This version is still in development and is not considered stable yet. For the latest stable version, please use spring-cloud-stream 4.1.4!

Explicit binding creation

In the previous section we explained how bindings are created implicitly driven by the names of Function, Supplier or Consumer beans provided by your application. However, there are times when you may need to create binding explicitly where bindings are not tied to any function. This is typically done to support integrations with other frameworks via StreamBridge.

Spring Cloud Stream allows you to define input and output bindings explicitly via spring.cloud.stream.input-bindings and spring.cloud.stream.output-bindings properties. Noticed the plural in the property names allowing you to define multiple bindings by simply using ; as a delimiter. Just look at the following test case as an example:

@Test
public void testExplicitBindings() {
	try (ConfigurableApplicationContext context = new SpringApplicationBuilder(
		TestChannelBinderConfiguration.getCompleteConfiguration(EmptyConfiguration.class))
				.web(WebApplicationType.NONE)
				.run("--spring.jmx.enabled=false",
					"--spring.cloud.stream.input-bindings=fooin;barin",
					"--spring.cloud.stream.output-bindings=fooout;barout")) {


	. . .
	}
}

@EnableAutoConfiguration
@Configuration
public static class EmptyConfiguration {
}

As you can see we have declared two input bindings and two output bindings while our configuration had no functions defined, yet we were able to successfully create these bindings and access their corresponding channels.