Event Sourcing은 애플리케이션의 상태 변경을 일련의 이벤트로 저장하는 패턴이다. CQRS(Command Query Responsibility Segregation)는 명령(쓰기)과 쿼리(읽기)를 분리하는 패턴이다. 이 두 패턴을 결합하면 확장 가능하고 유연한 이벤트 기반 아키텍처를 구축할 수 있다.
\nEvent Sourcing은 다음과 같은 특징을 가진다:
\nCQRS는 다음과 같은 특징을 가진다:
\n| 구분 | \n전통적 방식 | \nEvent Sourcing + CQRS | \n
|---|---|---|
| 데이터 저장 | \n현재 상태만 저장 | \n모든 이벤트 저장 | \n
| 감사 추적 | \n별도 로그 필요 | \n이벤트가 감사 추적 | \n
| 읽기 성능 | \n단일 모델 | \n최적화된 읽기 모델 | \n
| 복잡도 | \n낮음 | \n높음 | \n
| 시간 여행 | \n불가능 | \n가능 | \n
| 이벤트 재처리 | \n불가능 | \n가능 | \n
// BaseEvent.java\npublic abstract class BaseEvent {\n private String aggregateId;\n private Long version;\n private LocalDateTime occurredAt;\n private String eventType;\n \n public BaseEvent(String aggregateId) {\n this.aggregateId = aggregateId;\n this.occurredAt = LocalDateTime.now();\n this.eventType = this.getClass().getSimpleName();\n }\n \n // getters and setters\n}\n\n// OrderCreatedEvent.java\npublic class OrderCreatedEvent extends BaseEvent {\n private String userId;\n private List<OrderItem> items;\n private BigDecimal totalAmount;\n \n public OrderCreatedEvent(String orderId, String userId, \n List<OrderItem> items, BigDecimal totalAmount) {\n super(orderId);\n this.userId = userId;\n this.items = items;\n this.totalAmount = totalAmount;\n }\n \n // getters and setters\n}\n\n// OrderPaidEvent.java\npublic class OrderPaidEvent extends BaseEvent {\n private String paymentId;\n private BigDecimal amount;\n private LocalDateTime paidAt;\n \n public OrderPaidEvent(String orderId, String paymentId, \n BigDecimal amount, LocalDateTime paidAt) {\n super(orderId);\n this.paymentId = paymentId;\n this.amount = amount;\n this.paidAt = paidAt;\n }\n \n // getters and setters\n}// Order.java (Aggregate Root)\npublic class Order {\n private String id;\n private String userId;\n private List<OrderItem> items;\n private BigDecimal totalAmount;\n private OrderStatus status;\n private Long version;\n private List<BaseEvent> uncommittedEvents = new ArrayList<>();\n \n // 이벤트로부터 Aggregate 재구성\n public static Order fromEvents(List<BaseEvent> events) {\n Order order = new Order();\n for (BaseEvent event : events) {\n order.apply(event);\n }\n return order;\n }\n \n // 이벤트 적용\n private void apply(BaseEvent event) {\n if (event instanceof OrderCreatedEvent) {\n apply((OrderCreatedEvent) event);\n } else if (event instanceof OrderPaidEvent) {\n apply((OrderPaidEvent) event);\n } else if (event instanceof OrderCancelledEvent) {\n apply((OrderCancelledEvent) event);\n }\n this.version = event.getVersion();\n }\n \n private void apply(OrderCreatedEvent event) {\n this.id = event.getAggregateId();\n this.userId = event.getUserId();\n this.items = event.getItems();\n this.totalAmount = event.getTotalAmount();\n this.status = OrderStatus.CREATED;\n }\n \n private void apply(OrderPaidEvent event) {\n this.status = OrderStatus.PAID;\n }\n \n private void apply(OrderCancelledEvent event) {\n this.status = OrderStatus.CANCELLED;\n }\n \n // 명령 처리\n public void create(String userId, List<OrderItem> items, BigDecimal totalAmount) {\n if (this.id != null) {\n throw new IllegalStateException(\"Order already created\");\n }\n \n OrderCreatedEvent event = new OrderCreatedEvent(\n UUID.randomUUID().toString(),\n userId,\n items,\n totalAmount\n );\n \n apply(event);\n uncommittedEvents.add(event);\n }\n \n public void pay(String paymentId, BigDecimal amount, LocalDateTime paidAt) {\n if (this.status != OrderStatus.CREATED) {\n