1 output bindings in Spring Cloud Stream Kafka Binder - spring

Question

in this page tells that you can't make just one Outputs
but I need to make just one Outputs by using Spring Cloud Stream Kafka Binder
what should I do?
some articles says that using org.springframework.cloud.stream.function.StreamBridge but it's not works for me
I made StreamBridge to send topics to Kafka but Kafka doesn't produce topics to my Spring boot application
and this is my application.yml and produce topic code
// producer Springboot application
spring.cloud.stream:
kafka:
binder:
brokers: {AWS.IP}:9092
zkNodes: {AWS.IP}:2181
bindings:
deliveryIncoming:
destination : deliveryIncomingtopic
#Bean
public CommandLineRunner commandLineRunner(ApplicationContext ctx) {
// wanna produce deliveryIncomingtopic and send to Spring's Consumer
}
// Consumer Springboot application
spring :
cloud:
stream:
kafka:
binder:
brokers: {AWS.IP}:9092
zkNodes: {AWS.IP}:2181
function:
definition : deliveryIncoming;
bindings:
deliveryIncoming-in-0:
destination : deliveryIncomingtopic
#Bean
public Consumer<KStream<String, String>> deliveryIncoming() {
return input ->
input.foreach((key, value) -> {
System.out.println("deliveryIncoming is playing");
System.out.println("Key: " + key + " Value: " + value);
});
}
EDIT
sorry I think I made kind of unclear
I just want to do like below
produce(deliveryIncomingtopic) -> Kafka -> consumer(deliveryIncomingtopic)

Answer 1

If that's the case, then you need to change your bean function definition to return java.util.Function instead of java.util.Consumer.
#Bean
public Function<KStream<String, String>, KStream<String, String>> deliveryIncoming() {
return input ->
input.foreach((key, value) -> {
System.out.println("deliveryIncoming is playing");
System.out.println("Key: " + key + " Value: " + value);
});
}
However, AFAIK.. you still need to define the output channel in your application.yml. You can use the same name with different suffix. Something like below :
deliveryIncoming-in-0:
destination: <your_topic_name>
deliveryIncoming-out-0:
destination: <your_topic_name>

Answer 2

Just want to make things clear here. Are you looking to consume a message from your inbound topic deliveryIncomingtopic and then generate/produce another message to another output topic ?
If that's your question about, then I believe you were missing something there within your application.yml.
You need to have another configuration for your output topic. e.g. :
Since you're using Spring Cloud Function (based on what i see in your application.yml), then you should add more configuration for your output topic as follow:
spring :
cloud:
stream:
kafka:
binder:
brokers: {AWS.IP}:9092
zkNodes: {AWS.IP}:2181
function:
definition: deliveryIncoming;deliveryOutput
bindings:
deliveryIncoming-in-0:
destination: deliveryIncomingtopic
deliveryOutput-out-0:
destination: deliveryOutput
And also define another bean for your producer function :
#Bean
public Producer<KStream<String, String>> deliveryOutput() {
// do your necessary logic here to outbound your message
}
Hope this will match your expectation.