This endpoint lets you publish data to multiple consumers who are listening on a topic
.
Dapr guarantees At-Least-Once semantics for this endpoint.
POST http://localhost:<daprPort>/v1.0/publish/<pubsubname>/<topic>[?<metadata>]
Code | Description |
---|---|
204 | Message delivered |
403 | Message forbidden by access controls |
404 | No pubsub name or topic given |
500 | Delivery failed |
Parameter | Description |
---|---|
daprPort | The Dapr port |
pubsubname | The name of pubsub component |
topic | The name of the topic |
metadata | Query parameters for metadata as described below |
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"
}'
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 application/cloudevents+json
value for the Content-Type
header.
Metadata can be sent via query parameters in the request’s URL. It must be prefixed with metadata.
, as shown below.
Parameter | Description |
---|---|
metadata.ttlInSeconds | The number of seconds for the message to expire, as described here |
metadata.rawPayload | Boolean to determine if Dapr should publish the event without wrapping it as CloudEvent, as described here |
Additional metadata parameters are available based on each pubsub component.
This endpoint lets you publish multiple messages to consumers who are listening on a topic
.
POST http://localhost:<daprPort>/v1.0-alpha1/publish/bulk/<pubsubname>/<topic>[?<metadata>]
The request body should contain a JSON array of entries with:
If the content type for an event is not application/cloudevents+json
, it is auto-wrapped as a CloudEvent (unless metadata.rawPayload
is set to true
).
Example:
curl -X POST http://localhost:3500/v1.0-alpha1/publish/bulk/pubsubName/deathStarStatus \
-H 'Content-Type: application/json' \
-d '[
{
"entryId": "ae6bf7c6-4af2-11ed-b878-0242ac120002",
"event": "first text message",
"contentType": "text/plain"
},
{
"entryId": "b1f40bd6-4af2-11ed-b878-0242ac120002",
"event": {
"message": "second JSON message"
},
"contentType": "application/json"
},
]'
The Content-Type
header should always be set to application/json
since the request body is a JSON array.
Parameter | Description |
---|---|
daprPort | The Dapr port |
pubsubname | The name of pub/sub component |
topic | The name of the topic |
metadata | Query parameters for metadata |
Metadata can be sent via query parameters in the request’s URL. It must be prefixed with metadata.
, as shown in the table below.
Parameter | Description |
---|---|
metadata.rawPayload | Boolean to determine if Dapr should publish the messages without wrapping them as CloudEvent. |
metadata.maxBulkPubBytes | Maximum bytes to publish in a bulk publish request. |
HTTP Status | Description |
---|---|
204 | All messages delivered |
400 | Pub/sub does not exist |
403 | Forbidden by access controls |
500 | At least one message failed to be delivered |
In case of a 500 status code, the response body will contain a JSON object containing a list of entries that failed to be delivered. For example from our request above, if the entry with event "first text message"
failed to be delivered, the response would contain its entry ID and an error message from the underlying pub/sub component.
{
"failedEntries": [
{
"entryId": "ae6bf7c6-4af2-11ed-b878-0242ac120002",
"error": "some error message"
},
],
"errorCode": "ERR_PUBSUB_PUBLISH_MESSAGE"
}
Dapr will invoke the following endpoint on user code to discover topic subscriptions:
GET http://localhost:<appPort>/dapr/subscribe
Parameter | Description |
---|---|
appPort | The application port |
A JSON-encoded array of strings.
Example:
[
{
"pubsubname": "pubsub",
"topic": "newOrder",
"routes": {
"rules": [
{
"match": "event.type == order",
"path": "/orders"
}
]
"default" : "/otherorders"
},
"metadata": {
"rawPayload": "true"
}
}
]
Note, all subscription parameters are case-sensitive.
Optionally, metadata can be sent via the request body.
Parameter | Description |
---|---|
rawPayload | boolean to subscribe to events that do not comply with CloudEvent specification, as described here |
In order to deliver topic events, a POST
call will be made to user code with the route specified in the subscription response. Under routes
, you can provide rules that match a certain condition to a specific path when a message topic is received. You can also provide a default route for any rules that do not have a specific match.
The following example illustrates this point, considering a subscription for topic newOrder
with route orders
on port 3000: POST http://localhost:3000/orders
POST http://localhost:<appPort>/<path>
Note, all URL parameters are case-sensitive.
Parameter | Description |
---|---|
appPort | The application port |
path | Route path from the subscription configuration |
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>"
}
Status | Description |
---|---|
SUCCESS | Message is processed successfully |
RETRY | Message to be retried by Dapr |
DROP | Warning is logged and message is dropped |
Others | Error, message to be retried by Dapr |
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:
HTTP Status | Description |
---|---|
2xx | message is processed as per status in payload (SUCCESS if empty; ignored if invalid payload). |
404 | error is logged and message is dropped |
other | warning is logged and message to be retried |
This allows you to subscribe to multiple messages from a broker when listening to a topic
.
In order to receive messages in a bulk manner for a topic subscription, the application:
bulkSubscribe
while sending list of topics to be subscribed tomaxMessagesCount
and/or maxAwaitDurationMs
Refer to the Send and receive messages in bulk guide for more details on how to opt-in.An HTTP 2xx response denotes that entries (individual messages) inside this bulk message have been processed by the application and Dapr will now check each EntryId status. A JSON-encoded payload body with the processing status against each entry needs to be sent:
{
"statuses":
[
{
"entryId": "<entryId1>",
"status": "<status>"
},
{
"entryId": "<entryId2>",
"status": "<status>"
}
]
}
Note: If an EntryId status is not found by Dapr in a response received from the application, that entry’s status is considered
RETRY
.
Status | Description |
---|---|
SUCCESS | Message is processed successfully |
RETRY | Message to be retried by Dapr |
DROP | Warning is logged and message is dropped |
The HTTP response might be different from HTTP 2xx. The following are Dapr’s behavior in different HTTP statuses:
HTTP Status | Description |
---|---|
2xx | message is processed as per status in payload. |
404 | error is logged and all messages are dropped |
other | warning is logged and all messages to be retried |
Dapr pub/sub adheres to version 1.0 of CloudEvents.