Publishing & subscribing messages without CloudEvents

When adding Dapr to your application, some services may still need to communicate via pub/sub messages not encapsulated in CloudEvents, due to either compatibility reasons or some apps not using Dapr. These are referred to as “raw” pub/sub messages. Dapr enables apps to publish and subscribe to raw events not wrapped in a CloudEvent for compatibility.

Dapr apps are able to publish raw events to pub/sub topics without CloudEvent encapsulation, for compatibility with non-Dapr apps.

Warning

Not using CloudEvents disables support for tracing, event deduplication per messageId, content-type metadata, and any other features built using the CloudEvent schema.

To disable CloudEvent wrapping, set the metadata to true as part of the publishing request. This allows subscribers to receive these messages without having to parse the CloudEvent schema.

• curl
• PHP SDK

from dapr.clients import DaprClient
with DaprClient() as d:
    req_data = {
        'order-number': '345'
    }
    # Create a typed message with content type and body
    resp = d.publish_event(
        pubsub_name='pubsub',
        topic_name='TOPIC_A',
        data=json.dumps(req_data),
        publish_metadata={'rawPayload': 'true'}
    # Print the request
    print(req_data, flush=True)

When subscribing programmatically, add the additional metadata entry for rawPayload so the Dapr sidecar automatically wraps the payloads into a CloudEvent that is compatible with current Dapr SDKs.

• PHP SDK

import flask
from flask_cors import CORS
import json
import sys
app = flask.Flask(__name__)
CORS(app)
@app.route('/dapr/subscribe', methods=['GET'])
def subscribe():
    subscriptions = [{'pubsubname': 'pubsub',
                      'topic': 'deathStarStatus',
                      'route': 'dsstatus',
                      'metadata': {
                          'rawPayload': 'true',
                      } }]
@app.route('/dsstatus', methods=['POST'])
    print(request.json, flush=True)
    return json.dumps({'success':True}), 200, {'ContentType':'application/json'}
app.run()

apiVersion: dapr.io/v1alpha1
kind: Subscription
metadata:
  name: myevent-subscription
spec:
  topic: deathStarStatus
  route: /dsstatus
  pubsubname: pubsub
  metadata:
    rawPayload: "true"
scopes:
- app1
- app2

• Learn more about
• Read the API reference