In reference
to:
https://groups.google.com/forum/#!searchin/web2py/workflow/web2py/osEmmtu9hlg/2MHi_ZCeMBMJ
Has anyone done any work on this yet? I was thinking about making a
web2py-based workflow engine.
I mentioned previously that I built one of these for an application I wrote
several years ago, but it was built specifically for that app. This will be
my first attempt at making a general-use workflow engine, so let me know if
you find any problems with my design:
Make a contrib module that is initialized like the Auth module:
from gluon.contrib.workflow_engine import WorkflowEngine, Step
workflow_engine = WorkflowEngine()
workflow_engine.define_tables()
I will use the example that I know best, which is passing around a sales
order throughout a company's departments. This first example would define a
workflow template because every sales order will have the same workflow:
workflow_engine.add_template('Sales Order',
Step(group_id=2, hours=4), # Engineering gets 4 hours to complete their
step
Step(user_id=7, hours=0), # The engineering manager (user) has no time
limit
Step(group_id=3, hours=2), # Quality department gets 2 hours to inspect
the order
Step(group_id=8, hours=6.5), # Shipping department gets 6.5 hours to
ship order
)
You would start this workflow like this:
workflow_id = workflow_engine.load_template('Sales Order', item_type=
'document', item_id=1)
workflow_id = workflow_engine.
workflow_engine.start(workflow_id)
Optionally, a workflow can be created on the fly (if the workflow will only
be used once):
workflow_id = workflow_engine.create_workflow('One-time Workflow',
'document', 1 # same as item_type and item_id used in load_template()
Step(group_id=2, hours=4)
Step(group_id=3, due_date=request.now + datetime.timedelta(days=1)) #
set time limit to an exact datetime
)
workflow_engine.start(workflow_id) # start the workflow we just created
We assume that we are going to associate this workflow with another object.
In this case, we will assume there is a table called "document" and that
the document we want to pass around has an id of 1. The "item_type"
argument allows you to pass around any type of database object. In this
case, we will call it the same thing as our table: "document".
These are some common operations that could be done:
workflow_engine.active_workflows() # returns a list of all active workflows
workflow_engine.active_workflows(user_id=1) # all active workflows for the
user_id
workflow_engine.active_workflows(user_id=1, include_groups=True) # same as
above, but includes groups the user is a member of
workflow_engine.active_workflows(group_id=2) # all active workflows for the
group_id
workflow_engine.late_workflows() # returns a list of all late/overdue
workflows
workflow_engine.step_complete(workflow_id, notes='General info about
completed task') # moves workflow to the next step
workflow_engine.step_reject(workflow_id, to_step=2, notes='Why step was
rejected') # moves workflow back to step 2 incase there was a problem with
one of the previously completed steps
Workflow triggers:
workflow_engine.before_start = function(workflow, step)
workflow_engine.after_start = function(workflow, step)
workflow_engine.before_step_complete = function(workflow, step)
workflow_engine.after_step_complete = function(workflow, step)
workflow_engine.before_step_reject = function(workflow, step)
workflow_engine.after_step_reject = function(workflow, step)
workflow_engine.before_finish = function(workflow, step)
workflow_engine.after_finish = function(workflow, step)
Finally, (and I MIGHT do this) since we are using time limits in hours, we
should set some time ranges where users are available. For example, if the
company is only open from 8 AM to 5 PM, you wouldn't want something to be
late at 7 PM. You would want to roll over the extra 2 hours so that it
becomes late at 10 AM the next business day. A list of time ranges would be
created, and a user would be assigned to one of the time ranges. This would
accommodate users in different time zones or with different "work" hours.
Again, this last part I MIGHT do if I have enough time. I've done it
before, but I'm sure you can imagine how complicated this part is.
So any questions, comments, improvements? Thanks!
