spray-simple-client.scala

package spray.examples

import scala.util.{Success, Failure}
import scala.concurrent.duration._
import akka.actor.ActorSystem
import akka.pattern.ask
import akka.event.Logging
import akka.io.IO
import spray.json.{JsonFormat, DefaultJsonProtocol}
import spray.can.Http
import spray.httpx.SprayJsonSupport
import spray.client.pipelining._
import spray.util._

case class Elevation(location: Location, elevation: Double)
case class Location(lat: Double, lng: Double)
case class GoogleApiResult[T](status: String, results: List[T])

object ElevationJsonProtocol extends DefaultJsonProtocol {
  implicit val locationFormat = jsonFormat2(Location)
  implicit val elevationFormat = jsonFormat2(Elevation)
  implicit def googleApiResultFormat[T :JsonFormat] = jsonFormat2(GoogleApiResult.apply[T])
}

object Main extends App {
  // we need an ActorSystem to host our application in
  implicit val system = ActorSystem("simple-spray-client")
  import system.dispatcher // execution context for futures below
  val log = Logging(system, getClass)

  log.info("Requesting the elevation of Mt. Everest from Googles Elevation API...")

  import ElevationJsonProtocol._
  import SprayJsonSupport._
  val pipeline = sendReceive ~> unmarshal[GoogleApiResult[Elevation]]

  val responseFuture = pipeline {
    Get("http://maps.googleapis.com/maps/api/elevation/json?locations=27.988056,86.925278&sensor=false")
  }
  responseFuture onComplete {
    case Success(GoogleApiResult(_, Elevation(_, elevation) :: _)) =>
      log.info("The elevation of Mt. Everest is: {} m", elevation)
      shutdown()

    case Success(somethingUnexpected) =>
      log.warning("The Google API call was successful but returned something unexpected: '{}'.", somethingUnexpected)
      shutdown()

    case Failure(error) =>
      log.error(error, "Couldn't get elevation")
      shutdown()
  }

  def shutdown(): Unit = {
    IO(Http).ask(Http.CloseAll)(1.second).await
    system.shutdown()
  }
}