如何将Akka流式溪流Kafka(反应性-Kafka)集成到Akka HTTP应用程序中

Question

我有一个基本的scala akka http crud应用程序。有关类的相关类，请参见下文。

我只是想在创建/更新实体时将一个实体ID和一些数据（作为JSON）编写给Kafka主题。

我正在寻找http://doc.akka.io/docs/akka-stream-kafka/current/producer.html，但是对Scala和Akka来说是新手，不确定如何将其集成到我的应用程序中？

例如，从上面的文档中，这是生产者写给卡夫卡的示例，所以我认为我需要类似的东西，但是在我的应用程序中，这是否应该去？在创建用户后，我可以在服务中的创建方法中添加另一个地图调用？

非常感谢！

val done = Source(1 to 100)
  .map(_.toString)
  .map { elem =>
    new ProducerRecord[Array[Byte], String]("topic1", elem)
  }
  .runWith(Producer.plainSink(producerSettings))

或我需要在我的server.scala？

中https://github.com/hseeberger/accessus做类似示例的事情。

weberver.scala

object System {
  implicit val system = ActorSystem()
  implicit val dispatcher = system.dispatcher
  implicit val actorMaterializer = ActorMaterializer()
}
object WebServer extends App {
  import System._
  val config = new ApplicationConfig() with ConfigLoader
  ConfigurationFactory.setConfigurationFactory(new LoggingConfFileConfigurationFactory(config.loggingConfig))
  val injector = Guice.createInjector(new MyAppModule(config))
  val routes = injector.getInstance(classOf[Router]).routes
  Http().bindAndHandle(routes, config.httpConfig.interface, config.httpConfig.port)
}

router.scala

def routes(): Route = {
    post {
      entity(as[User]) { user =>
        val createUser = userService.create(user)
        onSuccess(createUser) {
          case Invalid(y: NonEmptyList[Err]) =>  {
            throw new ValidationException(y)
          }
          case Valid(u: User) => {
              complete(ToResponseMarshallable((StatusCodes.Created, u)))
          }
        }
      }
    } ~
    // More routes here, left out for example  
}

service.scala

def create(user: User): Future[MaybeValid[User]] = {
    for {
      validating <- userValidation.validateCreate(user)
      result <- validating match {
        case Valid(x: User) =>
          userRepo.create(x)
            .map(dbUser => Valid(UserConverters.fromUserRow(x)))
        case y: DefInvalid =>
          Future{y}
      }
    } yield result
  }

repo.scala

def create(user: User): Future[User] = {
    mutateDbProvider.db.run(
      userTable returning userTable.map(_.userId)
        into ((user, id) => user.copy(userId = id)) +=
        user.copy(createdDate = Some(Timestamp.valueOf(LocalDateTime.now())))
    )
  }

Answer 1

由于您已经将Route写给了Entity的1 User，所以我认为您不需要Producer.plainSink。相反，我认为Producer.send也会工作。另外，作为旁注，抛出异常不是"惯用性" scala。因此，我更改了无效用户的逻辑：

val producer : KafkaProducer = new KafkaProducer(producerSettings)
val routes : Route = 
  post {
    entity(as[User]) { user =>
      val createUser = userService.create(user)
      onSuccess(createUser) {
        case Invalid(y: NonEmptyList[Err]) =>  
          complete(BadRequest -> "invalid user")
        case Valid(u: User) => { 
          val producerRecord = 
            new ProducerRecord[Array[Byte], String]("topic1",s"""{"userId" : ${u.userId}, "entity" : "User"}""")
          onComplete(producer send producerRecord) { _ =>
            complete(ToResponseMarshallable((StatusCodes.Created, u)))
          }
        }
      }
    }
  }