This document discusses transitioning a team from Java to Scala. It covers reasons for choosing Scala like its syntax and libraries. It also discusses challenges like testing and shared state in Scala. It provides recommendations to incrementally introduce Scala to avoid issues and constantly learn the new language through projects.

1. Переход на Scala:
босиком по граблям

2. Data Processing Team

3. Java / Scala / Clojure / Groovy / ?
JVM

4. “Во-первых, это красиво…” *
Почему Scala?

5. akka-http / spray / finagle / play
REST & HTTP

6. Spray

7. Implicits

8. def strangeIdea(n: Int)(implicit s: String) = s * n

9. package spray.routing
...
trait HttpServiceBase extends Directives {
/**
* Supplies the actor behavior for executing the given route.
*/
def runRoute(route: Route)(implicit eh: ExceptionHandler, rh:
RejectionHandler, ac: ActorContext, rs: RoutingSettings, log:
LoggingContext): Actor.Receive = {...}

10. def createOrUpdateCookieProfileRoute(): Route = post {
pathPrefix(ApiVersion) {
pathPrefix("cookies" / Segment) { cookieId =>
path("cookieProfiles" / IntNumber) { trackingSetupId =>
parameters('cookieSetTime.as[DateTime].?, 'cookieLastSeenTime.as[DateTime].?) {
(cookieSetTime, cookieLastSeenTime) =>
entity(as[CookieProfile]) { cookieProfile =>
traceName("POST COOKIE PROFILE") { ctx =>
val serviceActor: ActorRef = newStorageServiceActor()
val message = MergeCookieProfile(ctx, cookieProfile, cookieSetTime, cookieLastSeenTime)
serviceActor.tell(message, ActorRef.noSender)
}
}
}
}
}
}
}

11. trait JsonSerializerSupport {
implicit val formats =
DefaultFormats ++
BinaryTypeSerializers.all ++
JodaTimeSerializers.all
}

12. https://github.com/gettyimages/spray-swagger
Swagger

13. @ApiOperation(
httpMethod = "POST", value = "Create/Update CookieProfile by cookieId and trackingSetupId",
notes = "Creates new CookieProfile if it doesn't exists or updates old one if it exists in storage.”)
@ApiImplicitParams(Array(
new ApiImplicitParam(
name = Fields.CookieId,
value = Description.CookieId,
required = true,
dataType = DataTypes.String,
paramType = ParamType.Path),
new ApiImplicitParam(
name = Fields.TrackingSetupId,
value = Description.TrackingSetupId,
required = true,
dataType = DataTypes.Integer,
paramType = ParamType.Path),
new ApiImplicitParam(
name = Fields.CookieSetTime,
value = Description.CookieSetTime,
dataType = DataTypes.String,
paramType = ParamType.Query),
new ApiImplicitParam(
name = Fields.CookieLastSeenTime,
value = Description.CookieLastSeenTime,
dataType = DataTypes.String,
paramType = ParamType.Query),
new ApiImplicitParam(
name = Fields.Body,
value = Description.Body,
required = true,
dataType = DataTypes.CookieProfile,
paramType = ParamType.Body)))
@ApiResponses(Array(
new ApiResponse(code = 200, message = Responses.Ok, response = classOf[SuccessResponse]),
new ApiResponse(code = 400, message = Responses.BadRequest, response = classOf[ErrorResponse]),
new ApiResponse(code = 500, message = Responses.InternalError, response = classOf[ErrorResponse]),
new ApiResponse(code = 503, message = Responses.ServiceUnavailable)))
@Path("/{cookieId}/cookieProfiles/{trackingSetupId}")

14. Akka

15. “blocking problem”

16. Shared state

17. Как это тестировать?

18. test("return 404 code for not existing cookie with cookieProfiles") {
Get("/v1/cookies/777/cookieProfiles") ~> route ~> check {
handled should be(right = true)
response.status should be(StatusCodes.NotFound)
}
}

19. http://gatling.io/
Нагрузочные тесты

20. DevOps

21. Отличное решение
Kamon
http://kamon.io/

22. Если вы сами готовы
его допиливать

23. ELK & Grafana

24. Maven & sbt

25. Что бы могло пойти не так?
Итак, вы решили
перейти на Scala

26. Сложность и
академичность

27. IDE

28. OOP & FP

29. Explicit is better than implicit
Много споров о стиле

31. Take it easy

32. Плавный переход к
Scala

33. Инкрементальное
внедрение языка

34. Постоянное изучение

35. “Технологии идеальны,
а люди – *удаки” **

36. Svetlana Bozhko aka @SBozhko
s.bozhko@adform.com
svt.bozhko@gmail.com
http://devzen.ru
Спасибо!

37. * — Старый анекдот
** — Baruch Sadogursky aka @jbaruch
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