throw new IllegalStateException(\"Order cannot be paid\");\n }\n \n OrderPaidEvent event = new OrderPaidEvent(\n this.id,\n paymentId,\n amount,\n paidAt\n );\n \n apply(event);\n uncommittedEvents.add(event);\n }\n \n public void cancel(String reason) {\n if (this.status == OrderStatus.PAID || this.status == OrderStatus.CANCELLED) {\n throw new IllegalStateException(\"Order cannot be cancelled\");\n }\n \n OrderCancelledEvent event = new OrderCancelledEvent(this.id, reason);\n apply(event);\n uncommittedEvents.add(event);\n }\n \n public List<BaseEvent> getUncommittedEvents() {\n return new ArrayList<>(uncommittedEvents);\n }\n \n public void markEventsAsCommitted() {\n uncommittedEvents.clear();\n }\n \n // getters\n}// EventStore.java\npublic interface EventStore {\n void saveEvents(String aggregateId, List<BaseEvent> events, Long expectedVersion);\n List<BaseEvent> getEvents(String aggregateId);\n List<BaseEvent> getEvents(String aggregateId, Long fromVersion);\n List<BaseEvent> getAllEvents();\n List<BaseEvent> getEventsByType(String eventType);\n}// EventEntity.java\n@Entity\n@Table(name = \"events\")\npublic class EventEntity {\n @Id\n private String id;\n \n @Column(nullable = false)\n private String aggregateId;\n \n @Column(nullable = false)\n private Long version;\n \n @Column(nullable = false)\n private String eventType;\n \n @Column(nullable = false, columnDefinition = \"TEXT\")\n private String eventData;\n \n @Column(nullable = false)\n private LocalDateTime occurredAt;\n \n // getters and setters\n}\n\n// JpaEventStore.java\n@Repository\npublic class JpaEventStore implements EventStore {\n \n @Autowired\n private EventRepository eventRepository;\n \n @Autowired\n private ObjectMapper objectMapper;\n \n @Override\n @Transactional\n public void saveEvents(String aggregateId, List<BaseEvent> events, Long expectedVersion) {\n // 낙관적 잠금 확인\n Long currentVersion = eventRepository.findMaxVersionByAggregateId(aggregateId)\n .orElse(0L);\n \n if (expectedVersion != null && !currentVersion.equals(expectedVersion)) {\n throw new ConcurrentModificationException(\n \"Expected version \" + expectedVersion + \" but was \" + currentVersion\n );\n }\n \n Long nextVersion = currentVersion;\n for (BaseEvent event : events) {\n nextVersion++;\n event.setVersion(nextVersion);\n \n EventEntity entity = new EventEntity();\n entity.setId(UUID.randomUUID().toString());\n entity.setAggregateId(aggregateId);\n entity.setVersion(nextVersion);\n entity.setEventType(event.getClass().getSimpleName());\n entity.setEventData(serializeEvent(event));\n entity.setOccurredAt(event.getOccurredAt());\n \n eventRepository.save(entity);\n }\n }\n \n @Override\n public List<BaseEvent> getEvents(String aggregateId) {\n List<EventEntity> entities = eventRepository\n .findByAggregateIdOrderByVersionAsc(aggregateId);\n return deserializeEvents(entities);\n }\n \n @Override\n public List<BaseEvent> getEvents(String aggregateId, Long fromVersion) {\n List<EventEntity> entities = eventRepository\n .findByAggregateIdAndVersionGreaterThanOrderByVersionAsc(aggregateId, fromVersion);\n return deserializeEvents(entities);\n }\n \n private String serializeEvent(BaseEvent event) {\n try {\n return objectMapper.writeValueAsString(event);\n } catch (JsonProcessingException e) {\n throw new RuntimeException(\"Failed to serialize event\", e);\n }\n }\n \n private BaseEvent deserializeEvent(EventEntity entity) {\n try {\n Class<?