Spring Integration Channeling With Bean Name vs Method Name - spring

Question

I have PublishSubscribeChannel like this:
#Bean(name = {"publishCha.input", "publishCha2.input"}) //2 subscribers
public MessageChannel publishAction() {
PublishSubscribeChannel ps = MessageChannels.publishSubscribe().get();
ps.setMaxSubscribers(8);
return ps;
}
I have also subscriber channels:
#Bean
public IntegrationFlow publishCha() {
return f -> f
.handle(m -> System.out.println("In publishCha channel..."));
}
#Bean
public IntegrationFlow publishCha2() {
return f -> f
.handle(m -> System.out.println("In publishCha2 channel..."));
}
And finally another subscriber:
#Bean
public IntegrationFlow anotherChannel() {
return IntegrationFlows.from("publishAction")
.handle(m -> System.out.println("ANOTHER CHANNEL IS HERE!"))
.get();
}
The problem is, when I call channel with method name "publishAction" like below from another flow, it only prints "ANOTHER CHANNEL HERE" and ignores other subscribers. However, if I call with
.channel("publishCha.input"), this time it enters publishCha and publishCha2 subscribers but ignoring the third subscriber.
#Bean
public IntegrationFlow flow() {
return f -> f
.channel("publishAction");
}
My question is, why those two different channeling methods yields different results?
.channel("publishAction") // channeling with method name executes third subscriber
.channel("publishCha.input") // channelling with bean name, executes first and second subscribers
Edit: narayan-sambireddy requested how I send messages to channel. I send it via Gateway:
#MessagingGateway
public interface ExampleGateway {
#Gateway(requestChannel = "flow.input")
void flow(Order orders);
}
In Main:
Order order = new Order();
order.addItem("PC", "TTEL", 2000, 1)
ConfigurableApplicationContext ctx = SpringApplication.run(Start.class, args);
ctx.getBean(ExampleGateway.class).flow(order);

Answer 1

Your problem with the third subscriber that you miss the purpose of the name in the #Bean:
/**
* The name of this bean, or if several names, a primary bean name plus aliases.
* <p>If left unspecified, the name of the bean is the name of the annotated method.
* If specified, the method name is ignored.
* <p>The bean name and aliases may also be configured via the {#link #value}
* attribute if no other attributes are declared.
* #see #value
*/
#AliasFor("value")
String[] name() default {};
So, method name as a bean name is ignored in this case, therefore Spring Integration Java DSL doesn't find a bean with the publishAction and creates one - DirectChannel.
You can use method reference though:
IntegrationFlows.from(publishAction())
Or, if that is in a different configuration class, you can re-use one of the predefined name"
IntegrationFlows.from(publishCha.input)
This way DSL will re-use existing bean and will just add one more subscriber to that pub-sub channel.