CODEWITHSUNDEEP
springapache-kafkaspring-cloud-stream
eskimoquinn
eskimoquinn

Reputation: 1

Spring Cloud Stream Kafka: org.springframework.integration.MessageDispatchingException: Dispatcher has no subscribers

I am trying to use Spring Cloud Stream Kafka Binding to send and receive messages with a local zookeeper and kafka server. However, when starting up Spring MVC server, I am seeing the following exception: 

Caused by: org.springframework.integration.MessageDispatchingException: Dispatcher has no subscribers
at org.springframework.integration.dispatcher.UnicastingDispatcher.doDispatch(UnicastingDispatcher.java:154) ~[spring-integration-core-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at org.springframework.integration.dispatcher.UnicastingDispatcher.dispatch(UnicastingDispatcher.java:121) ~[spring-integration-core-4.3.5.RELEASE.jar:4.3.5.RELEASE]
at org.springframework.integration.channel.AbstractSubscribableChannel.doSend(AbstractSubscribableChannel.java:77) ~[spring-integration-core-4.3.5.RELEASE.jar:4.3.5.RELEASE]
... 28 common frames omitted

The server is very simple, one class and one spring application property file:

package com.example;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.stream.annotation.EnableBinding;
import org.springframework.cloud.stream.annotation.Output;
import org.springframework.messaging.Message;
import org.springframework.messaging.MessageChannel;
import org.springframework.messaging.support.MessageBuilder;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RestController;

import javax.annotation.PostConstruct;
import java.util.Map;

@RestController
@EnableBinding(ProducerChannels.class)
@SpringBootApplication
public class ProducerApplication {

  private final MessageChannel consumer;

  public ProducerApplication(ProducerChannels channels){
      this.consumer = channels.consumer();
  }

  @PostMapping("/greet/{name}")
  public void publish(@RequestBody Map<String, String> name){
      String greeting = "Hello, " + name + "!";

      Message<String> msg = MessageBuilder.withPayload(greeting).build();

      consumer.send(msg);
  }

  public static void main(String[] args) {
      SpringApplication.run(ProducerApplication.class, args);
  }
}

interface ProducerChannels {

  @Output
  MessageChannel consumer();
}

Blockquote spring.cloud.stream.kafka.bindings.consumer.destination = consumer server.port=8080

What else do I need to do to configure Spring Cloud Stream?

Upvotes: 0

Views: 939

Answers (2)

eomercelik
eomercelik

Reputation: 595

consumer is a special keyword. You shouldn't use it. I think it will happen if you fix it as below.

public interface ProducerChannels {
    
    String OUTPUT = "example-topic";

    @Output(OUTPUT)
    MessageChannel exampleTopic();
}

application.yml file

spring:
  cloud:
    stream:
      kafka:
        binder:
          brokers: localhost:9092
      bindings:
        example-topic:
          destination: example-topic
          contentType: application/json

Or

spring.cloud.stream.bindings.exampleTopic.destination= example-topic

Upvotes: 0

Gary Russell
Gary Russell

Reputation: 174504

What version(s) are you using? I just pasted your code into a boot 1.4.2 app (1.1.0.RELEASE for the stream starter) and it works fine for me.

Upvotes: 1

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