This example utilizes a publisher and a subscriber to show the pubsub pattern, it also shows PublishEvent, PublishEvents (bulk), OnTopicEvent, GetTopicSubscriptions, and TopicEventResponse functionality. It creates a publisher and calls the publish_event and publish_events methods in the DaprClient. It will create a gRPC subscriber and bind the OnTopicEvent method, which gets triggered after a message is published to the subscribed topic. The subscriber will tell dapr to retry delivery of the first message it receives, logging that the message will be retried, and printing it at least once to standard output.

Note: Make sure to use the latest proto bindings

• Dapr CLI and initialized environment
• Install Python 3.10+

pip3 install dapr dapr-ext-grpc

Run the following command in a terminal/command prompt:

# 1. Start Subscriber (expose gRPC server receiver on port 50051)
dapr run --app-id python-subscriber --app-protocol grpc --app-port 50051 -- python3 subscriber.py

In another terminal/command prompt run:

# 2. Start Publisher
dapr run --app-id python-publisher --app-protocol grpc --dapr-grpc-port=3500 --enable-app-health-check -- python3 publisher.py

dapr stop --app-id python-subscriber