java-tutorials/spring-kafka/README.md

## Spring Kafka

This module contains articles about Spring with Kafka

### Relevant articles

- [Intro to Apache Kafka with Spring](https://www.baeldung.com/spring-kafka)
- [Testing Kafka and Spring Boot](https://www.baeldung.com/spring-boot-kafka-testing)

### Intro

This is a simple Spring Boot app to demonstrate sending and receiving of messages in Kafka using spring-kafka.

As Kafka topics are not created automatically by default, this application requires that you create the following topics manually.

`$ bin/kafka-topics.sh --create --zookeeper localhost:2181 --replication-factor 1 --partitions 1 --topic baeldung`<br>
`$ bin/kafka-topics.sh --create --zookeeper localhost:2181 --replication-factor 1 --partitions 5 --topic partitioned`<br>
`$ bin/kafka-topics.sh --create --zookeeper localhost:2181 --replication-factor 1 --partitions 1 --topic filtered`<br>
`$ bin/kafka-topics.sh --create --zookeeper localhost:2181 --replication-factor 1 --partitions 1 --topic greeting`<br>

When the application runs successfully, following output is logged on to console (along with spring logs):

#### Message received from the 'baeldung' topic by the basic listeners with groups foo and bar
>Received Message in group 'foo': Hello, World!<br>
Received Message in group 'bar': Hello, World!

#### Message received from the 'baeldung' topic, with the partition info
>Received Message: Hello, World! from partition: 0

#### Message received from the 'partitioned' topic, only from specific partitions
>Received Message: Hello To Partioned Topic! from partition: 0<br>
Received Message: Hello To Partioned Topic! from partition: 3

#### Message received from the 'filtered' topic after filtering
>Received Message in filtered listener: Hello Baeldung!

#### Message (Serialized Java Object) received from the 'greeting' topic
>Received greeting message: Greetings, World!!