationRelevantData.doc))
...         print ('Changes we need to make:')
...         for change in process.workflowRelevantData.ed_changes:
...            print (change)
...
...     def finish(self, doc):
...         self.activity.process.applicationRelevantData.doc = doc
...         super(Final, self).finish()

>>> integration.finalWorkItem = Final

In our this application, we simply update the document to reflect changes.

>>> class ReviewFinal(TechReview):
...
...     def finish(self, ed_changes):
...         output = {'ed_changes': ed_changes}
...         self.activity.workItemFinished(self, output)

>>> integration.rfinalWorkItem = ReviewFinal

Our process now returns data. When we create a process, we need to supply an object that it can call back to:

>>> @zope.interface.implementer(interfaces.IProcessContext)
... class PublicationContext:
...
...     def processFinished(self, process, decision):
...         self.decision = decision

Now, let’s try out our process:

>>> context = PublicationContext()
>>> proc = Publication(context)
>>> proc.start('bob')
ProcessStarted(Process('Publication'))
Transition(None, Activity('Publication.start'))
ActivityStarted(Activity('Publication.start'))
ActivityFinished(Activity('Publication.start'))
Author `bob` selected
Transition(Activity('Publication.start'), Activity('Publication.prepare'))
ActivityStarted(Activity('Publication.prepare'))
WorkItemStarting('prepare')
WorkItemStarted('prepare')

We should have added an item to bob’s work list. Let’s get it and finish it, submitting a document:

>>> item = authors['bob'].work_list.pop()
>>> item.finish("I give my pledge, as an American\n"
...             "to save, and faithfully to defend from waste\n"
...             "the natural resources of my Country.")
WorkItemFinished('prepare')
ActivityFinished(Activity('Publication.prepare'))
Transition(Activity('Publication.prepare'), Activity('Publication.tech1'))
ActivityStarted(Activity('Publication.tech1'))
WorkItemStarting('tech_review')
WorkItemStarted('tech_review')
Transition(Activity('Publication.prepare'), Activity('Publication.tech2'))
ActivityStarted(Activity('Publication.tech2'))
WorkItemStarting('tech_review')
WorkItemStarted('tech_review')

Notice that we transitioned to two activities, tech1 and tech2. This is because the prepare activity has an “and” split. Now we’ll do a tech review. Let’s see what tech1 has:

>>> item = tech1.work_list.pop()
>>> print((item.getDoc()))
I give my pledge, as an American
to save, and faithfully to defend from waste
the natural resources of my Country.

Let’s tell the author to change “American” to “Earthling”:

>>> item.finish(True, ['Change "American" to "Earthling"'])
WorkItemFinished('tech_review')
ActivityFinished(Activity('Publication.tech1'))
Transition(Activity('Publication.tech1'), Activity('Publication.review'))

Here we transitioned to the editorial review activity, but we didn’t start it. This is because the editorial review activity has an “and” join, meaning that it won’t start until both transitions have occurred.

Now we’ll do the other technical review:

>>> item = tech2.work_list.pop()
>>> item.finish(True, ['Change "Country" to "planet"'])
WorkItemFinished('tech_review')
ActivityFinished(Activity('Publication.tech2'))
Transition(Activity('Publication.tech2'), Activity('Publication.review'))
ActivityStarted(Activity('Publication.review'))
WorkItemStarting('ed_review')
WorkItemFinished('ed_review')
ActivityFinished(Activity('Publication.review'))
Author `bob` selected
Transition(Activity('Publication.review'), Activity('Publication.prepare'))
ActivityStarted(Activity('Publication.prepare'))
WorkItemStarting('prepare')
WorkItemStarted('prepare')
WorkItemStarted('ed_review')

Now when we transitioned to the editorial review activity, we started it, because each of the input transitions had happened. Our editorial review application automatically sent the work back to preparation, because there were technical comments. Of course the author is still bob. Let’s address the comments:

>>> item = authors['bob'].work_list.pop()
>>> item.summary()
Previous draft:
I give my pledge, as an American
to save, and faithfully to defend from waste
the natural resources of my Country.
Changes we need to make:
Change "American" to "Earthling"
Change "Country" to "planet"

>>> item.finish("I give my pledge, as an Earthling\n"
...             "to save, and faithfully to defend from waste\n"
...             "the natural resources of my planet.")
WorkItemFinished('prepare')
ActivityFinished(Activity('Publication.prepare'))
Transition(Activity('Publication.prepare'), Activity('Publication.tech1'))
ActivityStarted(Activity('Publication.tech1'))
WorkItemStarting('tech_review')
WorkItemStarted('tech_review')
Transition(Activity('Publication.prepare'), Activity('Publication.tech2'))
ActivityStarted(Activity('Publication.tech2'))
WorkItemStarting('tech_review')
WorkItemStarted('tech_review')

As before, after completing the initial edits, we start the technical review activities again. We’ll review it again. This time, we have no comments, because the author applied our requested changes:

>>> item = tech1.work_list.pop()
>>> item.finish(True, [])
WorkItemFinished('tech_review')
ActivityFinished(Activity('Publication.tech1'))
Transition(Activity('Publication.tech1'), Activity('Publication.review'))

>>> item = tech2.work_list.pop()
>>> item.finish(True, [])
WorkItemFinished('tech_review')
ActivityFinished(Activity('Publication.tech2'))
Transition(Activity('Publication.tech2'), Activity('Publication.review'))
ActivityStarted(Activity('Publication.review'))
WorkItemStarting('ed_review')
WorkItemStarted('ed_review')

This time, we are left in the technical review activity because there weren’t any technical changes. We’re ready to do our editorial review. We’ll request an editorial change:

>>> item = reviewer.work_list.pop()
>>> print((item.getDoc()))
I give my pledge, as an Earthling
to save, and faithfully to defend from waste
the natural resources of my planet.

>>> item.finish(['change "an" to "a"'])
WorkItemFinished('ed_review')
ActivityFinished(Activity('Publication.review'))
Author `bob` selected
Transition(Activity('Publication.review'), Activity('Publication.final'))
ActivityStarted(Activity('Publication.final'))
WorkItemStarting('final')
WorkItemStarted('final')

Because we requested editorial changes, we transitioned to the final editing activity, so that the author (still bob) can make the changes:

>>> item = authors['bob'].work_list.pop()
>>> item.summary()
Previous draft:
I give my pledge, as an Earthling
to save, and faithfully to defend from waste
the natural resources of my planet.
Changes we need to make:
change "an" to "a"

>>> item.finish("I give my pledge, as a Earthling\n"
...             "to save, and faithfully to defend from waste\n"
...             "the natural resources of my planet.")
WorkItemFinished('final')
ActivityFinished(Activity('Publication.final'))
Transition(Activity('Publication.final'), Activity('Publication.rfinal'))
ActivityStarted(Activity('Publication.rfinal'))
WorkItemStarting('rfinal')
WorkItemStarted('rfinal')

We transition to the activity for reviewing the final edits. We review the document and approve it for publication:

>>> item = reviewer.work_list.pop()
>>> print((item.getDoc()))
I give my pledge, as a Earthling
to save, and faithfully to defend from waste
the natural resources of my planet.

>>> item.finish([])
WorkItemFinished('rfinal')
ActivityFinished(Activity('Publication.rfinal'))
Transition(Activity('Publication.rfinal'), Activity('Publication.publish'))
ActivityStarted(Activity('Publication.publish'))
WorkItemStarting('publish')
Published
WorkItemFinished('publish')
ActivityFinished(Activity('Publication.publish'))
ProcessFinished(Process('Publication'))
WorkItemStarted('publish')

At this point, the rest of the process finished automatically. In addition, the decision was recorded in the process context object:

>>> proc.workflowRelevantData.publish
True

Coming Soon

• Timeouts/exceptions

See also

http://www.wfmc.org http://www.wfmc.org/standards/standards.htm

Descriptions

Most process elements can have names and descriptions.

