EO-Kafka with Spring

When building the microservices we need to use frameworks to bootstrap the project. Spring is one of them. We are not going to discuss here problems with Spring Framework in general. Instead, we will connect eo-kafka with Spring. Have fun!

Here we discuss how to use EO-Kafka and how it’s different from Spring Kafka starter. In this blog post I will show you how to integrate EO-Kafka into existing Spring Application.

1. Add a dependency

<dependency>
  <groupId>io.github.eo-cqrs</groupId>
  <artifactId>eo-kafka</artifactId>
  <version><!--get the latest from maven central--></version>
  <exclusions>
    <exclusion>
      <groupId>org.slf4j</groupId>
      <artifactId>slf4j-simple</artifactId>
    </exclusion>
  </exclusions>
</dependency>

2. Create config

You can create Beans using Parameters API:

@Configuration
public class KafkaConfig {

  @Bean
  public Producer<String, User> userProducer() {
    return new KfProducer<>(
      new KfFlexible<>(
        new KfProducerParams(
          new KfParams(
            new BootstrapServers("< bootstrap servers >"),
            new KeySerializer("org.apache.kafka.common.serialization.StringSerializer"),
            new ValueSerializer("< user serializer >")
          )
        )
      )
    );
  }

  @Bean
  public Consumer<String, User> consumer() {
    return new KfConsumer<>(
      new KfFlexible<>(
        new KfConsumerParams(
          new KfParams(
            new BootstrapServers("< bootstrap servers >"),
            new GroupId("1"),
            new KeyDeserializer("org.apache.kafka.common.serialization.StringDeserializer"),
            new ValueDeserializer("< user deserializer >")
          )
        )
      )
    );
  }
}

If you want to store all the information about the Producers and Consumers XML can help you:

@Configuration
public class KafkaConfig {

  @Bean
  public Producer<String, User> userProducer() throws Exception {
    return new KfProducer<>(
      new KfXmlFlexible<>(
        "userProducer.xml"
      )
    );
  }

  @Bean
  public Consumer<String, User> consumer() throws Exception {
    return new KfConsumer<>(
      new KfXmlFlexible<>(
        "userConsumer.xml"
      )
    );
  }
}

with following XML files: userProducer.xml

<producer>
  <bootstrapServers><!--bootstrap servers --></bootstrapServers>
  <keySerializer><!--key serializer--></keySerializer>
  <valueSerializer><!--user serializer--></valueSerializer>
  ...
</producer>

userConsumer.xml

<consumer>
  <bootstrapServers><!--bootstrap servers--></bootstrapServers>
  <groupId><!--group id--></groupId>
  <keyDeserializer><!--key deserializer--></keyDeserializer>
  <valueDeserializer><!--user deserializer--></valueDeserializer>
  ...
</consumer>

All parameters and it’s tags is here.

By the way your files structure should look life this:

src/
  main/
    java/
      foo/
        KafkaConfig.java
    resources/
        userConsumer.xml
        userProducer.xml

3. Use it!

Inject your Consumer and Producer and use it like I’m described here

If you have some ideas how we can improve the microservices architecture, please submit the issue, and we will provide you feedback.