Hello world

This script demonstrates how to define an Ewoks workflow from the ground up. The only thing needed to run it is the ewoks Python package

pip install ewoks

The script defines defines two tasks, one that ask for a name and the other that creates a greeting, creates a workflow out of these and executes it.

from ewokscore import Task
from ewoks import execute_graph


# Define a workflow task with an output
class AskForName(Task, output_names=["input_name"]):
    def run(self):
        name = input("What is your name?")
        if not name:
            name = "World"
        self.outputs.input_name = name


# Define a workflow task with inputs and outputs
class SayHello(
    Task,
    input_names=["name"],
    optional_input_names=["in_french"],
    output_names=["greeting"],
):
    def run(self):
        name = self.inputs.name
        if self.inputs.in_french:
            hello = "Bonjour"
        else:
            hello = "Hello"
        self.outputs.greeting = f"{hello}, {name}!"


# Define nodes: entities that will execute tasks
nodes = [
    {
        "id": "ask_for_name",
        "task_type": "class",
        "task_identifier": "__main__.AskForName",
    },
    {
        "id": "say_hello",
        "task_type": "class",
        "task_identifier": "__main__.SayHello",
    },
]
# Define links that make data flow from one node to another
links = [
    {
        "source": "ask_for_name",
        "target": "say_hello",
        "data_mapping": [{"source_output": "input_name", "target_input": "name"}],
    }
]
# Define a workflow from nodes, links and graph metadata
workflow = {"graph": {"id": "hello_world"}, "nodes": nodes, "links": links}


# Execute a workflow
result = execute_graph(workflow)
print(result)
print('----')

# Optionally, define inputs
inputs = [{"id": "say_hello", "name": "in_french", "value": True}]

# Execute a workflow with inputs
result = execute_graph(workflow, inputs=inputs)
print(result)

This is the output you should get

$ python hello_world.py
What is your name? Ewoks # <--- `input` waits for some input. `Ewoks` was typed here and Enter pressed.
{'greeting': 'Hello, Ewoks!'}
----
What is your name?  # <--- Enter was pressed without typing anything
{'greeting': 'Bonjour, World!'}

Note

Ewoks developers rarely design workflows by hand like this but instead use graphical interfaces to produce the dictionnary (usually stored in JSON). See this page about the Ewoks graphical interfaces.

Note

For all the fields that can be set when creating the dictionnary representing the workflow, see the Ewoks specification.