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add list of components that support consumerid 

Signed-off-by: Hannah Hunter <hannahhunter@microsoft.com>
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Hannah Hunter 2023-07-26 15:42:11 -04:00
parent a641eaa6c1
commit e58ba2ff7b
1 changed files with 9 additions and 4 deletions
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daprdocs/content/en/developing-applications/building-blocks/pubsub/pubsub-overview.md
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@ -102,16 +102,14 @@ Dapr solves multi-tenancy at-scale with [namespaces for consumer groups]({{< ref
Dapr guarantees at-least-once semantics for message delivery. When an application publishes a message to a topic using the pub/sub API, Dapr ensures the message is delivered *at least once* to every subscriber. Dapr guarantees at-least-once semantics for message delivery. When an application publishes a message to a topic using the pub/sub API, Dapr ensures the message is delivered *at least once* to every subscriber.
> **Note:** All Dapr pub/sub components support the at-least-once guarantee.
Even if the message fails to deliver, or your application crashes, Dapr attempts to redeliver the message until successful delivery. Even if the message fails to deliver, or your application crashes, Dapr attempts to redeliver the message until successful delivery.
All Dapr pub/sub components support the at-least-once guarantee.
### Consumer groups and competing consumers pattern ### Consumer groups and competing consumers pattern
Dapr handles the burden of dealing with consumer groups and the competing consumers pattern. In the competing consumers pattern, multiple application instances using a single consumer group compete for the message. Dapr enforces the competing conusmer pattern when replicas use the same `app-id` without explict consumer group overrides. Dapr handles the burden of dealing with consumer groups and the competing consumers pattern. In the competing consumers pattern, multiple application instances using a single consumer group compete for the message. Dapr enforces the competing conusmer pattern when replicas use the same `app-id` without explict consumer group overrides.
> **Note:** Not all Dapr pub/sub components support the competing consumer model.
When multiple instances of the same application (with same `app-id`) subscribe to a topic, Dapr delivers each message to *only one instance of **that** application*. This concept is illustrated in the diagram below. When multiple instances of the same application (with same `app-id`) subscribe to a topic, Dapr delivers each message to *only one instance of **that** application*. This concept is illustrated in the diagram below.
<img src="/images/pubsub-overview-pattern-competing-consumers.png" width=1000> <img src="/images/pubsub-overview-pattern-competing-consumers.png" width=1000>
@ -119,6 +117,13 @@ When multiple instances of the same application (with same `app-id`) subscribe t
Similarly, if two different applications (with different `app-id`) subscribe to the same topic, Dapr delivers each message to *only one instance of **each** application*. Similarly, if two different applications (with different `app-id`) subscribe to the same topic, Dapr delivers each message to *only one instance of **each** application*.
Not all Dapr pub/sub components support the competing consumer model. Currently, the following pub/sub components support this pattern:
- [Apache Kafka]({{< ref setup-apache-kafka >}})
- [Azure Service Bus Queues]({{< ref setup-azure-servicebus-queues >}})
- [RabbitMQ]({{< ref setup-rabbitmq >}})
- [Redis Streams]({{< ref setup-redis-pubsub >}})
### Scoping topics for added security ### Scoping topics for added security
By default, all topic messages associated with an instance of a pub/sub component are available to every application configured with that component. You can limit which application can publish or subscribe to topics with Dapr topic scoping. For more information, read: [pub/sub topic scoping]({{< ref pubsub-scopes.md >}}). By default, all topic messages associated with an instance of a pub/sub component are available to every application configured with that component. You can limit which application can publish or subscribe to topics with Dapr topic scoping. For more information, read: [pub/sub topic scoping]({{< ref pubsub-scopes.md >}}).