>>> pd.__name__
'Publication'

>>> pd.description
'This is the sample process'

>>> pd.applications['prepare'].__name__
'Prepare'

>>> pd.applications['prepare'].description
'Prepare the initial draft'

>>> pd.activities['tech1'].__name__
'Technical Review 1'

>>> pd.activities['tech1'].description
'This is the first Technical Review.'

>>> pd.participants['tech1'].__name__
'Technical Reviewer 1'

>>> pd.participants['tech1'].description
'He is a smart guy.'

>>> sorted([item.__name__ for item in pd.transitions])
    ['Transition', 'Transition', 'Transition', 'Transition',
    'Transition', 'Transition', 'Transition', 'Transition',
    'Transition', 'Transition', 'Transition to Tech Review 1',
    'Transition to Tech Review 2']

>>> descriptions = [item.description for item in pd.transitions if item.description]
>>> 'Use this transition if there are editorial changes required.' in descriptions
True

4.3.1 (2023-04-04)

• Moving CI to github actions

• Removed buildout support

• Added Python 3.10 and 3.11 support.

• Removed Python 2 support.

• Fixed Deadline / ExceptionName parsing.

4.3.0 (2022-04-07)

• evaluateInputs: refactored to handle most common exceptions.

• getInitialDataFieldsValues: new function to parse datafields initial values.

• drop Python 2 support.

4.2.2 (2019-09-06)

• Exposed deadline parsing as Activity.digestDeadlineDefinition

4.2.0 (2018-11-12)

• Add Python 3.7 support.

• Remove Python 3.5 support.

• Remvoe all deprecation and resource warnings.

4.1.1 (2018-02-08)

• More Python 3 compatibility.

4.1.0 (2018-02-06)

• Python 3 support.

4.0.4 (2017-11-01)

• Make the now function pluggable.

4.0.3 (2017-06-20)

• Nothing changed yet.

4.0.2 (2017-05-25)

• Update and improve Trove classifiers.

4.0.1 (2017-05-25)

• Fix small ReST issues, so that PyPI description will render.

4.0.0 (2017-05-25)

• Renamed from zope.wfmc to shoobx.wfmc.

• Added support for community CI and coverage tools.

• Raise an exception on duplicate ExtendedAttribute Name in a single ExtendedAttributes container

• Use IProcessDefinitionFactory to retrieve process definitions instead of named utilities. This additional layer of indirection allows to generate definitions dynamically.

• Support for synchronious and asynchronous execution of WFMC subflows. Subflows are executed as part of main process, however have their separate state (workflow variables).

• The simplistic Python evaluate(expr, locals) function has been replaced by the PythonExpressionEvaluator component, which is an adapter from IProcess to IPythonExpressionEvaluator. The evaluation locals namespace is automatically filled with workflow- and application-relevant data attributes, the context of the process and the passed in locals variable.

  All calls of evaluate() have been updated to use the adapter.

  This change allows for easy replacement of the evaluation engine to hook up a safe Python engine (i.e. RestrictedPython) and to provide more namespace entries.

• Transition conditions can now be evaluated in the larger context of a process, instead of just the workflow-relevant data. Thus their calling signature changed from condition(data) to condition(process, data).

• TextCondition has been changed to use the PythonExpressionEvaluator component. Also, the compile optimization has been removed, since the expression evalautor can do this more effectively.

• Support for aborting processes and activities.

  • Work items can be abortable by implementing IAbortWorkItem.

  • Work items can be cleaned up, if they implement ICleanupWorkItem.

  • Activities keep track of finished work items.

  • Activities can clean themselves up by cleaning up work items.

  • Processes keep track of finished activities.

  • When processes are aborted, the following is done:

    • All activities are aborted.

    • All finished activities are cleaned up.

      • isAborted flag is set on a process.

• Support for reading XPDL-2.1 added

• Added reading Pools and Lanes from XPDL

3.5.0 (2009-07-24)

• Update tests to latest package versions.

3.4.0 (2007-11-02)

• Initial release independent of the main Zope tree.