How to retrieve List by a Consumer with Spring and rabbitmq - spring-mvc

Question

I have two projects
WebApp(SpringMVC)
Microservice
The idea is that I have a page in which I list all the users from DB, so basically I need a listener on WebApp side and a producer in the microservice side, typically the flow is as follow
Whitout rabbitmq(synchronous)
Click page "List Users"
UserController that redirect me to a specific service
public List<User>getUsers(){//no args!!
service.getUsers();//no args
}
UserService with logic to access DB and retrieve all users
public List<User>getUsers(){//no args!!
//connect to DB and retrieve all users
return users
}
Render users on jsp
With RabbitMQ and assuming users has already been produced the list of users on the microservice's side
My question is about if I introduce rabbitmq then I need a method in which I listen a message(List of products as a JSON) but now the flow change a little bit comparing with the first one because
Click button "List Users"
Controller need a method findAll(Message message), here I need pass a message because the service is expecting one as the service is Listener
public List<User>getUsers(Message message){
service.getAllUsers(**String message**);
}
The service as right now is listen a message, I need to pass a Message
arg in which I will be listen the queues
#RabbitListener(queues = "${queue}", containerFactory = "fac")
public List<User> getUsers(String message){
//Transform JSON to POJO
//some logic...
return users;
}
So basically my question is the second flow is correct?
If so how I have to pass the Message object from controller to service
because in controller I do not needed a Message, but in order to
listen I have, is this correct?
If so how pass the message arg
There is a better way to achieve this?
Regards

Answer 1

Use a Jackson2JsonMessageConverter and the framework will do all the conversion for you.
Controller:
List<User> users = template.convertSendAndReceiveAsType("someExchange", "someRoutingKey",
myRequestPojo, new ParameterizedTypeReference<List<User>>() {});
Server:
#RabbitListener(queues = "${queue}", containerFactory = "fac")
public List<User> getUsers(SomeRequestPojo request){
//some logic...
return users;
}
Wire the converter into both the listener container factory and the RabbitTemplate.
Request Pojo and Users have to be Jackson-friendly (no-arg constructor, setters).