Pub/sub API reference

This endpoint lets you publish data to multiple consumers who are listening on a . Dapr guarantees At-Least-Once semantics for this endpoint.

HTTP Response codes

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

Headers

The Content-Type header tells Dapr which content type your data adheres to when constructing a CloudEvent envelope. The Content-Type header value populates the datacontenttype field in the CloudEvent.

Unless specified, Dapr assumes text/plain. If your content type is JSON, use a Content-Type header with the value of application/json.

If you want to send your own custom CloudEvent, use the value for the Content-Type header.

Metadata

Metadata can be sent via query parameters in the request’s URL. It must be prefixed with metadata., as shown below.

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

HTTP Request

URL Parameters

HTTP Response body

A JSON-encoded array of strings.

Example:

[
  {
    "topic": "newOrder",
    "route": "/orders",
    "metadata": {
      "rawPayload": "true",
    }
  }
]

Metadata

Optionally, metadata can be sent via the request body.

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.

HTTP Request

URL Parameters

Expected HTTP Response

An HTTP 2xx response denotes successful processing of message.

For richer response handling, a JSON-encoded payload body with the processing status can be sent:

{
  "status": "<status>"
}

Dapr assumes that a JSON-encoded payload response without status field or an empty payload responses with HTTP 2xx is a SUCCESS.

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

Dapr pub/sub adheres to version 1.0 of CloudEvents.

• Sample for pub/sub