> eventClass = Class.forName(\n \"com.example.events.\" + entity.getEventType()\n );\n return (BaseEvent) objectMapper.readValue(\n entity.getEventData(),\n eventClass\n );\n } catch (Exception e) {\n throw new RuntimeException(\"Failed to deserialize event\", e);\n }\n }\n \n private List<BaseEvent> deserializeEvents(List<EventEntity> entities) {\n return entities.stream()\n .map(this::deserializeEvent)\n .collect(Collectors.toList());\n }\n}// OrderRepository.java\n@Repository\npublic class OrderRepository {\n \n @Autowired\n private EventStore eventStore;\n \n public Order findById(String orderId) {\n List<BaseEvent> events = eventStore.getEvents(orderId);\n if (events.isEmpty()) {\n return null;\n }\n return Order.fromEvents(events);\n }\n \n public void save(Order order) {\n List<BaseEvent> uncommittedEvents = order.getUncommittedEvents();\n if (!uncommittedEvents.isEmpty()) {\n Long expectedVersion = order.getVersion() - uncommittedEvents.size();\n eventStore.saveEvents(order.getId(), uncommittedEvents, expectedVersion);\n order.markEventsAsCommitted();\n }\n }\n}// CreateOrderCommand.java\npublic class CreateOrderCommand {\n private String userId;\n private List<OrderItem> items;\n private BigDecimal totalAmount;\n \n // getters and setters\n}\n\n// OrderCommandHandler.java\n@Component\npublic class OrderCommandHandler {\n \n @Autowired\n private OrderRepository orderRepository;\n \n @Autowired\n private EventPublisher eventPublisher;\n \n public String handle(CreateOrderCommand command) {\n Order order = new Order();\n order.create(\n command.getUserId(),\n command.getItems(),\n command.getTotalAmount()\n );\n \n orderRepository.save(order);\n \n // 이벤트 발행\n for (BaseEvent event : order.getUncommittedEvents()) {\n eventPublisher.publish(event);\n }\n \n return order.getId();\n }\n \n public void handle(PayOrderCommand command) {\n Order order = orderRepository.findById(command.getOrderId());\n if (order == null) {\n throw new OrderNotFoundException(command.getOrderId());\n }\n \n order.pay(\n command.getPaymentId(),\n command.getAmount(),\n LocalDateTime.now()\n );\n \n orderRepository.save(order);\n \n for (BaseEvent event : order.getUncommittedEvents()) {\n eventPublisher.publish(event);\n }\n }\n}// OrderReadModel.java\n@Entity\n@Table(name = \"order_read_model\")\npublic class OrderReadModel {\n @Id\n private String id;\n \n private String userId;\n \n @ElementCollection\n @CollectionTable(name = \"order_items_read\", joinColumns = @JoinColumn(name = \"order_id\"))\n private List<OrderItem> items;\n \n private BigDecimal totalAmount;\n \n @Enumerated(EnumType.STRING)\n private OrderStatus status;\n \n private LocalDateTime createdAt;\n private LocalDateTime paidAt;\n \n // getters and setters\n}\n\n// OrderReadRepository.java\n@Repository\npublic interface OrderReadRepository extends JpaRepository<OrderReadModel, String> {\n List<OrderReadModel> findByUserId(String userId);\n List<OrderReadModel> findByStatus(OrderStatus status);\n List<OrderReadModel> findByCreatedAtBetween(LocalDateTime start, LocalDateTime end);\n}// OrderReadModelUpdater.java\n@Component\npublic class OrderReadModelUpdater {\n \n @Autowired\n private OrderReadRepository readRepository;\n \n @EventListener\n public void handle(OrderCreatedEvent event) {\n OrderReadModel readModel = new OrderReadModel();\n readModel.setId(event.getAggregateId());\n readModel.setUserId(event.getUserId());\n