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docs/reference/api/pubsub_api.md

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Pub Sub

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

Code Description
200 Message delivered
500 Delivery failed

URL Parameters

Parameter Description
daprPort the Dapr port
pubsubname the name of pubsub component.
topic the name of the topic 
curl -X POST http://localhost:3500/v1.0/publish/pubsubName/deathStarStatus \
  -H "Content-Type: application/json" \
 -d '{
       "status": "completed"
     }'

Required 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

Parameter Description
appPort the application port

HTTP Response body

A json encoded array of strings.

Example:

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

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:

HTTP Request

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

URL Parameters

Parameter Description
appPort the application port

HTTP Response body

A JSON encoded payload.

Message Envelope

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

Related links