dora/docs/src/python-api.md

• Python API
• • Operator
  • • Try it out!
  • Custom Node
  • • • Node()
      • .next() or __next__() as an iterator
      • .send_output(output_id, data)
    • Try it out!

Python API

Operator

The operator API is a framework for you to implement. The implemented operator will be managed by dora. This framework enable us to make optimisation and provide advanced features. It is the recommended way of using dora.

An operator requires an on_event method and requires to return a DoraStatus , depending of it needs to continue or stop.

{{#include ../../examples/python-operator-dataflow/object_detection.py:0:25}}

For Python, we recommend to allocate the operator on a single runtime. A runtime will share the same GIL with several operators making those operators run almost sequentially. See: https://docs.rs/pyo3/latest/pyo3/marker/struct.Python.html#deadlocks

Try it out!

• Create an operator python file called object_detection.py:

{{#include ../../examples/python-dataflow/object_detection.py}}

• Link it in your graph as:

{{#include ../../examples/python-dataflow/dataflow.yml:14:20}}

Custom Node

The custom node API allow you to integrate dora into your application. It allows you to retrieve input and send output in any fashion you want.

Node()

Node() initiate a node from environment variables set by dora-coordinator

from dora import Node

node = Node()

.next() or __next__() as an iterator

.next() gives you the next input that the node has received. It blocks until the next input becomes available. It will return None when all senders has been dropped.

input_id, value, metadata = node.next()

# or

for input_id, value, metadata in node:

.send_output(output_id, data)

send_output send data from the node.

node.send_output("string", b"string", {"open_telemetry_context": "7632e76"})

Try it out!

• Install python node API:

pip install dora-rs

• Create a python file called webcam.py:

{{#include ../../examples/python-dataflow/webcam.py}}

• Link it in your graph as:

{{#include ../../examples/python-dataflow/dataflow.yml:6:12}}