Creating a workflow

In this section we’ll see how to create new workflows through an example, “Organizing a conference”:

First the call for papers is sent, and begins the search for a location. When there are sufficient talks and the location is chosen begins the propaganda. Then subscriptions are accounted until the starting day comes, when the conference finally begins.

The graph could be something like this:

digraph conference { "Send the Call for Papers" -> "Collect papers" "Collect papers" -> "Publicize" "Search a location" -> "Publicize" "Publicize" -> "Mailing" "Publicize" -> "Newspapers" "Publicize" -> "Poster" "Mailing" -> "Receive subscriptions" "Newspapers" -> "Receive subscriptions" "Poster" -> "Receive subscriptions" "Receive subscriptions" -> "Wait until the starting day" "Wait until the starting day" -> "Receive subscriptions" "Wait until the starting day" -> "Start the conference" };

Using django admin interface

We’ll see how to create the “Organizing a conference” workflow using Django’s admin interface:

../_images/ws-admin.png

Create the workflow

The new workflow’s only required attribute is name: “Organizing conference”

Node
  • name: “Send the Call for Papers”
  • is start: True
  • split: AND
  • role: Organization
  • celery task: conferencer.tasks.mailing
Node
  • name: “Collect papers”
  • join: AND
  • split: AND
  • role: Accounting
  • celery task: conferencer.tasks.ask_human
Node
  • name: “Publicize”
  • join: AND
  • split: AND
  • role: Accounting
  • celery task: conferencer.tasks.ask_human

Using fixtures

Using python

Create the workflow:

from ws.models import Workflow, Node, Transition, Process
from ws.tasks.dummy import dummy

# Create a workflow and save it
workflow = Workflow.objects.create()

# Create three nodes for the workflow tied to dummy tasks and save them
first = Node.objects.create(name='first', workflow=workflow, celery_task=dummy, is_start=True)
second = Node.objects.create(name='second', workflow=workflow, celery_task=dummy)
third = Node.objects.create(name='third', workflow=workflow, celery_task=dummy, is_end=True)

# Create two transitions to bind the nodes
Transition.objects.create(parent=first, child=second)
Transition.objects.create(parent=second, child=third)

Execute the workflow:

process = Process.objects.create(workflow=workflow)
process.start()