Package com.hivemq.extensions.kafka.api.transformers.kafkatomqtt

Interface KafkaToMqttTransformer

All Superinterfaces:

Transformer<KafkaToMqttInitInput>

Functional Interface:

This is a functional interface and can therefore be used as the assignment target for a lambda expression or method reference.

@FunctionalInterface
public interface KafkaToMqttTransformer
extends Transformer<KafkaToMqttInitInput>

Implement this transformer for the programmatic creation of Publishes from KafkaRecords. One instance of the implementing class is created per reference in the kafka-configuration.xml. The methods of this interface may be called concurrently and must be thread-safe.

Your implementation of the KafkaToMqttTransformer must be placed in a Java archive (.jar) together with all its dependencies in the customizations folder of the "HiveMQ Enterprise Extension for Kafka". In addition, a <kafka-to-mqtt-transformer> referencing the implementing class via its canonical name must be configured in the kafka-extension.xml file.

Since:

4.5.0

Method Summary

Modifier and Type	Method	Description
void	transformKafkaToMqtt(@NotNull KafkaToMqttInput input, @NotNull KafkaToMqttOutput output)	This callback is executed for every KafkaRecord that the "HiveMQ Enterprise Extension for Kafka" polls from Kafka according to the configured <kafka-topics> in the <kafka-to-mqtt-transformer> tag.

Methods inherited from interface com.hivemq.extensions.kafka.api.transformers.Transformer

init

Method Detail

transformKafkaToMqtt

@ThreadSafe
void transformKafkaToMqtt(@NotNull
                          @NotNull KafkaToMqttInput input,
                          @NotNull
                          @NotNull KafkaToMqttOutput output)

This callback is executed for every KafkaRecord that the "HiveMQ Enterprise Extension for Kafka" polls from Kafka according to the configured <kafka-topics> in the <kafka-to-mqtt-transformer> tag.

It allows the publication of any number of Publishes via the KafkaToMqttOutput object. This method is called by multiple threads concurrently. Extensions are responsible for their own exception handling and this method must not throw any Exception.

Parameters:

input - The KafkaToMqttInput contains the triggering KafkaRecord and the KafkaCluster information.

output - The KafkaToMqttOutput allows to provide a list of Publishes. If no output is set, an empty List is used as default and the kafka record will not be processed again, but ignored.

Since:

4.5.0