Akka with Spring

Akka with Spring

• Actor를 만들때 필요한 의존성을 대표적인 Dependency Injection 프레임워크인 Spring를 이용하여 사용하는 방법에 대해 알아보자
• Spring Bean Cycle과 다르게 Akka Actor의 Life Cycle을 가지고 있는다.

Gradle

compile "org.springframework:spring-context:${spring.version}"

compile "com.typesafe.akka:akka-actor_2.11:${akka.version}"

Define Actor

@Component

@Scope(ConfigurableBeanFactory.SCOPE_PROTOTYPE)

public class GreetingActor extends UntypedActor {

    @Autowired

    private GreetingService greetingService;

  

    @Override

    public void onReceive(Object message) throws Throwable {

        if (message instanceof Greet) {

            String name = ((Greet) message).getName();

            getSender().tell(greetingService.greet(name), getSelf());

        } else {

            unhandled(message);

        }

    }

 

    public static class Greet {

        private String name;

        // standard constructors/getters

    }

}

• Actor의 Life Cycle와 맞추기 위해 Bean의 SCOPE을 PROTOTYPE으로 설정을 한다.
• 다른 Scope으로 활용하는 경우에는 제대로 작동이 되지 않을수가 있다.

Actor Extension

public class SpringExtension 

  extends AbstractExtensionId<SpringExtension.SpringExt> {

 

    public static final SpringExtension SPRING_EXTENSION_PROVIDER 

      = new SpringExtension();

 

    @Override

    public SpringExt createExtension(ExtendedActorSystem system) {

        return new SpringExt();

    }

 

    public static class SpringExt implements Extension {

        private volatile ApplicationContext applicationContext;

 

        public void initialize(ApplicationContext applicationContext) {

            this.applicationContext = applicationContext;

        }

 

        public Props props(String actorBeanName) {

            return Props.create(

              SpringActorProducer.class, applicationContext, actorBeanName);

        }

    }

}

• extension을 반드시 Singleton을 구현이 되어야 한다.
• ActorSystem 하나당 ActorExtension이 하나가 나와야 된다.

 SpringActorProducer

public class SpringActorProducer implements IndirectActorProducer {

 

    private ApplicationContext applicationContext;

 

    private String beanActorName;

 

    public SpringActorProducer(ApplicationContext applicationContext, 

      String beanActorName) {

        this.applicationContext = applicationContext;

        this.beanActorName = beanActorName;

    }

 

    @Override

    public Actor produce() {

        return (Actor) applicationContext.getBean(beanActorName);

    }

 

    @Override

    public Class<? extends Actor> actorClass() {

        return (Class<? extends Actor>) applicationContext

          .getType(beanActorName);

    }

}

• DI를 위한 actor Producer를 정의를 한다.
• 직접 Actor를 생성하는 것이 간적접(indirect)를 생성을 란다. Actor 객체를 applicationContext를 통해 가지고 온다.

Confiugration

@Configuration

@ComponentScan

public class AppConfiguration {

 

    @Autowired

    private ApplicationContext applicationContext;

 

    @Bean

    public ActorSystem actorSystem() {

        ActorSystem system = ActorSystem.create("akka-spring-demo");

        SPRING_EXTENSION_PROVIDER.get(system)

          .initialize(applicationContext);

        return system;

    }

}

Use

ActorRef greeter = system.actorOf(SPRING_EXTENSION_PROVIDER.get(system)

  .props("greetingActor"), "greeter");

 

FiniteDuration duration = FiniteDuration.create(1, TimeUnit.SECONDS);

Timeout timeout = Timeout.durationToTimeout(duration);

 

Future<Object> result = ask(greeter, new Greet("John"), timeout);

 

Assert.assertEquals("Hello, John", Await.result(result, duration));

Reference

https://www.baeldung.com/akka-with-spring