Sonataflow implemented the ability to call a workflow as an action in another workflow.
We would like to understand in depth how this work. 

For example,

1. is it one instance for the parent workflow and sub workflows?
2. Can you trigger the sub workflow using an API?
3. Can the sub workflow access the parent workflow variables while it's running and get the updated information in real time?

The best way to understand this would be to run these workflow examples on a setup with a dataindex

https://github.com/kiegroup/kogito-serverless-operator/blob/main/test/e2e/testdata/order-processing/05_sonataflow.org_v1alpha08_sonataflow_devmode_orderprocessing.yaml

https://github.com/apache/incubator-kie-kogito-examples/blob/main/serverless-workflow-examples/serverless-workflow-subflows-event/src/main/resources/master.sw.json