Brief introduction to back-pressure and Akka Streams

backpressure.scala

//imports

object MyBackPressureTest extends App {

  implicit val system = ActorSystem()
  implicit val materializer = ActorMaterializer()
  
  val addresses = List(Address...) //a list of some addresses
  
  val createRequestFlow = Flow[Address].map { address =>
    val params = Map("state" -> address.state, "city" -> address.city, "street" -> address.street)
    val uri = Uri("/geocode").withQuery(Uri.Query(params))
    HttpRequest(uri = uri) -> address
  }
  
  val httpFlow = Http().cachedHostConnectionPool[Adress](host = "my-api.company.com", port = 80)
  
  val responseFlow = Flow[(Try[HttpResponse], Address)].map { tuple =>
    val (responseTry, address) = tuple
    //here you can deal with the http response
  }
  
  Source(addresses)
    .via(createRequestFlow)
    .via(httpFlow)
    .via(responseFlow)
    .toMat(Sink.ignore)(Keep.right)
    .run()
}

case class Address(state: String, city: String, street: String)