Skip to content

[Doc]--add retry letter topic to messaging docs. #7151

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Closed
Huanli-Meng wants to merge 1 commit into from
Closed

[Doc]--add retry letter topic to messaging docs. #7151

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
23 changes: 23 additions & 0 deletions site2/docs/concepts-messaging.md
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -160,6 +160,29 @@ Dead letter topic depends on message re-delivery. Messages are redelivered eithe
> Note
> Currently, dead letter topic is enabled only in the shared subscription mode.

### Retry letter topic

For many online business systems, a message needs to be re-consumed because any exception occurs in the business logic processing. Generally, users hope that they can flexibly configure the delay time for re-consuming the failed messages. In this case, you can configure the producer to send messages to both the business topic and the retry letter topic and you can enable automatic retry on the consumer. When automatic retry is enabled on the consumer, a message is stored in the retry letter topic if the messages fail to be consumed and therefore the consumer can automatically consume failed messages from the retry letter topic after a specified delay time.

By default, automatic retry is disabled. You can set `enableRetry` to `true` to enable automatic retry on the consumer.

This example shows how to consumer messages from a retry letter topic.

```java
Consumer<byte[]> consumer = pulsarClient.newConsumer(Schema.BYTES)
.topic(topic)
.subscriptionName("my-subscription")
.subscriptionType(SubscriptionType.Shared)
.enableRetry(true)
.receiverQueueSize(100)
.deadLetterPolicy(DeadLetterPolicy.builder()
.maxRedeliverCount(maxRedeliveryCount)
.retryLetterTopic("persistent://my-property/my-ns/my-subscription-custom-Retry")
.build())
.subscriptionInitialPosition(SubscriptionInitialPosition.Earliest)
.subscribe();
```

## Topics

As in other pub-sub systems, topics in Pulsar are named channels for transmitting messages from [producers](reference-terminology.md#producer) to [consumers](reference-terminology.md#consumer). Topic names are URLs that have a well-defined structure:
Expand Down