Two Scoops of Scala

Transcript

1. Two scoops of Scala & Unfiltered April 2014 FullContact techTalk

   @skazhy

2. Scala? • object oriented and functional programming language • Type

   safe • Runs on JVM

3. Unfiltered? • A toolkit for HTTP in Scala • Really,

   really modular • Works with Netty and Jetty • Built for meetup.com realtime API • Makes good use of Scala's idioms

4. Toolchain • SBT - Scala Build Tool • Best conventions

   from Maven world • Iterative development in SBT shell

5. My setup • IntelliJ + SBT console(s) inside tmux •

   IntelliJ 13 has SBT support baked in

6. Deployment • Works great with Jenkins & Asgard • Minimal

   configuration tweaks needed (wait for the next slide)

7. • A tool for fetching templates for Scala projects •

   g8 skazhy/unfiltered-netty-rx • All SBT plugins for deployment and IntelliJ are included Bootstrapping with giter8

8. Using opinionated RESTful frameworks for microservices?

9. None

10. Example time!

11. object MyPlan extends cycle.Plan with cycle.ThreadPool with ServerErrorResponse { def

    intent = { case GET(Path("/")) => ResponseString("Hello!") case OPTIONS(_) => Created ~> Location("/foo") case _ => NotFound } } unfiltered.netty.Http(1337).handler(MyPlan).run()

12. An Intent is a partial function that pattern matches HTTP

    requests

13. A Plan is a binding between intent and the underlying

    interface

14. Pattern matching • Decomposing data structures to extract certain fields

    or validate them • Really powerful in Scala • “routing” mechanism in Unfiltered
15. None

16. Match on request methods • Use builtins: GET(_) POST(_) PATCH(_)

    • Or define your own: object SPACEJUMP extends Method("SPACEJUMP")

17. What happens under the hood? class Method(method: String) { def

    unapply[T](req: HttpRequest[T]) = if (req.method.equalsIgnoreCase(method)) Some(req) else None } object POST extends Method("POST")

18. Match on request headers BasicAuth(username, password) UserAgent("Cobook")

19. ...on URN Path("/foobar") Path(Seg("contactLists" :: "v2" :: listId :: Nil))

    // Will extract /contactLists/v2/1234

20. ...or query parameters object AccountIdParam extends Params.Extract("numericId", Params.first ~> Params.nonempty

    ~> Params.long) PATCH(Params(AccountIdParam(accountId))) // Will extract 1234 from PATCH /foo?numericId=1234
21. None

22. function composition!

23. Responses are composable case _ => Unauthorized ~> ResponseString("No pasaran")

    ~> ResponseHeader("WWW-Authenticate", "Basic realm=foo")

24. • HTTP requests are stateless • HTTP responses are side

    effects

25. Async made easy case req @ GET(Path("/async")) => val futureOp

    = asyncOperation futureOp.onSuccess { case result => req.respond(Ok ~> ResponseString(result)) } futureOp.onFailure { case _ => req.respond(InternalServerError) }

26. Unfiltered plays well with RxJava too

27. case req @ GET(Path("/reactive")) => observableOp.subscribe( result => req.respond(ResponseString(result)) _

    => req.respond(InternalServerError) )

28. What about testing?

29. • Separate library for testing with Specs2 • Mocking with

    Mockito • Comes bundled with the giter8 template unfiltered-specs2

30. object OperationPostSpec extends Specification { "PATCH /foo" should { lazy

    val r = Http(url((host \ "foo").PATCH)) lazy val response = r() "return HTTP 200" in { response.getResponseStatus mustEqual 200 } } }

31. Consider using Unfiltered when you... • need an async &

    lightweight HTTP service • Have separate business logic • Want to leverage the λ-force

32. Questions?