Send request at regular interval - scala

Question

Hello I am trying to learn akka-http and make a simple client for a rest api. I would like to know how to send a request to a rest server at regular interval.
I have my simple client:
object RestClientApp extends App {
// set up ActorSystem and other dependencies here
//#main-class
//#server-bootstrapping
implicit val system: ActorSystem = ActorSystem()
implicit val materializer: ActorMaterializer = ActorMaterializer()
//#server-bootstrapping
// needed for the future flatMap/onComplete in the end
implicit val executionContext = system.dispatcher
val responseFuture: Future[HttpResponse] = Http().singleRequest(HttpRequest(uri = "http://akka.io"))
responseFuture
.onComplete {
case Success(res) => println(res)
case Failure(_) => sys.error("something wrong")
}
}
How can I send a request and process the response every x time unit ?

Answer 1

A natural fit would be Akka Streams, on which Akka HTTP is built. The example below uses a repeating Source to make an HTTP request to a given URI every five seconds. The materialized stream prints the responses.
import akka.actor.ActorSystem
import akka.http.scaladsl.Http
import akka.http.scaladsl.model._
import akka.stream.ActorMaterializer
import akka.stream.scaladsl.Source
import scala.concurrent.duration._
object RestClient {
def main(args: Array[String]): Unit = {
implicit val materializer = ActorMaterializer()
Source
.repeat(HttpRequest(uri = "http://akka.io"))
.throttle(1, 5.seconds)
.mapAsync(1)(Http().singleRequest(_))
.runForeach(println)
}
}

Answer 2

you can define RestClient as an actor and use actorSystem.schedule to schedule the actor.
final def schedule(
initialDelay: FiniteDuration,
interval: FiniteDuration,
receiver: ActorRef,
message: Any)(implicit
executor: ExecutionContext,
sender: ActorRef = Actor.noSender): Cancellable =
Example,
import akka.actor.{Actor, ActorSystem, Props}
class RestClientActor extends Actor {
import RestClientActor._
import scala.util.Success
import scala.util.Failure
import akka.http.scaladsl.Http
import akka.http.scaladsl.model.HttpRequest
implicit val actorSystem: ActorSystem = context.system
import context.dispatcher
override def receive: Receive = {
case InitiateRequest =>
Http().singleRequest(HttpRequest(uri = "http://jsonplaceholder.typicode.com/posts")).onComplete {
case Success(s) => println(s._3)
case Failure(f) => println(f.getMessage)
}
}
}
object RestClientActor {
case object InitiateRequest
}
object RestClientApp {
def main(args: Array[String]): Unit = {
import akka.actor.ActorSystem
import scala.concurrent.duration._
import RestClientActor._
import scala.concurrent.ExecutionContextExecutor
implicit val system: ActorSystem = ActorSystem()
implicit val executionContext: ExecutionContextExecutor = system.dispatcher
val actor = system.actorOf(Props[RestClientActor], "RestClientActor")
system.scheduler.schedule(1 seconds, 3 seconds, actor, InitiateRequest)
}
}