java - spring boot rabbitmq MappingJackson2MessageConverter custom object conversion

Question

I'm trying to create a simple spring boot app with spring boot that "produce" messages to a rabbitmq exchange/queue and another sample spring boot app that "consume" these messages. So I have two apps (or microservices if you wish). 1) "producer" microservice 2) "consumer" microservice

The "producer" has 2 domain objects. Foo and Bar which should be converted to json and send to rabbitmq. The "consumer" should receive and convert the json message into a domain Foo and Bar respectively. For some reason I can not make this simple task. There are not much examples about this. For the message converter I want to use org.springframework.messaging.converter.MappingJackson2MessageConverter

Here is what I have so far:

PRODUCER MICROSERVICE

package demo.producer;

import org.springframework.amqp.core.Binding;
import org.springframework.amqp.core.BindingBuilder;
import org.springframework.amqp.core.Queue;
import org.springframework.amqp.core.TopicExchange;
import org.springframework.amqp.rabbit.core.RabbitMessagingTemplate;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.Bean;
import org.springframework.messaging.converter.MappingJackson2MessageConverter;
import org.springframework.stereotype.Service;

@SpringBootApplication
public class ProducerApplication implements CommandLineRunner {

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

    @Bean
    Queue queue() {
        return new Queue("queue", false);
    }

    @Bean
    TopicExchange exchange() {
        return new TopicExchange("exchange");
    }

    @Bean
    Binding binding(Queue queue, TopicExchange exchange) {
        return BindingBuilder.bind(queue).to(exchange).with("queue");
    }

    @Bean
    public MappingJackson2MessageConverter jackson2Converter() {
        MappingJackson2MessageConverter converter = new MappingJackson2MessageConverter();
        return converter;
    }

    @Autowired
    private Sender sender;

    @Override
    public void run(String... args) throws Exception {
        sender.sendToRabbitmq(new Foo(), new Bar());
    }
}

@Service
class Sender {

    @Autowired
    private RabbitMessagingTemplate rabbitMessagingTemplate;
    @Autowired
    private MappingJackson2MessageConverter mappingJackson2MessageConverter;

    public void sendToRabbitmq(final Foo foo, final Bar bar) {

        this.rabbitMessagingTemplate.setMessageConverter(this.mappingJackson2MessageConverter);

        this.rabbitMessagingTemplate.convertAndSend("exchange", "queue", foo);
        this.rabbitMessagingTemplate.convertAndSend("exchange", "queue", bar);

    }
}

class Bar {
    public int age = 33;
}

class Foo {
    public String name = "gustavo";
}

CONSUMER MICROSERVICE

package demo.consumer;

import org.springframework.amqp.rabbit.annotation.EnableRabbit;
import org.springframework.amqp.rabbit.annotation.RabbitListener;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.stereotype.Service;

@SpringBootApplication
@EnableRabbit
public class ConsumerApplication implements CommandLineRunner {

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

    @Autowired
    private Receiver receiver;

    @Override
    public void run(String... args) throws Exception {

    }

}

@Service
class Receiver {
    @RabbitListener(queues = "queue")
    public void receiveMessage(Foo foo) {
        System.out.println("Received <" + foo.name + ">");
    }

    @RabbitListener(queues = "queue")
    public void receiveMessage(Bar bar) {
        System.out.println("Received <" + bar.age + ">");
    }
}

class Foo {
    public String name;
}

class Bar {
    public int age;
}

And here is the exception I'm getting:

    org.springframework.amqp.rabbit.listener.exception.ListenerExecutionFailedException: Listener method could not be invoked with the incoming message
Endpoint handler details:
Method [public void demo.consumer.Receiver.receiveMessage(demo.consumer.Bar)]
Bean [demo.consumer.Receiver@1672fe87]
    at org.springframework.amqp.rabbit.listener.adapter.MessagingMessageListenerAdapter.invokeHandler(MessagingMessageListenerAdapter.java:116)
    at org.springframework.amqp.rabbit.listener.adapter.MessagingMessageListenerAdapter.onMessage(MessagingMessageListenerAdapter.java:93)
    at org.springframework.amqp.rabbit.listener.AbstractMessageListenerContainer.doInvokeListener(AbstractMessageListenerContainer.java:756)
    at org.springframework.amqp.rabbit.listener.AbstractMessageListenerContainer.invokeListener(AbstractMessageListenerContainer.java:679)
    at org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer.access$001(SimpleMessageListenerContainer.java:83)
    at org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer$1.invokeListener(SimpleMessageListenerContainer.java:170)
    at org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer.invokeListener(SimpleMessageListenerContainer.java:1257)
    at org.springframework.amqp.rabbit.listener.AbstractMessageListenerContainer.executeListener(AbstractMessageListenerContainer.java:660)
    at org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer.doReceiveAndExecute(SimpleMessageListenerContainer.java:1021)
    at org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer.receiveAndExecute(SimpleMessageListenerContainer.java:1005)
    at org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer.access$700(SimpleMessageListenerContainer.java:83)
    at org.springframework.amqp.rabbit.listener.SimpleMessageListenerContainer$AsyncMessageProcessingConsumer.run(SimpleMessageListenerContainer.java:1119)
    at java.lang.Thread.run(Thread.java:745)
Caused by: org.springframework.amqp.support.converter.MessageConversionException: Cannot handle message
    ... 13 common frames omitted
Caused by: org.springframework.messaging.converter.MessageConversionException: No converter found to convert to class demo.consumer.Bar, message=GenericMessage [payload=byte[10], headers={amqp_receivedRoutingKey=queue, amqp_receivedExchange=exchange, amqp_deliveryTag=1, amqp_deliveryMode=PERSISTENT, amqp_consumerQueue=queue, amqp_redelivered=false, id=87cf7e06-a78a-ddc1-71f5-c55066b46b11, amqp_consumerTag=amq.ctag-msWSwB4bYGWVO2diWSAHlw, contentType=application/json;charset=UTF-8, timestamp=1433989934574}]
    at org.springframework.messaging.handler.annotation.support.PayloadArgumentResolver.resolveArgument(PayloadArgumentResolver.java:115)
    at org.springframework.messaging.handler.invocation.HandlerMethodArgumentResolverComposite.resolveArgument(HandlerMethodArgumentResolverComposite.java:77)
    at org.springframework.messaging.handler.invocation.InvocableHandlerMethod.getMethodArgumentValues(InvocableHandlerMethod.java:127)
    at org.springframework.messaging.handler.invocation.InvocableHandlerMethod.invoke(InvocableHandlerMethod.java:100)
    at org.springframework.amqp.rabbit.listener.adapter.MessagingMessageListenerAdapter.invokeHandler(MessagingMessageListenerAdapter.java:113)
    ... 12 common frames omitted

