In Spring Cloud Stream nomenclature, the interface that may be implemented to provide connection to physical destinations at the external middleware is called binder. Currently, there are two available built-in binder implementations—Kafka and RabbitMQ. In case you would like to provide a custom binder library, the key interface that is an abstraction for a strategy for connecting inputs and outputs to external middleware is Binder, having two methods—bindConsumer and bindProducer. For more details, you may refer to the Spring Cloud Stream specifications.
The important thing for us is an ability to use multiple binders in a single application. You can even mix different implementations, for example, RabbitMQ with Kafka. Spring Cloud Stream relies on Spring Boot's auto-configuration in the binding process. The implementation available on the classpath is used automatically. In case you would like to use both the default Binders, include the following dependencies to the project...