Feat: 채팅 WebSocket Redis Pub/Sub 연동 및 구조 개선

src/main/java/jpa/basic/alldayprojectcommerce/common/config/RedisConfig.java

@@ -1,9 +1,16 @@
 package jpa.basic.alldayprojectcommerce.common.config;
 
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.databind.SerializationFeature;
+import com.fasterxml.jackson.datatype.jsr310.JavaTimeModule;
+import jpa.basic.alldayprojectcommerce.domain.chat.redis.ChatRedisSubscriber;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.data.redis.connection.RedisConnectionFactory;
 import org.springframework.data.redis.core.RedisTemplate;
+import org.springframework.data.redis.listener.PatternTopic;
+import org.springframework.data.redis.listener.RedisMessageListenerContainer;
+import org.springframework.data.redis.serializer.GenericJackson2JsonRedisSerializer;
 import org.springframework.data.redis.serializer.StringRedisSerializer;
 
 @Configuration
@@ -23,4 +30,62 @@ public RedisTemplate<String, String> redisTemplate(RedisConnectionFactory factor
 
         return template;
     }
+
+    /**
+     * 채팅 Pub/Sub용 RedisTemplate (JSON 직렬화)
+     *
+     * ChatMessageResponse 객체를 JSON으로 직렬화하여 Redis 채널에 발행
+     * StringRedisSerializer로는 객체 직렬화 불가 -> Jackson 기반 JSON 직렬화 사용
+     */
+    @Bean
+    public RedisTemplate<String, Object> chatRedisTemplate(RedisConnectionFactory factory) {
+        RedisTemplate<String, Object> template = new RedisTemplate<>();
+        template.setConnectionFactory(factory);
+
+        /**
+         * JavaTimeModule 등록한 ObjectMapper 설정
+         * LocalDateTime 등 Java 8 날짜 타입 직렬화 지원
+         */
+        ObjectMapper objectMapper = new ObjectMapper();
+        objectMapper.registerModule(new JavaTimeModule());
+        objectMapper.disable(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS);
+        // 타입 정보 포함 - 역직렬화 시 올바른 클래스로 복원
+        objectMapper.activateDefaultTyping(
+                objectMapper.getPolymorphicTypeValidator(),
+                ObjectMapper.DefaultTyping.NON_FINAL
+        );
+
+        GenericJackson2JsonRedisSerializer serializer =
+                new GenericJackson2JsonRedisSerializer(objectMapper);
+
+        StringRedisSerializer keySerializer = new StringRedisSerializer();
+        template.setKeySerializer(keySerializer);
+        template.setValueSerializer(serializer);
+        template.setHashKeySerializer(keySerializer);
+        template.setHashValueSerializer(serializer);
+
+        return template;
+    }
+
+    /**
+     * Redis Pub/Sub 메시지 리스터 컨테이너
+     *
+     * PatternTopic("chat:room:*")
+     * "chat:room:1", "chat:room:2" 등 모든 채팅방 채널을 단일 리스너로 처리
+     */
+    @Bean
+    public RedisMessageListenerContainer redisMessageListenerContainer(
+            RedisConnectionFactory redisConnectionFactory,
+            ChatRedisSubscriber chatRedisSubscriber) {
+
+        RedisMessageListenerContainer container = new RedisMessageListenerContainer();
+        container.setConnectionFactory(redisConnectionFactory);
+
+        // "chat:room:*" - 모든 채팅방 채널을 단일 리스너로 처리
+        container.addMessageListener(chatRedisSubscriber,
+                new PatternTopic("chat:room:*")
+        );
+
+        return container;
+    }
 }

src/main/java/jpa/basic/alldayprojectcommerce/common/config/StompChannelInterceptor.java

@@ -59,6 +59,19 @@ public Message<?> preSend(Message<?> message, MessageChannel channel) {
             log.info("[STOMP] 연결 성공 userId: {}, role: {}", userId, role);
         }
 
+        /**
+         * SUBSCRIBE 시점 - 구독 경로 권한 검증
+         *
+         * /sub/chat/{roomId} 구독 시 해당 방에 접근 권한이 있는지 확인
+         * 지금은 인증된 유저만 구독 가능하도록 1차 방어
+         */
+        if (StompCommand.SUBSCRIBE.equals(accessor.getCommand())) {
+            if (!(accessor.getUser() instanceof StompPrincipal)) {
+                log.warn("[STOMP] 인증되지 않은 구독 시도 차단");
+                throw new CustomException(ErrorCode.CHAT_UNAUTHORIZED);
+            }
+        }
+
         return message;
     }
 

src/main/java/jpa/basic/alldayprojectcommerce/common/config/WebSocketConfig.java

@@ -28,8 +28,9 @@ public class WebSocketConfig implements WebSocketMessageBrokerConfigurer {
      */
     @Override
     public void configureMessageBroker(MessageBrokerRegistry registry) {
-        registry.enableSimpleBroker("/sub");    // 구독 경로  prefix
-        registry.setApplicationDestinationPrefixes("/pub");      // 발행 경로  prefix
+        registry.enableSimpleBroker("/sub", "/queue");    // 구독 경로  prefix
+        registry.setApplicationDestinationPrefixes("/pub");                // 발행 경로  prefix
+        registry.setUserDestinationPrefix("/user");                        // 개인 세션 라우팅 prefix
     }
 