The exception says there is no converter, and that is true, my problem is that I have no idea how to set the MappingJackson2MessageConverter converter in the consumer side (please note that I want to use org.springframework.messaging.converter.MappingJackson2MessageConverter and not org.springframework.amqp.support.converter.JsonMessageConverter)

Any thoughts ?

Just in case, you can fork this sample project at: https://github.com/gustavoorsi/rabbitmq-consumer-receiver

Answer 1

Ok, I finally got this working.

Spring uses a PayloadArgumentResolver to extract, convert and set the converted message to the method parameter annotated with @RabbitListener. Somehow we need to set the mappingJackson2MessageConverter into this object.

So, in the CONSUMER app, we need to implement RabbitListenerConfigurer. By overriding configureRabbitListeners(RabbitListenerEndpointRegistrar registrar) we can set a custom DefaultMessageHandlerMethodFactory, to this factory we set the message converter, and the factory will create our PayloadArgumentResolver with the the correct convert.

Here is a snippet of the code, I've also updated the git project.

ConsumerApplication.java

package demo.consumer;

import org.springframework.amqp.rabbit.annotation.EnableRabbit;
import org.springframework.amqp.rabbit.annotation.RabbitListener;
import org.springframework.amqp.rabbit.annotation.RabbitListenerConfigurer;
import org.springframework.amqp.rabbit.listener.RabbitListenerEndpointRegistrar;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.Bean;
import org.springframework.messaging.converter.MappingJackson2MessageConverter;
import org.springframework.messaging.handler.annotation.support.DefaultMessageHandlerMethodFactory;
import org.springframework.stereotype.Service;

@SpringBootApplication
@EnableRabbit
public class ConsumerApplication implements RabbitListenerConfigurer {

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

    @Bean
    public MappingJackson2MessageConverter jackson2Converter() {
        MappingJackson2MessageConverter converter = new MappingJackson2MessageConverter();
        return converter;
    }

    @Bean
    public DefaultMessageHandlerMethodFactory myHandlerMethodFactory() {
        DefaultMessageHandlerMethodFactory factory = new DefaultMessageHandlerMethodFactory();
        factory.setMessageConverter(jackson2Converter());
        return factory;
    }

    @Override
    public void configureRabbitListeners(RabbitListenerEndpointRegistrar registrar) {
        registrar.setMessageHandlerMethodFactory(myHandlerMethodFactory());
    }

    @Autowired
    private Receiver receiver;

}

@Service
class Receiver {
    @RabbitListener(queues = "queue")
    public void receiveMessage(Foo foo) {
        System.out.println("Received <" + foo.name + ">");
    }

    @RabbitListener(queues = "queue")
    public void receiveMessage(Bar bar) {
        System.out.println("Received <" + bar.age + ">");
    }
}

class Foo {
    public String name;
}

class Bar {
    public int age;
}

So, if you run the Producer microservice it will add 2 messages in the queue. One that represent a Foo object and another that represent a Bar object. By running the consumer microservice you will see that both are consumed by the respective method in the Receiver class.

---

Updated issue:

There is a conceptual problem about queuing from my side I think. What I wanted to achieved can not be possible by declaring 2 methods annotated with @RabbitListener that points to the same queue. The solution above was not working properly. If you send to rabbitmq, let say, 6 Foo messages and 3 Bar messages, they wont be received 6 times by the listener with Foo parameter. It seems that the listener are invoked in parallel so there is no way to discriminate which listener to invoke based on the method argument type. My solution (and I'm not sure if this is the best way, I'm open to suggestions here) is to create a queue for each entity. So now, I have queue.bar and queue.foo, and update @RabbitListener(queues = "queue.foo") Once again, I've updated the code and you can check it out in my git repository.