<dependencies>
 <dependency>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-web</artifactId>
 </dependency>
 <dependency>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-amqp</artifactId>
 </dependency>
 <dependency>
  <groupId>com.thedeanda</groupId>
  <artifactId>lorem</artifactId>
 </dependency>
</dependencies>
@SpringBootApplication
public class BlockingApplication {
 public static void main(String[] args) {
  SpringApplication.run(BlockingApplication.class, args);
 }
 @RestController
 public static class MessageController {
  private final RabbitTemplate rabbitTemplate;
  public MessageController(CachingConnectionFactory connectionFactory) {
   this.rabbitTemplate = new RabbitTemplate(connectionFactory);
  }
  @GetMapping("invoke")
  public String sendMessage() {
   Message response = rabbitTemplate.sendAndReceive("uppercase", null, request());
   return new String(response.getBody());
  }
  private static Message request() {
   Lorem LOREM = LoremIpsum.getInstance();
   String name = LOREM.getFirstName() + " " + LOREM.getLastName();
   return new Message(name.getBytes(), new MessageProperties());
  }
 }
 @Bean
 public CachingConnectionFactory connectionFactory() {
  CachingConnectionFactory factory = new CachingConnectionFactory();
  factory.setAddresses("localhost:5672");
  factory.setUsername("admin");
  factory.setPassword("admin");
  return factory;
 }
}

<dependencies>
 <dependency>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-amqp</artifactId>
 </dependency>
</dependencies>
@SpringBootApplication
public class ServiceApplication {
 public static void main(String[] args) {
  SpringApplication.run(ServiceApplication.class, args);
 }
 public static class MessageListener {
  public String handleMessage(byte[] message) {
   Random rand = new Random();
   // Obtain a number between [0 - 49] + 50 = [50 - 99]
   int n = rand.nextInt(50) + 50;
   String content = new String(message);
   try {
    Thread.sleep(n);
   } catch (InterruptedException e) {
    e.printStackTrace();
   }
   return content.toUpperCase();
  }
 }
 @Bean
 public CachingConnectionFactory connectionFactory() {
  CachingConnectionFactory factory = new CachingConnectionFactory();
  factory.setAddresses("localhost:5672");
  factory.setUsername("admin");
  factory.setPassword("admin");
  return factory;
 }
 @Bean
 public SimpleMessageListenerContainer serviceListenerContainer() {
  SimpleMessageListenerContainer container = new SimpleMessageListenerContainer();
  container.setConnectionFactory(connectionFactory());
  container.setConcurrentConsumers(20);
  container.setMaxConcurrentConsumers(40);
  container.setQueueNames("uppercase_messages");
  container.setMessageListener(new MessageListenerAdapter(new MessageListener()));
  return container;
 }
}