recipe-messaging-rabbitmq/src/docs/asciidoc/recipe-messaging-rabbitmq.adoc

:virgo-homepage: https://eclipse.org/virgo
:guide-short-name: messaging-rabbitmq
:recipe-name: Messaging with RabbitMQ
:recipe-short-name: recipe-{guide-short-name}
:experimental: true

include::../../../../recipe-template/src/docs/asciidoc/00_title.adoc[]
include::../../../../recipe-template/src/docs/asciidoc/01_acknowledgements.adoc[]

== {recipe-name}

The original guide uses https://projects.spring.io/spring-boot/[Spring Boot] to bootstrap the demo application. This guide shows what needs to be done to run {recipe-name} with Virgo.

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include::../../../../recipe-template/src/docs/asciidoc/04_ingredients.adoc[]
* OSGi Metadata
* Spring configuration

== Preparations

include::../../../../recipe-template/src/docs/asciidoc/051_get-the-code.adoc[]
include::../../../../recipe-template/src/docs/asciidoc/052_create-recipe-runtime.adoc[]
include::../../../../recipe-template/src/docs/asciidoc/053_create-eclipse-project-metadata.adoc[]
include::../../../../recipe-template/src/docs/asciidoc/054_prepare-virgo-tooling.adoc[]
include::../../../../recipe-template/src/docs/asciidoc/055_import-the-code.adoc[]
include::../../../../recipe-template/src/docs/asciidoc/056_create-new-virgo-server.adoc[]

== Directions

[NOTE]
--
In the original guide the music plays in the run method of the `CommandLineRunner` of the Spring Boot application.
--

`*@Configuration*` => `*<XML/>*`

////
The configuration hosted inside the `Application`, too has to be converted into `<XML/>`.
////

We are going to transform the `@SpringBootApplication` into a plain `@Component` with an `init`-method.


=== Spring Boot Application

[source,java]
----
@SpringBootApplication // <1>
public class Application implements CommandLineRunner { // <2>

  @Autowired private CustomerRepository repository; // <3>

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

  public void run(String... args) throws Exception { // <4>
    // messaging actions...
  }
}
----
<1> Will be replaced with a plain `@Component`.
<2> `CommandLineRunner` will be replaced, too.
<3> `@Autowired` is the common denominator.
<4> Will be replaced with a `@PostConstruct` method.

=== Virgoized Application

After the transformation the component looks something like:

[source,java]
----
@Component
public class Application {

  @Autowired private CustomerRepository repository;

  @PostConstruct
  public void init() throws Exception {
    // messaging actions...
  }
}
----

=== Message Receiver

The `Receiver` is unchanged:

[source,java]
----
include::../../../org.eclipse.virgo.samples.recipe.messaging.rabbitmq/src/main/java/org/eclipse/virgo/samples/recipe/messaging/rabbitmq/Receiver.java[tags=type]
----

=== RabbitMQ Queue

[source,java]
----
@Bean
Queue queue() {
  return new Queue("spring-boot", false);
}
----

vs.

[source,xml,ident=0]
----
include::../../../org.eclipse.virgo.samples.recipe.messaging.rabbitmq/src/main/resources/META-INF/spring/applicationContext.xml[tags=queue]
----

=== RabbitMQ Exchange

[source,java]
----
@Bean
TopicExchange exchange() {
  return new TopicExchange("spring-boot-exchange");
}
----

vs.

[source,xml,ident=0]
----
include::../../../org.eclipse.virgo.samples.recipe.messaging.rabbitmq/src/main/resources/META-INF/spring/applicationContext.xml[tags=exchange]
----

=== Binding

[source,java]
----
@Bean
Binding binding(Queue queue, TopicExchange exchange) {
  return BindingBuilder.bind(queue).to(exchange).with(queueName);
}
----

vs.

[source,xml,ident=0]
----
include::../../../org.eclipse.virgo.samples.recipe.messaging.rabbitmq/src/main/resources/META-INF/spring/applicationContext.xml[tags=binding]
----

=== Connection Factory and Rabbit Template

[TIP]
--
Spring Boot automatically creates a `*ConnectionFactory*` and `*RabbitTemplate*`.
--

[source,xml,ident=0]
----
include::../../../org.eclipse.virgo.samples.recipe.messaging.rabbitmq/src/main/resources/META-INF/spring/applicationContext.xml[tags=connection_factory]
----

[source,xml,ident=0]
----
include::../../../org.eclipse.virgo.samples.recipe.messaging.rabbitmq/src/main/resources/META-INF/spring/applicationContext.xml[tags=rabbit_template]
----

=== Message Listener

[source,java]
----
@Bean
SimpleMessageListenerContainer container(ConnectionFactory connectionFactory, MessageListenerAdapter listenerAdapter) {
  SimpleMessageListenerContainer container = new SimpleMessageListenerContainer();
  container.setConnectionFactory(connectionFactory);
  container.setQueueNames(queueName);
  container.setMessageListener(listenerAdapter);
  return container;
}
----

vs.

[source,xml,ident=0]
----
include::../../../org.eclipse.virgo.samples.recipe.messaging.rabbitmq/src/main/resources/META-INF/spring/applicationContext.xml[tags=message_listener_container]
----

=== OSGi Metadata

The OSGi metadata is generated from a template:

[source,java]
.template.mf
----
include::../../../org.eclipse.virgo.samples.recipe.messaging.rabbitmq/template.mf[]
----

== Let's taste

[source,txt]
.log.log
----
System.out                           Waiting five seconds...
System.out                           Sending message...
...
o.s.a.r.c.CachingConnectionFactory   Created new connection: SimpleConnection@63fa2ace [delegate=amqp://guest@192.168.64.3:5672/]
...
System.out                           Received <Hello from RabbitMQ!>
----

include::08_dockerize_recipe.adoc[]