Pub/sub API reference

Detailed documentation on the pub/sub API

Publish a message to a given topic

This endpoint lets you publish data to multiple consumers who are listening on a topic. Dapr guarantees at least once semantics for this endpoint.

HTTP Request

POST http://localhost:<daprPort>/v1.0/publish/<pubsubname>/<topic>

HTTP Response codes

URL Parameters

Note, all URL parameters are case-sensitive.

curl -X POST http://localhost:3500/v1.0/publish/pubsubName/deathStarStatus \
  -H "Content-Type: application/json" \
 -d '{
       "status": "completed"
     }'

Optional Application (User Code) Routes

Provide a route for Dapr to discover topic subscriptions

Dapr will invoke the following endpoint on user code to discover topic subscriptions:

HTTP Request

GET http://localhost:<appPort>/dapr/subscribe

URL Parameters

HTTP Response body

A json encoded array of strings.

Example:

[
  {
    "pubsubname": "pubsub",
    "topic": "newOrder",
    "route": "/orders"
  }
]

Note, all subscription parameters are case-sensitive.

Provide route(s) for Dapr to deliver topic events

In order to deliver topic events, a POST call will be made to user code with the route specified in the subscription response.

The following example illustrates this point, considering a subscription for topic newOrder with route orders on port 3000: POST http://localhost:3000/orders

HTTP Request

POST http://localhost:<appPort>/<path>

Note, all URL parameters are case-sensitive.

URL Parameters

Expected HTTP Response

An HTTP 200 response with JSON encoded payload body with the processing status:

{
  "status": "<status>"
}

For empty payload responses in HTTP 2xx, Dapr assumes SUCCESS.

The HTTP response might be different from HTTP 2xx, the following are Dapr’s behavior in different HTTP statuses:

Message envelope

Dapr Pub/Sub adheres to version 1.0 of Cloud Events.

Related links

• How to publish to and consume topics
• Sample for pub/sub

Last modified February 16, 2021: Merge pull request #1235 from dapr/update-v0.11 (b4e9fbb)