temp; sse-tutorial 코드를 작성해요

_endpoint_test/notification-sse.http

@@ -0,0 +1,7 @@
+### emitter 연결(조회)
+GET {{host}}/test/event-stream
+Authorization: {{authorization}}
+
+### 알림 전송
+POST {{host}}/notification?message=hello~5
+Authorization: {{authorization}}

api/src/main/kotlin/com/mashup/dojo/NotificationSseController.kt

@@ -0,0 +1,49 @@
+package com.mashup.dojo
+
+import io.github.oshai.kotlinlogging.KotlinLogging
+import org.springframework.web.bind.annotation.GetMapping
+import org.springframework.web.bind.annotation.PostMapping
+import org.springframework.web.bind.annotation.RestController
+import org.springframework.web.servlet.mvc.method.annotation.SseEmitter
+import java.util.concurrent.CopyOnWriteArrayList
+
+@RestController
+class NotificationSseController {
+    private val emitters = CopyOnWriteArrayList<SseEmitter>()
+    private val logger = KotlinLogging.logger { }
+
+    private fun addEmitter(emitter: SseEmitter) {
+        emitters.add(emitter)
+        emitter.onCompletion {
+            logger.debug { "emitter completed successfully" }
+            emitters.remove(emitter)
+        }
+        emitter.onError {
+            logger.debug { "emitter error occurred: $it" }
+            emitters.remove(emitter)
+        }
+        emitter.onTimeout {
+            logger.debug { "emitter timed out" }
+            emitters.remove(emitter)
+        }
+    }
+
+    @PostMapping("/notification")
+    fun send(message: String) {
+        emitters.forEach {
+            kotlin.runCatching {
+                it.send(SseEmitter.event().name("notification-test").data(message))
+            }.onFailure {
+                logger.error { "error occurred: $it" }
+            }
+        }
+    }
+
+    @GetMapping("/test/event-stream")
+    fun test(): SseEmitter {
+        // timeout 동안 아무런 데이터 전송되지 않으면 연결 자동 종료
+        val emitter = SseEmitter(180000L)
+        addEmitter(emitter)
+        return emitter
+    }
+}