mirror of https://github.com/dapr/docs.git
89 lines
1.7 KiB
Markdown
89 lines
1.7 KiB
Markdown
# Pub Sub
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## Publish a message to a given topic
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This endpoint lets you publish a payload to multiple consumers who are listening on a ```topic```.
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Dapr guarantees at least once semantics for this endpoint.
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### HTTP Request
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```http
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POST http://localhost:<daprPort>/v1.0/publish/<topic>
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```
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### HTTP Response codes
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Code | Description
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---- | -----------
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200 | Message delivered
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500 | Delivery failed
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### URL Parameters
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Parameter | Description
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--------- | -----------
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daprPort | the Dapr port
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topic | the name of the topic
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```shell
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curl -X POST http://localhost:3500/v1.0/publish/deathStarStatus \
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-H "Content-Type: application/json" \
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-d '{
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"status": "completed"
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}'
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```
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# Required Application (User Code) Routes
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## Provide a route for Dapr to discover topic subscriptions
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Dapr will invoke the following endpoint on user code to discover topic subscriptions:
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### HTTP Request
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```http
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GET http://localhost:<appPort>/dapr/subscribe
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```
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### URL Parameters
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Parameter | Description
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--------- | -----------
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appPort | the application port
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### HTTP Response body
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A json encoded array of strings.
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Example:
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```json
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"["TopicA","TopicB"]"
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```
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## Provide route(s) for Dapr to deliver topic events
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In order to deliver topic events, a `POST` call will be made to user code with the name of the topic as the URL path.
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The following example illustrates this point, considering a subscription for topic `TopicA`:
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### HTTP Request
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```http
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POST http://localhost:<appPort>/TopicA
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```
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### URL Parameters
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Parameter | Description
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--------- | -----------
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appPort | the application port
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### HTTP Response body
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A JSON encoded payload.
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## Message Envelope
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Dapr Pub/Sub adheres to version 0.3 of Cloud Events.
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