Attention.md

Geographic Services (Scala)

Refer to GeographicService.scala. The code fetches Weather and nearby places information (both http calls to an end-point) and merges the 2 end-points responses to produce meaningful information as JSON string.

• Part 1
  • Use Future’s flatMap to get the aggregate result.
  • Re-write the same using for-comprehension.
  • In each case strive to use minimal variables.
  • Measure time taken in each case and compare the results. You may use the time function provided therein.
• Part 2
  • Running futures one after another turned out to be the same which the earlier sequential code was doing. By using Futures, we simply converted synchronous calls to asynchronous ones, devoid of any speed benefit.
  • Your task is to make this as fast as possible by running the futures in parallel. Make necessary modifications to both the versions of your earlier code.
  • Measure time taken in each case and compare the results and also with Part 1 cases.

GeographicService.scala

import scala.concurrent.{Future, Await}
import scala.concurrent.duration._
import scala.language.postfixOps

def time[T](f: Future[T], timeout: Duration = 5 seconds) = {
  val startTime = System.currentTimeMillis  
  val result = Await.result(f, timeout)
  val diff = System.currentTimeMillis - startTime
  println(s"Time Taken = $diff(ms).")
  result
} 

def getRequestData(url: String): String = io.Source.fromURL(url).mkString.trim

val host = "https://geographic-services.herokuapp.com"
val nearbyPath = "/places/nearby"
val weatherPath = "/weather"

// Mumbai Geo-loc
val lat = "lat=19.01"
val lon = "lon=72.8"

// Lord's Cricket Ground, London
// val lat = "lat=51.53"
// val lon =  "lon=-0.17"

val radius = "radius=25"
val units = "unit=km"

val placesNearbyUrl = s"$host$nearbyPath?$lat&$lon&$radius&$units"
val placesNearbyData = getRequestData(placesNearbyUrl)

val weatherUrl = s"$host$weatherPath?$lat&$lon"
val weatherData = getRequestData(weatherUrl)

val weatherAndPlacesNearby = s"""{ "weather" : $weatherData, "placesNearby": $placesNearbyData }"""

println(weatherAndPlacesNearby)