Eventuate Binder for Spring Cloud Stream

The Eventuate Binder for Spring Cloud Stream enables a Spring Cloud Stream application to consume events from the Eventuate event store. Eventuate is a platform for simplifying the development of transactional microservices. It works in conjunction with frameworks such as Spring Boot to provide a programming model that is based on event sourcing and CQRS. You can try the SaaS version of Eventuate for free by signing up here.

Using the Eventuate Binder

Consider, for example, this simple Spring Cloud Stream application. It consumes messages from a stream and prints them.

@SpringBootApplication
@EnableBinding(Sink.class)
public class EventuateStreamDemoApplication {

  public static void main(String[] args) {
    SpringApplication.run(EventuateStreamDemoApplication.class, args);
  }

  @Bean
  public ExampleMessageConsumer exampleMessageConsumer() {
    return new ExampleMessageConsumer();
  }

}

public class ExampleMessageConsumer {

  @StreamListener(Sink.INPUT)
  public void handleMessage(Message<String> message) {
    System.out.println("Got message: " + message);
  }
}

To consume events published by Eventuate you do need to the following.

Configure Maven/Gradle dependencies

Maven:

<repositories>
  <repository>
      <id>eventuate-release</id>
      <url>http://mavenrepo.eventuate.io/release</url>
      <snapshots>
          <enabled>false</enabled>
      </snapshots>
  </repository>
</repositories>

<dependency>
  <groupId>io.eventuate.client.spring.cloud.stream</groupId>
  <artifactId>eventuate-client-spring-cloud-stream</artifactId>
  <version>0.1.0.RELEASE</version>
</dependency>
<dependency>
  <groupId>io.eventuate.client.java</groupId>
  <artifactId>eventuate-client-java-http-stomp-spring</artifactId>
  <version>0.1/version>
</dependency>

Gradle:

repositories {
    ...
    maven { url "http://mavenrepo.eventuate.io/release" }
}
...
dependencies {
  ...
  compile "io.eventuate.client.spring.cloud.stream:eventuate-client-spring-cloud-stream:0.1.0.RELEASE"
  compile "io.eventuate.client.java:eventuate-client-java-http-stomp-spring:0.1"
}

Configure the Eventuate client

In order for the Eventuate client to connect to the Eventuate event store you need to configure the following properties: eventuate.api.key.id, eventuate.api.key.secret. These are the credentials that you received when you signed up for Eventuate.

You can supply these properties using the usual Spring Boot mechanism. e.g. in an application.properties file or by setting environment variables.

Configure the Spring Cloud Stream Eventuate Consume

Since the example application shown above reads from a consumer called input, we need to configure a consumer with this name. The Eventuate Binder has a property called aggregatesAndEvents, which is a map from entity type to a set of event names. Here is an example configuration that consumes events published by the Account aggregate for the Money Transfer application

  eventuate.spring.cloud.stream.bindings.input.consumer.\
    aggregatesAndEvents[net.chrisrichardson.eventstore.javaexamples.banking.backend.commandside.accounts.Account]=\
    net.chrisrichardson.eventstore.javaexamples.banking.backend.common.accounts.AccountOpenedEvent,\ net.chrisrichardson.eventstore.javaexamples.banking.backend.common.accounts.AccountDebitedEvent,\
     net.chrisrichardson.eventstore.javaexamples.banking.backend.common.accounts.AccountCreditedEvent

Example application

Here is a simple example application.