     /**

src/main/java/jpa/basic/alldayprojectcommerce/common/exception/WebSocketExceptionHandler.java

@@ -0,0 +1,38 @@
+package jpa.basic.alldayprojectcommerce.common.exception;
+
+import jpa.basic.alldayprojectcommerce.domain.chat.dto.response.ChatErrorResponse;
+import lombok.extern.slf4j.Slf4j;
+import org.springframework.messaging.handler.annotation.MessageExceptionHandler;
+import org.springframework.messaging.simp.annotation.SendToUser;
+import org.springframework.web.bind.annotation.ControllerAdvice;
+
+@Slf4j
+@ControllerAdvice
+public class WebSocketExceptionHandler {
+
+    /**
+     * WebSocket 전용 전역 예외 처리기
+     *
+     * 에러 응답 경로: /user/queue/errors
+     * 예외 발생한 당사자 세션에만 전송
+     * 클라이언트: SUBSCRIBE /user/queue/errors 구독 필요
+     */
+    @MessageExceptionHandler(CustomException.class)
+    @SendToUser("/queue/errors")
+    public ChatErrorResponse handleCustomException(CustomException e) {
+        log.warn("[WebSocket] 비즈니스 예외 - {}: {}", e.getErrorCode().getCode(), e.getErrorCode().getMessage());
+
+        return new ChatErrorResponse(
+                e.getErrorCode().getCode(),
+                e.getErrorCode().getMessage()
+        );
+    }
+
+    @MessageExceptionHandler(Exception.class)
+    @SendToUser("/queue/errors")
+    public ChatErrorResponse handleUnexpectedException(Exception e) {
+        log.error("[WebSocket] 예상치 못한 예외", e);
+
+        return new ChatErrorResponse("SYS001", "서버 내부 오류가 발생했습니다.");
+    }
+}

src/main/java/jpa/basic/alldayprojectcommerce/domain/chat/controller/ChatWebSocketController.java

@@ -0,0 +1,72 @@
+package jpa.basic.alldayprojectcommerce.domain.chat.controller;
+
+import jakarta.validation.Valid;
+import jpa.basic.alldayprojectcommerce.common.config.StompPrincipal;
+import jpa.basic.alldayprojectcommerce.common.exception.CustomException;
+import jpa.basic.alldayprojectcommerce.common.exception.ErrorCode;
+import jpa.basic.alldayprojectcommerce.domain.chat.dto.request.ChatMessageRequest;
+import jpa.basic.alldayprojectcommerce.domain.chat.dto.response.ChatMessageResponse;
+import jpa.basic.alldayprojectcommerce.domain.chat.redis.ChatRedisPublisher;
+import jpa.basic.alldayprojectcommerce.domain.chat.service.ChatMessageService;
+import lombok.RequiredArgsConstructor;
+import lombok.extern.slf4j.Slf4j;
+import org.springframework.messaging.handler.annotation.DestinationVariable;
+import org.springframework.messaging.handler.annotation.MessageExceptionHandler;
+import org.springframework.messaging.handler.annotation.MessageMapping;
+import org.springframework.messaging.simp.SimpMessagingTemplate;
+import org.springframework.messaging.simp.annotation.SendToUser;
+import org.springframework.stereotype.Controller;
+
+import java.security.Principal;
+
+@Slf4j
+@Controller
+@RequiredArgsConstructor
+public class ChatWebSocketController {
+
+    private final ChatMessageService chatMessageService;
+    private final ChatRedisPublisher chatRedisPublisher;
+
+    /**
+     * 클라이언트 -> 서버: 메시지 전송
+     *
+     * chatRedisPublisher.publish(roomId, response)
+     *  1. Redis 채널에 발행
+     *  2. 모든 서버의 ChatRedisSubscriber가 수신
+     *  3. 각 서버가 자기 WebSocket 구독자에게 브로드캐스트
+     *  4. 서버 A/B 어디 접속한 구독자든 메시지 수신 가능
+     */
+    @MessageMapping("/chat/{roomId}")
+    public void sendMessage(
+            @DestinationVariable Long roomId,
+            @Valid ChatMessageRequest request,
+            Principal principal) {
+
+        if (!(principal instanceof StompPrincipal stompUser)) {
+            log.warn("[WebSocket] Principal이 StompPrincipal이 아님 - 비정상");
+            throw new CustomException(ErrorCode.CHAT_UNAUTHORIZED);
+        }
+
+        Long senderId = stompUser.getUserId();
+        String role = stompUser.getRole();
+
+        /**
+         * 메시지 저장 + 권한 검증
+         *
+         * 검증 실패 시 클라이언트에 STOMP ERROR 프레임 전송
+         */
+        ChatMessageResponse response =
+                chatMessageService.saveMessage(roomId, senderId, role, request);
+
+        /**
+         * Redis 채널에 발행
+         *
+         * 모든 서버의 구독자에게 브로드캐스트
+         */
+
+        chatRedisPublisher.publish(roomId, response);
+
+        log.debug("[WebSocket] 메시지 발행 roomId: {}, messageId: {}",
+                                                roomId, response.id());
+    }
+}

