I'm a little confused by the serializers and message converters in spring-kafka. When should the Spring message converters be used and when only the Kafka serializers? As far as I could see in Spring the prefered way would be to configure the Kafka clients key/value serializer with StringSerializer
and then configure a message converter on the KafkaTemplate
for the actual POJO to string conversion. Is that correct?
I'm stuck trying to configure a DeadLetterPublishingRecoverer
which should send messages to DLT for derialization errors as well as for any error while processing the deserialized message. The problem is that I need a JsonSerializer
when the message was already deserialized but only a simple StringSerializer
when the message could not be deserialized. Any ideas how to configure that?
Message conversion in the template only applies to the send()
method that takes a Message<?>
.
Use one of the DLPR constructors that takes a map of templates:
/**
* Create an instance with the provided templates and a default destination resolving
* function that returns a TopicPartition based on the original topic (appended with
* ".DLT") from the failed record, and the same partition as the failed record.
* Therefore the dead-letter topic must have at least as many partitions as the
* original topic. The templates map keys are classes and the value the corresponding
* template to use for objects (producer record values) of that type. A
* {@link java.util.LinkedHashMap} is recommended when there is more than one
* template, to ensure the map is traversed in order. To send records with a null
* value, add a template with the {@link Void} class as a key; otherwise the first
* template from the map values iterator will be used.
* @param templates the {@link KafkaOperations}s to use for publishing.
*/
public DeadLetterPublishingRecoverer(Map<Class<?>, KafkaOperations<? extends Object, ? extends Object>> templates) {
this(templates, DEFAULT_DESTINATION_RESOLVER);
}
Add a template configured for byte[]
values (with a ByteArraySerializer
on its producer) for the deserialization exceptions.