Spring Cloud Stream

External

• https://cloud.spring.io/spring-cloud-stream/
• https://cloud.spring.io/spring-cloud-stream-app-starters/
• Reference Spring Cloud Stream Core https://docs.spring.io/spring-cloud-stream/docs/Elmhurst.RELEASE/reference/htmlsingle/#_spring_cloud_stream_core

Internal

• Spring Cloud

Overview

Spring Cloud Stream is a framework for building highly scalable event-driven microservices connected with shared messaging systems. Spring applications use Spring Cloud Stream libraries to bind to a messaging middleware. Spring Cloud Stream builds upon Spring Boot to create standalone production-grade applications and uses Spring Integration to provide connectivity to message brokers.

Concepts

Destination Binder

The component responsible to provide integration with external messaging systems. Available binders:

• Rabbit Binder
• Kafka Binder
• AWS Kinesis Binder
• Google Cloud PubSub Binder

Destination Binding

Bridge between the external messaging system and application-provided Producers and Consumers of messages. The Producers and Consumers are created by the Destination Binders.

Interfaces

Sink

Input and no output.

public interface Sink {
  String INPUT = "input";

  @Input(Sink.INPUT)
  SubscribableChannel input();
}

Channel

Input Channel

An input channel funnels received messages into the application

Output Channel

Published messages leave the application via output channels.

Destination

The destination can be a queue, topic, or others.

Message

The canonical data structure used by Producers and Consumers to communicate with Destination Binders, and thus other applications via external messaging systems.

Message Handler

Is this the same thing as the handler method?

@StreamListener(Sink.INPUT)
public void handle(...) {
...
}

Also see @StreamListener.

Annotations

• @EnableBinding - provides immediate connectivity to a message broker.
• @StreamListener - annotates a handler method to receive events for stream processing.
• @Input
• @Output