Spring Cloud Stream

Spring Cloud Stream is a framework for building message-driven microservices. Spring Cloud Stream builds upon Spring Boot to create DevOps friendly microservice applications and Spring Integration to provide connectivity to message brokers. Spring Cloud Stream provides an opinionated configuration of message brokers, introducing the concepts of persistent pub/sub semantics, consumer groups and partitions across several middleware vendors. This opinionated configuration provides the basis to create stream processing applications.

By adding @EnableBinding to your main application, you get immediate connectivity to a message broker and by adding @StreamListener to a method, you will receive events for stream processing.

Quick Start
Fork me on GitHub

Quick Start

Download

The recommended way to get started using spring-cloud-stream in your project is with a dependency management system – the snippet below can be copied and pasted into your build. Need help? See our getting started guides on building with Maven and Gradle.

As long as Spring Cloud Stream and a Spring Cloud Stream Binder dependencies are on the classpath any Spring Boot application with @EnableBinding will bind to the external message broker (e.g. Rabbit MQ or Apache Kafka, depending on the binder-implementation of choice).

Let's see it in action!

Head over to http://start.spring.io and create a project with the 'Stream Kafka' dependency. Modify the main class as shown below:

@SpringBootApplication
@EnableBinding(Source.class)
public class StreamdemoApplication {

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

    @Bean
    @InboundChannelAdapter(value = Source.OUTPUT)
    public MessageSource<String> timerMessageSource() {
        return () -> new GenericMessage<>(new SimpleDateFormat().format(new Date()));
    }

}

Make sure Kafka (0.10.1.x or later) is running when you run the application. You can use the kafka-console-consumer.sh utility provided by Kafka to monitor messages sent on the output topic.

Kafka Client Compatibility

Spring Cloud Stream's Kafka binder builds upon Spring Kafka and Spring Integration Kafka libraries. Specifically, Spring Kafka is the core to this foundation, and it is based on the pure java kafka-clients jar.

The following is the compatibility matrix of Spring cloud Stream and its dependent projects:

Spring Cloud Stream Version Spring for Apache Kafka Version Spring Integration for Apache Kafka Version kafka-clients Version
2.0.x 2.1.x, 2.0.x 3.0.x 1.0.x, 0.11.0.x*
1.3.x 1.3.x, 1.2.x, 1.1.x 2.3.x, 2.2.x, 2.1.x 0.11.0.x**, 0.10.2.x
1.2.x 1.2.x, 1.1.x 2.2.x, 2.1.x 0.10.1.x

Depending on the selected release-combination, the dependent projects will be referenced transitively when using maven or gradle for version management.

*The 2.0.x binder uses the pure java AdminClient to provision topics. When using the 0.11.x.x client, topics can be provisioned, but the number of partitions cannot be automatically adjusted up. To increase the number of topics, you must use the kafka tools instead. The property spring.cloud.stream.kafka.binder.auto-add-partitions must be false (default).
** To use the 0.11.x.x kafka-clients with 1.3.x, you must use the spring-cloud-stream-binder-kafka11 jar (instead of spring-cloud-stream-binder-kafka). You must also override certain other jar versions as follows:

spring-cloud-stream-binder-kafka11 1.3.0.RELEASE or higher
spring-kafka 1.3.2.RELEASE or higher
spring-integration-kafka 2.3.0.RELEASE or higher
spring-integration-core 4.3.13.RELEASE or higher
spring-integration-jmx 4.3.13.RELEASE or higher
kafka_2.11 (same version as kafka-clients)