Publishing & subscribing messages without CloudEvents

Learn when you might not use CloudEvents and how to disable them.

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.

Publishing raw messages

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

Diagram showing how to publish with Dapr when subscriber does not use Dapr or CloudEvent

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


curl -X "POST" http://localhost:3500/v1.0/publish/pubsub/TOPIC_A?metadata.rawPayload=true -H "Content-Type: application/json" -d '{"order-number": "345"}'


using Dapr.Client;

var builder = WebApplication.CreateBuilder(args);
builder.Services.AddControllers().AddDapr();

var app = builder.Build();

app.MapPost("/publish", async (DaprClient daprClient) =>
{
    var message = new Message(
        Guid.NewGuid().ToString(),
        $"Hello at {DateTime.UtcNow}",
        DateTime.UtcNow
    );

    await daprClient.PublishEventAsync(
        "pubsub",           // pubsub name
        "messages",         // topic name
        message,           // message data
        new Dictionary<string, string> 
        { 
            { "rawPayload", "true" },
            { "content-type", "application/json" }
        }
    );
    
    return Results.Ok(message);
});

app.Run();


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)


<?php

require_once __DIR__.'/vendor/autoload.php';

$app = \Dapr\App::create();
$app->run(function(\DI\FactoryInterface $factory) {
    $publisher = $factory->make(\Dapr\PubSub\Publish::class, ['pubsub' => 'pubsub']);
    $publisher->topic('TOPIC_A')->publish('data', ['rawPayload' => 'true']);
});

Subscribing to raw messages

Dapr apps are also able to subscribe to raw events coming from existing pub/sub topics that do not use CloudEvent encapsulation.

Diagram showing how to subscribe with Dapr when publisher does not use Dapr or CloudEvent

Programmatically subscribe to raw events

When subscribing programmatically, add the additional metadata entry for rawPayload to allow the subscriber to receive a message that is not wrapped by a CloudEvent. For .NET, this metadata entry is called isRawPayload.


using System.Text.Json;
using System.Text.Json.Serialization;

var builder = WebApplication.CreateBuilder(args);
var app = builder.Build();

app.MapGet("/dapr/subscribe", () =>
{
    var subscriptions = new[]
    {
        new
        {
            pubsubname = "pubsub",
            topic = "messages",
            route = "/messages",
            metadata = new Dictionary<string, string>
            {
                { "isRawPayload", "true" },
                { "content-type", "application/json" }
            }
        }
    };
    return Results.Ok(subscriptions);
});

app.MapPost("/messages", async (HttpContext context) =>
{
    using var reader = new StreamReader(context.Request.Body);
    var json = await reader.ReadToEndAsync();

    Console.WriteLine($"Raw message received: {json}");

    return Results.Ok();
});

app.Run();


import flask
from flask import request, jsonify
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',
                      } }]
    return jsonify(subscriptions)

@app.route('/dsstatus', methods=['POST'])
def ds_subscriber():
    print(request.json, flush=True)
    return json.dumps({'success':True}), 200, {'ContentType':'application/json'}

app.run()


<?php

require_once __DIR__.'/vendor/autoload.php';

$app = \Dapr\App::create(configure: fn(\DI\ContainerBuilder $builder) => $builder->addDefinitions(['dapr.subscriptions' => [
    new \Dapr\PubSub\Subscription(pubsubname: 'pubsub', topic: 'deathStarStatus', route: '/dsstatus', metadata: [ 'rawPayload' => 'true'] ),
]]));

$app->post('/dsstatus', function(
    #[\Dapr\Attributes\FromBody]
    \Dapr\PubSub\CloudEvent $cloudEvent,
    \Psr\Log\LoggerInterface $logger
    ) {
        $logger->alert('Received event: {event}', ['event' => $cloudEvent]);
        return ['status' => 'SUCCESS'];
    }
);

$app->start();

Declaratively subscribe to raw events

Similarly, you can subscribe to raw events declaratively by adding the rawPayload metadata entry to your subscription specification.

apiVersion: dapr.io/v2alpha1
kind: Subscription
metadata:
  name: myevent-subscription
spec:
  topic: deathStarStatus
  routes: 
    default: /dsstatus
  pubsubname: pubsub
  metadata:
    isRawPayload: "true"
scopes:
- app1
- app2

Next steps


Last modified February 15, 2025: Update deprecated exporter (#4543) (27683a6)