Getting some REST with Spray

Adding a RESTful API layer to your application can be easy, fast and reliable, using Spray

Transcript

1. Getting Some REST With Spray Nimrod Argov
2. –spray.io “Open source toolkit for building REST/HTTP-based integration layers on top of Scala and Akka”
3. Another HTTP Framework?
4. Netty Servlets Undertow Play! …
5. Sure we can.
6. Is it good enough?
7. Things We Don’t Want Containers XML Mutability Java under the surface <?xml version="1.0" encoding="ISO-8859-1"?> <!DOCTYPE web-app PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN" "http://java.sun.com/dtd/web-app_2_3.dtd"> <web-app> <servlet> <servlet-name>controlServlet</servlet-name> <servlet-class> com.jenkov.butterfly.ControlServlet </servlet-class> </servlet> <servlet-mapping> <servlet-name>controlServlet</servlet-name> <url-pattern>*.html</url-pattern> </servlet-mapping> </web-app>
8. Not a Framework A set of libraries for http integration
9. Testable and not just e2e
10. Scala Case Classes Functions as Values Collections Type Safety
11. Akka Concurrency Model Actors Unified Management
12. Spray Under the Hood Scala Akka Actors & Futures Akka I/O (used to be spray-io) Thread Pool / Config / Logging by Akka
13. Main Modules Server DSL (spray-routing) Client DSL (spray-client) Low-level HTTP Server/Client (spray-can) HTTP Data Model (spray-http) Test Kit (spray-testkit)
14. Spray Routing
15. Hello, World! val myRoute =
 path("hello"){
 complete {
 "world"
 }
 } object MyServiceActor extends App with SimpleRoutingApp with MyService {
 implicit val system = ActorSystem("MyService-System")
 
 startServer(interface = "localhost", port = 9090)(myRoute)
 }

16. Routes type Route = RequestContext => Unit ctx => ctx.complete(“response”) complete("response")
17. Route Composition Transform request / response for inner nested routes Filter requests for certain routes by Method Path Params … Route Chaining - Try a different route
18. Directives Context Transformations Filtering Value Extraction Request Completion
19. Directives - Chaining val route = a { b { c { ... // route 1 } ~ d { ... // route 2 } ~ ... // route 3 } ~ e { ... // route 4 } }
20. Directives - Filtering val myRoute =
 path("hello") {
 get {
 complete {
 "world"
 }
 }
 } ~
 path("hi") {
 post {
 complete("Hello World!")
 }
 }
21. Directives - Extraction val myRoute =
 path("student" / IntNumber){ id =>
 complete(s"student id received: $id")
 }
22. Directives - Composition val getOrPost = get | post val myRoute = (path("test") & getOrPost) {
 complete("This could have been a get or a post only")
 }
23. Directives - Composition val teacher = "teacher" / IntNumber
 
 val course = "course" / IntNumber
 
 val teacherCourse = path(teacher / course)
 val myRoute = teacherCourse { (teacherId, courseId) =>
 complete(s"Got teacher $teacherId and course $courseId")
 }
24. Directives - Composition val teacher = "teacher" / IntNumber
 
 val course = "course" / IntNumber
 
 val teacherCourse = path(teacher / course)
 val myRoute = (teacherCourse & getOrPost){ (teacherId, courseId) =>
 complete(s"Got teacher $teacherId and course $courseId")
 }
25. Directives - Composition val teacher = "teacher" / IntNumber
 
 val course = "course" / IntNumber
 
 val teacherCourse = path(teacher / course)
 val getOrPostTeacherCourse = teacherCourse & getOrPost val myRoute = getOrPostTeacherCourse { (teacherId, courseId) =>
 complete(s"Got teacher $teacherId and course $courseId")
 }
26. Directives - Type Safety val teacher = "teacher" / IntNumber (teacher | get){ teacherId =>
 complete(s"Got teacher $teacherId")
 }
 DOES NOT COMPILE!
27. Directives - Many Variations path("hi") {
 post {
 parameter("param".as[Int]) { param =>
 validate(param > 0, "Sorry, param has to be greater than zero"){
 complete("Hello World!" * param)
 }
 }
 }
 }
28. Rejections val noSuchPageHandler = RejectionHandler {
 case Nil => complete(NotFound, "Sorry, it's not here!")
 }
 val myRoute = getOrPostTeacherCourse { (teacherId, courseId) =>
 handleRejections(noSuchPageHandler) {
 complete(s"Got teacher $teacherId and course $courseId")
 }
 }
29. Rejections - Selective implicit val generalRejectionHandler = RejectionHandler {
 case MissingQueryParamRejection("id") :: _ => 
 complete(BadRequest, "Looks like a bug to me!")
 }
30. Asynchronous Processing class CalculatingActor extends Actor {
 override def receive = {
 case _ => sender ! 42
 }
 } val calculator: ActorRef = 
 actorRefFactory.actorOf(Props[CalculatingActor]) path("calc") {
 complete{
 (calculator ? "calc").
 mapTo[Int].
 map(result => s"calculation result is $result")
 }
 }
31. Testing
32. TestKit Support for specs2 and Scalatest No need for the actual server Does use an actor system
33. TestKit REQUEST ~> ROUTE ~> check {
 ASSERTIONS
 }

34. TestKit class RouteTest extends Specification with Specs2RouteTest with MyService{ 
 def actorRefFactory = system
 
 "My REST service" should {
 "Answer a hello message" in {
 Get("/hello") ~> myRoute ~> check {
 responseAs[String] === "world"
 }
 } } }
35. TestKit class RouteTest extends Specification with Specs2RouteTest with MyService{ 
 def actorRefFactory = system
 
 "My REST service" should {
 "Reject a POST request" in {
 Post("/hello") ~> myRoute ~> check {
 rejection === MethodRejection(HttpMethods.GET)
 }
 }
 }
 }

36. TestKit class RouteTest extends Specification with Specs2RouteTest with MyService{ 
 def actorRefFactory = system
 
 "My REST service" should {
 "Reject a POST request" in {
 Post("/hello") ~> sealRoute(myRoute) ~> check {
 status === MethodNotAllowed
 }
 }
 }
 }

37. Future[Spray]?
38. Akka-HTTP Spray 2.0 Polishing of APIs Java APIs Based on Reactive Streams
39. Akka-HTTP Better API for handling chunked messages Client Overhaul Websockets support (spray doesn’t support out of the box)
40. References http://spray.io/documentation/ https://github.com/spray/spray/tree/master/examples nimroda at wix dot com @nimrodargov