This example demonstrates the use Kafka Outbound Channel Adapter and Message-Driven Channel Adapter.
It uses Java configuration for the adapters.
Start Apache Zookeeper and Apache Kafka according to the documentation for the Apache Kafka project.
$ gradlew :kafka:run
This will package the application and run it using the Gradle Application Plugin
In STS (Eclipse), go to package org.springframework.integration.samples.kafka, right-click Application and select Run as --> Java Application (or Spring Boot Application).
The application sends 10 messages (foo0 ... foo9) to a kafka topic si.topic; this must exist or the broker must be configured to auto-create topics.
It then sends a message with a KafkaNull payload.
It then dynamically creates a new inbound adapter for a different topic si.new.topic and sends 10 messages there.
The message-driven adapter receives the messages and places them in a QueueChannel which the application reads and
writes to stdout:
Sending 10 messages...
Sending a null message...
GenericMessage [payload=foo0, headers={kafka_offset=857, kafka_receivedMessageKey=si.key, kafka_receivedPartitionId=0, kafka_receivedTopic=si.topic}]
GenericMessage [payload=foo1, headers={kafka_offset=858, kafka_receivedMessageKey=si.key, kafka_receivedPartitionId=0, kafka_receivedTopic=si.topic}]
GenericMessage [payload=foo2, headers={kafka_offset=859, kafka_receivedMessageKey=si.key, kafka_receivedPartitionId=0, kafka_receivedTopic=si.topic}]
GenericMessage [payload=foo3, headers={kafka_offset=860, kafka_receivedMessageKey=si.key, kafka_receivedPartitionId=0, kafka_receivedTopic=si.topic}]
GenericMessage [payload=foo4, headers={kafka_offset=861, kafka_receivedMessageKey=si.key, kafka_receivedPartitionId=0, kafka_receivedTopic=si.topic}]
GenericMessage [payload=foo5, headers={kafka_offset=862, kafka_receivedMessageKey=si.key, kafka_receivedPartitionId=0, kafka_receivedTopic=si.topic}]
GenericMessage [payload=foo6, headers={kafka_offset=863, kafka_receivedMessageKey=si.key, kafka_receivedPartitionId=0, kafka_receivedTopic=si.topic}]
GenericMessage [payload=foo7, headers={kafka_offset=864, kafka_receivedMessageKey=si.key, kafka_receivedPartitionId=0, kafka_receivedTopic=si.topic}]
GenericMessage [payload=foo8, headers={kafka_offset=865, kafka_receivedMessageKey=si.key, kafka_receivedPartitionId=0, kafka_receivedTopic=si.topic}]
GenericMessage [payload=foo9, headers={kafka_offset=866, kafka_receivedMessageKey=si.key, kafka_receivedPartitionId=0, kafka_receivedTopic=si.topic}]
GenericMessage [payload=org.springframework.kafka.support.KafkaNull@3546d80f, headers={kafka_offset=867, kafka_receivedMessageKey=si.key, kafka_receivedPartitionId=0, kafka_receivedTopic=si.topic}]
Adding an adapter for a second topic and sending 10 messages...
GenericMessage [payload=bar0, headers={kafka_offset=200, kafka_receivedMessageKey=si.key, kafka_receivedPartitionId=0, kafka_receivedTopic=si.new.topic}]
GenericMessage [payload=bar1, headers={kafka_offset=201, kafka_receivedMessageKey=si.key, kafka_receivedPartitionId=0, kafka_receivedTopic=si.new.topic}]
GenericMessage [payload=bar2, headers={kafka_offset=202, kafka_receivedMessageKey=si.key, kafka_receivedPartitionId=0, kafka_receivedTopic=si.new.topic}]
GenericMessage [payload=bar3, headers={kafka_offset=203, kafka_receivedMessageKey=si.key, kafka_receivedPartitionId=0, kafka_receivedTopic=si.new.topic}]
GenericMessage [payload=bar4, headers={kafka_offset=204, kafka_receivedMessageKey=si.key, kafka_receivedPartitionId=0, kafka_receivedTopic=si.new.topic}]
GenericMessage [payload=bar5, headers={kafka_offset=205, kafka_receivedMessageKey=si.key, kafka_receivedPartitionId=0, kafka_receivedTopic=si.new.topic}]
GenericMessage [payload=bar6, headers={kafka_offset=206, kafka_receivedMessageKey=si.key, kafka_receivedPartitionId=0, kafka_receivedTopic=si.new.topic}]
GenericMessage [payload=bar7, headers={kafka_offset=207, kafka_receivedMessageKey=si.key, kafka_receivedPartitionId=0, kafka_receivedTopic=si.new.topic}]
GenericMessage [payload=bar8, headers={kafka_offset=208, kafka_receivedMessageKey=si.key, kafka_receivedPartitionId=0, kafka_receivedTopic=si.new.topic}]
GenericMessage [payload=bar9, headers={kafka_offset=209, kafka_receivedMessageKey=si.key, kafka_receivedPartitionId=0, kafka_receivedTopic=si.new.topic}]
Notice that the offset header increases on each run (the topic is not removed, to demonstrate that the offset is retained between executions).