spring-amqp | Spring AMQP - support for Spring programming model | Pub Sub library

I’m using Spring AMQP and Spring Boot @Configuration and @Bean annotations in order to create all required queues, exchanges and bindings.

I have this gradle configuration with the following dependencies:

My application set up is mentioned as part of issue# Correct way of using spring webclient in spring amqp where I am trying to use Spring webclient to make API calls in Spring AMQP rabbit MQ consumer threads. Issue seems to be that parallel flux blocking call just stalls or takes a very long time after first few requests are fired.

To simulate this, I did below minimalistic set up -

Dependencies used

I used to have a @RabbitListener that works fine like this:

We want to write tests for a project that uses Spring Boot and Spring AMQP. As we code in Kotlin we would like to use MockK instead of Mockito as it better fits Kotlin code style and best practices.

The RabbitListenerTestHarness class provides some convienient feature for testing @RabbitListeners. However, it returns implementations of Mockito's Answer interface, which are incompatible with the Answer interface of MockK.

Is there a way to use the Mockito answers with MockK, e.g. some exisiting wrappers for interoperability?

Consider the following example listener:

I have 2 spring boot based microservices which interact through events. Producer microservice sends an event which is a POJO to RabbitMQ queue. Consumer microservice listens to the queue. The POJO has 2 java.time.Instant fields which spoils the serialization/de-serialization process. For now I have commented out these fields & it is working. I have tried by declaring a Jackson2JsonMessageConverter bean:

The doc explains why DMLC was introduced in version 2: https://docs.spring.io/spring-amqp/reference/html/#choose-container

This architecture was required because, in early versions of the RabbitMQ client, multiple concurrent deliveries were not possible. Newer versions of the client have a revised threading model and can now support concurrency. This has allowed the introduction of the DMLC where the listener is now invoked directly on the RabbitMQ Client thread. Its architecture is, therefore, actually “simpler” than the SMLC.

As mentioned in the doc: a revised threading model and can now support concurrency.

Can I simply understand it like this:

The previous version of the client will not make concurrent calls to the handleDelivery method, so we need to use a queue : just put the message in the queue and wait for other thread to consume, so handleDelivery method will return immediately to avoid blocking subsequent delivery, but the new version of the rabbit client will call the handleDelivery method concurrently, so there is no need to use an queue to support concurrency.

Can someone explain in more detail about what kind of threading model changes led to DMLC?

I'm creating application using Spring Boot with RabbitMQ. I've created configuration for Rabbit like this:

I have some Spring applications that communicate between them using RabbitMQ as broker. I can send and receive messages asynchronously between them. But now, I need one application to send a message to another one and wait for the response. So, for this I am trying to implement the RPC pattern. It is working, but the problem is that I could only do it using temporary queues generated by Spring.

https://www.rabbitmq.com/tutorials/tutorial-six-spring-amqp.html

This is the code that sends the message and wait for the response.