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Fixed Queue Location Transparency

This is a more complex implementation of the Request Reply pattern, basically it uses a fixed queue for responses but with a continuous listening mechanism, which allows for more dynamic response handling and increases performance.

This scenario uses an external shared storage (like Redis, Memcached, or a database) to map correlation IDs to specific client instances. This way, when a response is received, any instance can look up the correct client instance to forward the response to the appropriate instance through a HTTP request.

For example, you define an interface like the next, so it could be auto implemented by the library: this MyRequestReplySingleInstance

To achieve the auto implementation, you should:

  1. Annotate the application or a configuration bean with @EnableMQGateway, optionally you can define the base package
   @SpringBootApplication(scanBasePackages = "co.com.bancolombia")
   @EnableMQGateway(scanBasePackages = "co.com.bancolombia")
   public class MainApplication {
      public static void main(String[] args) {
          SpringApplication.run(MainApplication.class);
      }
   }
  1. Annotate the interface with @ReqReply, for example
  @ReqReply(requestQueue = "DEV.QUEUE.1", replyQueue = "DEV.QUEUE.2", queueType = FIXED_LOCATION_TRANSPARENCY) // in queue names you can use ${some.property.name} spring placeholder notation
  public interface MyRequestReply extends MQRequestReply {
  }
  1. Now you can inject your interface in any spring component. MyRequestReplyAdapter
  @Component
  @AllArgsConstructor
  public class MyRequestReplyAdapter implements RequestGateway {
      private final MyRequestReply requestReply;
      ...
  }

And you can use the next methods to send and receive messages

  Mono<T> requestReply(String message);

  Mono<T> requestReply(String message, Duration timeout);

  Mono<T> requestReply(MQMessageCreator messageCreator);

  Mono<T> requestReply(MQMessageCreator messageCreator, Duration timeout);

Is possible that you require to add the line before the SpringApplication.run(MainApplication.class, args); like:

public static void main(String[] args) {
  System.setProperty("spring.devtools.restart.enabled", "false");
  SpringApplication.run(MainApplication.class, args);
}

Additional Configuration​

You should import the additional dependency:

implementation 'com.github.bancolombia:commons-jms-http-replier:<latest-version-here>'

Add annotation to one of your configuration beans or main application class

@EnableMQHttpReplies
@Configuration
public class SomeConfiguration {
    ...
}

Location Manager​

You should implement your own LocationManager instance:

public interface LocationManager {

    Mono<Void> set(String id, Duration timeout);

    Mono<String> get(String id);
}

For example RedisCache

HTTP Server​

You also need to import the default http server configuration, to achieve this you can define the next configuration properties:

commons.jms.reply.port: 8000 # Port should be different from the exposed by the application
commons.jms.reply.timeout: 5000 # milliseconds