액터에게 이벤트를 보낸후 응답값을 수신 받으려면 REST에서는 그 결과를 대기해야 합니다.
공식적으로는 ASK패턴으로 액터에게 메시지를 보내는 패턴은 크게는 두가지가 있습니다.
- tell : send이후 응답값이 없어 just tell하는 경우
- ask : send이후 응답값을 대기하는경우
자바가 기본 제공하는 CompletionStage가 맘에 안들기도 해서, ASK 패턴을 4가지 방식을 이용하는 코드를 작성 코르틴을 위한 유틸 클래스도 생성
Akka HTTP를 사용하면 더 심플하게 이용할수 있지만 코프링기반에 취향에 맞는 방식으로 통일할수 있습니다.
- CompletionStage
- AkkaStream
- Async ( 코르틴 )
- Mono ( WebFlux )
@RestController
@RequestMapping("/api/admin/channel")
class AdminChannelController(private val actorSystem: ActorSystem<MainStageActorCommand>,
private val supervisorChannelActor: ActorRef<SupervisorChannelCommand>) {
private val timeout: Duration = Duration.ofSeconds(5)
@PostMapping("/add-counselor-manager")
fun addCounselorManager(@RequestParam channel: String): CompletionStage<String>? {
return AskPattern.ask(
supervisorChannelActor,
{ replyTo: ActorRef<SupervisorChannelResponse> -> CreateCounselorManager(channel, replyTo) },
timeout,
actorSystem.scheduler()
).thenApply { response ->
when (response) {
is CounselorManagerCreated -> "Counselor Manager for channel $channel created successfully."
is SupervisorErrorStringResponse -> response.message
else -> "Unknown error occurred."
}
}
}
@GetMapping("/list-counselor-managers")
fun listCounselorManagers(): CompletionStage<List<String>>? {
return AskPattern.ask(
supervisorChannelActor,
{ replyTo: ActorRef<SupervisorChannelResponse> -> GetAllCounselorManagers(replyTo) },
timeout,
actorSystem.scheduler()
).thenApply { response ->
when (response) {
is AllCounselorManagers -> response.channels
else -> emptyList()
}
}
}
@GetMapping("/list-counselor-managers-stream")
fun listCounselorManagersByStream(): CompletionStage<List<String>> {
return Source.single(Unit)
.mapAsync(1) {
AskPattern.ask(
supervisorChannelActor,
{ replyTo: ActorRef<SupervisorChannelResponse> -> GetAllCounselorManagers(replyTo) },
timeout,
actorSystem.scheduler()
)
}
.runWith(Sink.head(), actorSystem)
.thenApply { response ->
when (response) {
is AllCounselorManagers -> response.channels
else -> emptyList()
}
}
}
@GetMapping("/list-counselor-managers-async")
fun listCounselorManagersByCoroutines(): List<String> {
val response = AkkaUtils.runBlockingAsk(
supervisorChannelActor,
{ replyTo: ActorRef<SupervisorChannelResponse> -> GetAllCounselorManagers(replyTo) },
timeout, actorSystem
)
return when (response) {
is AllCounselorManagers -> response.channels
else -> emptyList()
}
}
@GetMapping("/list-counselor-managers-mono")
fun listCounselorManagersByMono(): Mono<List<String>> {
return AkkaUtils.askActorByMono(
supervisorChannelActor,
{ replyTo: ActorRef<SupervisorChannelResponse> -> GetAllCounselorManagers(replyTo) },
timeout,
actorSystem
).map { response ->
when (response) {
is AllCounselorManagers -> response.channels
else -> emptyList()
}
}
}
- 더 줄이고 싶지만 여기까지
package com.example.kotlinbootlabs.module
import akka.actor.typed.ActorRef
import akka.actor.typed.ActorSystem
import akka.actor.typed.javadsl.AskPattern
import java.time.Duration
import kotlinx.coroutines.future.await
import kotlinx.coroutines.runBlocking
object AkkaUtils {
suspend fun <T, R> askActor(
actor: ActorRef<T>,
message: (ActorRef<R>) -> T,
timeout: Duration,
actorSystem: ActorSystem<*>
): R {
return AskPattern.ask(
actor,
message,
timeout,
actorSystem.scheduler()
).await()
}
fun <T, R> runBlockingAsk(
actor: ActorRef<T>,
message: (ActorRef<R>) -> T,
timeout: Duration,
actorSystem: ActorSystem<*>
): R = runBlocking {
askActor(actor, message, timeout, actorSystem)
}
fun <T, R> askActorByMono(
actor: ActorRef<T>,
message: (ActorRef<R>) -> T,
timeout: Duration,
actorSystem: ActorSystem<*>
): Mono<R> {
return Mono.fromCompletionStage(
AskPattern.ask(
actor,
message,
timeout,
actorSystem.scheduler()
)
)
}
}
- AKKA가 Scala/JAVA만 기본으로 지원하고 Kotlin은 알아서 호환해야하다보니, 자바코드에서 오는 괴리감을 이 유틸 클래스가 처리해주는것으로
액터는 기본으로 기본언어가 가진 동시성 처리 스펙을 활용함으로, 액터이용에 앞서 기본언어가 지원하는 비동기 프로그래밍 방식을 먼저 학습할 필요가 있습니다.