src/main/java/jpa/basic/alldayprojectcommerce/domain/chat/dto/response/ChatErrorResponse.java

@@ -0,0 +1,6 @@
+package jpa.basic.alldayprojectcommerce.domain.chat.dto.response;
+
+public record ChatErrorResponse(
+        String code, String message
+) {
+}

src/main/java/jpa/basic/alldayprojectcommerce/domain/chat/redis/ChatRedisPublisher.java

@@ -0,0 +1,27 @@
+package jpa.basic.alldayprojectcommerce.domain.chat.redis;
+
+import jpa.basic.alldayprojectcommerce.domain.chat.dto.response.ChatMessageResponse;
+import lombok.RequiredArgsConstructor;
+import lombok.extern.slf4j.Slf4j;
+import org.springframework.data.redis.core.RedisTemplate;
+import org.springframework.stereotype.Component;
+
+@Slf4j
+@Component
+@RequiredArgsConstructor
+public class ChatRedisPublisher {
+
+    private final RedisTemplate<String, Object> chatRedisTemplate;
+
+    /**
+     * Redis 채널에 채팅 메시지 발행
+     *
+     * 채널명: "chat:room:{roomId}"
+     * 모든 서버의 ChatRedisSubscriber가 이 채널을 구독 중
+     */
+    public void publish(Long roomId, ChatMessageResponse message) {
+        String channel = "chat:room:" + roomId;
+        chatRedisTemplate.convertAndSend(channel, message);
+        log.debug("[Redis Pub] channel: {}, messageId: {}", channel, message.id());
+    }
+}

src/main/java/jpa/basic/alldayprojectcommerce/domain/chat/redis/ChatRedisSubscriber.java

@@ -0,0 +1,49 @@
+package jpa.basic.alldayprojectcommerce.domain.chat.redis;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+import jpa.basic.alldayprojectcommerce.domain.chat.dto.response.ChatMessageResponse;
+import lombok.RequiredArgsConstructor;
+import lombok.extern.slf4j.Slf4j;
+import org.jspecify.annotations.Nullable;
+import org.springframework.data.redis.connection.Message;
+import org.springframework.data.redis.connection.MessageListener;
+import org.springframework.messaging.simp.SimpMessagingTemplate;
+import org.springframework.stereotype.Component;
+
+@Slf4j
+@Component
+@RequiredArgsConstructor
+public class ChatRedisSubscriber implements MessageListener {
+
+    private final SimpMessagingTemplate simpMessagingTemplate;
+    private final ObjectMapper objectMapper;
+
+    /**
+     * Redis 채널 메시지 수신 -> WebSocket 브로드캐스트
+     *
+     * 흐름:
+     * 1. 어떤 서버에서든 "chat:room:{roomId}" 채널에 발행
+     * 2. 모든 서버의 이 메서드가 호출됨
+     * 3. 각 서버는 자신이 보유한 WebSocket 구독자에게 브로드캐스트
+     *
+     * "chat:room:".length() = 10 이후 문자열이 roomId
+     */
+    @Override
+    public void onMessage(Message message, @Nullable byte[] pattern) {
+        try {
+            String channel = new String(message.getChannel());
+            String roomId = channel.substring("chat:room:".length());
+
+            ChatMessageResponse response = objectMapper.readValue(
+                    message.getBody(), ChatMessageResponse.class);
+
+            // 구독자 전체에게 브로드캐스트
+            simpMessagingTemplate.convertAndSend("/sub/chat/" + roomId, response);
+
+            log.debug("[Redis Sub] roomId: {}, messageId: {}", roomId, response.id());
+
+        } catch (Exception e) {
+            log.error("[Redis Sub] 메시지 처리 실패", e);
+        }
+    }
+}