readModel.setItems(event.getItems());\n readModel.setTotalAmount(event.getTotalAmount());\n readModel.setStatus(OrderStatus.CREATED);\n readModel.setCreatedAt(event.getOccurredAt());\n \n readRepository.save(readModel);\n }\n \n @EventListener\n public void handle(OrderPaidEvent event) {\n OrderReadModel readModel = readRepository.findById(event.getAggregateId())\n .orElseThrow(() -> new OrderNotFoundException(event.getAggregateId()));\n \n readModel.setStatus(OrderStatus.PAID);\n readModel.setPaidAt(event.getPaidAt());\n \n readRepository.save(readModel);\n }\n \n @EventListener\n public void handle(OrderCancelledEvent event) {\n OrderReadModel readModel = readRepository.findById(event.getAggregateId())\n .orElseThrow(() -> new OrderNotFoundException(event.getAggregateId()));\n \n readModel.setStatus(OrderStatus.CANCELLED);\n \n readRepository.save(readModel);\n }\n}// OrderQueryService.java\n@Service\npublic class OrderQueryService {\n \n @Autowired\n private OrderReadRepository readRepository;\n \n public OrderReadModel getOrder(String orderId) {\n return readRepository.findById(orderId)\n .orElseThrow(() -> new OrderNotFoundException(orderId));\n }\n \n public List<OrderReadModel> getOrdersByUser(String userId) {\n return readRepository.findByUserId(userId);\n }\n \n public List<OrderReadModel> getOrdersByStatus(OrderStatus status) {\n return readRepository.findByStatus(status);\n }\n \n public List<OrderReadModel> getOrdersByDateRange(\n LocalDateTime start,\n LocalDateTime end\n ) {\n return readRepository.findByCreatedAtBetween(start, end);\n }\n}// Snapshot.java\n@Entity\n@Table(name = \"snapshots\")\npublic class Snapshot {\n @Id\n private String id;\n \n @Column(nullable = false)\n private String aggregateId;\n \n @Column(nullable = false)\n private Long version;\n \n @Column(nullable = false, columnDefinition = \"TEXT\")\n private String snapshotData;\n \n @Column(nullable = false)\n private LocalDateTime createdAt;\n \n // getters and setters\n}\n\n// SnapshotRepository.java\n@Repository\npublic interface SnapshotRepository extends JpaRepository<Snapshot, String> {\n Optional<Snapshot> findTopByAggregateIdOrderByVersionDesc(String aggregateId);\n}\n\n// SnapshotService.java\n@Service\npublic class SnapshotService {\n \n @Autowired\n private SnapshotRepository snapshotRepository;\n \n @Autowired\n private EventStore eventStore;\n \n @Autowired\n private ObjectMapper objectMapper;\n \n private static final int SNAPSHOT_INTERVAL = 100; // 100개 이벤트마다 스냅샷\n \n public void saveSnapshot(String aggregateId, Order order) {\n if (order.getVersion() % SNAPSHOT_INTERVAL == 0) {\n Snapshot snapshot = new Snapshot();\n snapshot.setId(UUID.randomUUID().toString());\n snapshot.setAggregateId(aggregateId);\n snapshot.setVersion(order.getVersion());\n snapshot.setSnapshotData(serializeOrder(order));\n snapshot.setCreatedAt(LocalDateTime.now());\n \n snapshotRepository.save(snapshot);\n }\n }\n \n public Order loadFromSnapshot(String aggregateId) {\n Optional<Snapshot> snapshotOpt = snapshotRepository\n .findTopByAggregateIdOrderByVersionDesc(aggregateId);\n \n if (snapshotOpt.isPresent()) {\n Snapshot snapshot = snapshotOpt.get();\n Order order = deserializeOrder(snapshot.getSnapshotData());\n \n // 스냅샷 이후의 이벤트 로드\n List<BaseEvent> events = eventStore.getEvents(\n aggregateId,\n snapshot.getVersion()\n );\n \n // 이벤트 적용\n for (BaseEvent event : events) {\n order.apply(event);\n }\n \n return order;\n } else {\n // 스냅샷이 없으면 모든 이벤트 로드\n List<BaseEvent> events = eventStore.getEvents(aggregateId);\n return Order.fromEvents(events);\n }\n }\n \n private String serializeOrder(Order order) {\n try {\n return objectMapper.writeValueAsString(order);\n } catch (JsonProcessingException e) {\n throw new RuntimeException(\"Failed to serialize order\", e);\n }\n }\n \n private Order deserializeOrder(String data) {\n try {\n return objectMapper.readValue(data, Order.class);\n } catch (JsonProcessingException e) {\n throw new RuntimeException(\"Failed to deserialize order\", e);\n }\n }\n}// EventPublisher.java\n@Component\npublic class EventPublisher {\n \n private final ApplicationEventPublisher applicationEventPublisher;\n \n public EventPublisher(ApplicationEventPublisher applicationEventPublisher) {\n this.applicationEventPublisher = applicationEventPublisher;\n }\n \n public void publish(BaseEvent event) {\n applicationEventPublisher.publishEvent(event);\n }\n \n public void publishAll(List<BaseEvent> events) {\n for (BaseEvent event : events) {\n publish(event);\n }\n }\n}// KafkaEventPublisher.java\n@Component\npublic class KafkaEventPublisher {\n \n @Autowired\n private KafkaTemplate<String, Object> kafkaTemplate;\n \n @EventListener\n @Async\n public void handle(BaseEvent event) {\n String topic = \"domain-events\";\n kafkaTemplate.send(topic, event.getAggregateId(), event);\n }\n}// InventoryEventHandler.java\n@Component\npublic class InventoryEventHandler {\n \n @Autowired\n private InventoryService inventoryService;\n \n @EventListener\n @Async\n public void handle(OrderCreatedEvent event) {\n // 재고 차감\n for (OrderItem item : event.getItems()) {\n inventoryService.decreaseStock(\n item.getProductId(),\n item.getQuantity()\n );\n }\n }\n \n @EventListener\n @Async\n public void handle(OrderCancelledEvent event) {\n // 재고 복구\n Order order = loadOrder(event.getAggregateId());\n for (OrderItem item : order.getItems()) {\n inventoryService.increaseStock(\n item.getProductId(),\n item.getQuantity()\n );\n }\n }\n}\n\n// NotificationEventHandler.java\n@Component\npublic class NotificationEventHandler {\n \n @Autowired\n private NotificationService notificationService;\n \n @EventListener\n @Async\n public void handle(OrderCreatedEvent event) {\n notificationService.sendOrderConfirmation(event.getUserId(), event.getAggregateId());\n }\n \n @EventListener\n @Async\n public void handle(OrderPaidEvent event) {\n Order order = loadOrder(event.getAggregateId());\n notificationService.sendPaymentConfirmation(order.getUserId(), event.getAggregateId());\n }\n}// EventSourcingConfig.java\n@Configuration\n@EnableAsync\npublic class EventSourcingConfig {\n \n @Bean\n public ObjectMapper objectMapper() {\n ObjectMapper mapper = new ObjectMapper();\n mapper.registerModule(new JavaTimeModule());\n mapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);\n return mapper;\n }\n \n @Bean\n public TaskExecutor eventTaskExecutor() {\n ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();\n executor.setCorePoolSize(5);\n executor.setMaxPoolSize(10);\n executor.setQueueCapacity(100);\n executor.setThreadNamePrefix(\"event-handler-\");\n executor.initialize();\n return executor;\n }\n}// OrderController.java\n@RestController\n@RequestMapping(\"/api/orders\")\npublic class OrderController {\n \n @Autowired\n private OrderCommandHandler commandHandler;\n \n @Autowired\n private OrderQueryService queryService;\n \n @PostMapping\n public ResponseEntity<OrderResponse> createOrder(@RequestBody CreateOrderRequest request) {\n CreateOrderCommand command = new CreateOrderCommand();\n command.setUserId(request.getUserId());\n command.setItems(request.getItems());\n command.setTotalAmount(request.getTotalAmount());\n \n String orderId = commandHandler.handle(command);\n \n OrderReadModel order = queryService.getOrder(orderId);\n return ResponseEntity.ok(toResponse(order));\n }\n \n @PostMapping(\"/{orderId}/pay\")\n public ResponseEntity<Void> payOrder(\n @PathVariable String orderId,\n @RequestBody PayOrderRequest request\n ) {\n PayOrderCommand command = new PayOrderCommand();\n command.setOrderId(orderId);\n command.setPaymentId(request.getPaymentId());\n command.setAmount(request.getAmount());\n \n commandHandler.handle(command);\n \n return ResponseEntity.ok().build();\n }\n \n @GetMapping(\"/{orderId}\")\n public ResponseEntity<OrderResponse> getOrder(@PathVariable String orderId) {\n OrderReadModel order = queryService.getOrder(orderId);\n return ResponseEntity.ok(toResponse(order));\n }\n \n @GetMapping\n public ResponseEntity<List<OrderResponse>> getOrders(\n @RequestParam(required = false) String userId,\n @RequestParam(required = false) OrderStatus status\n ) {\n List<OrderReadModel> orders;\n if (userId != null) {\n orders = queryService.getOrdersByUser(userId);\n } else if (status != null) {\n orders = queryService.getOrdersByStatus(status);\n } else {\n orders = queryService.getAllOrders();\n }\n \n List<OrderResponse> responses = orders.stream()\n .map(this::toResponse)\n .collect(Collectors.toList());\n \n return ResponseEntity.ok(responses);\n }\n \n private OrderResponse toResponse(OrderReadModel order) {\n OrderResponse response = new OrderResponse();\n response.setId(order.getId());\n response.setUserId(order.getUserId());\n response.setItems(order.getItems());\n response.setTotalAmount(order.getTotalAmount());\n response.setStatus(order.getStatus());\n response.setCreatedAt(order.getCreatedAt());\n return response;\n }\n}// OrderCreatedEventV2.java\npublic class OrderCreatedEventV2 extends BaseEvent {\n private String userId;\n private List<OrderItem> items;\n private BigDecimal totalAmount;\n private String shippingAddress; // 새 필드 추가\n \n // getters and setters\n}\n\n// 이벤트 업그레이드\n@Component\npublic class EventUpgrader {\n \n public BaseEvent upgrade(BaseEvent event) {\n if (event instanceof OrderCreatedEvent && \n event.getVersion() < 2) {\n // V1을 V2로 업그레이드\n OrderCreatedEvent v1 = (OrderCreatedEvent) event;\n OrderCreatedEventV2 v2 = new OrderCreatedEventV2(\n v1.getAggregateId(),\n v1.getUserId(),\n v1.getItems(),\n v1.getTotalAmount(),\n \"\" // 기본값\n );\n v2.setVersion(2L);\n return v2;\n }\n return event;\n }\n}// OrderedEventStore.java\n@Component\npublic class OrderedEventStore {\n \n @Autowired\n private EventStore eventStore;\n \n @Autowired\n private RedisTemplate<String, String> redisTemplate;\n \n public void saveEvents(String aggregateId, List<BaseEvent> events, Long expectedVersion) {\n String lockKey = \"lock:\" + aggregateId;\n \n // 분산 락 획득\n Boolean locked = redisTemplate.opsForValue()\n .setIfAbsent(lockKey, \"locked\", Duration.ofSeconds(10));\n \n if (!locked) {\n throw new ConcurrentModificationException(\"Failed to acquire lock\");\n }\n \n try {\n eventStore.saveEvents(aggregateId, events, expectedVersion);\n } finally {\n redisTemplate.delete(lockKey);\n }\n }\n}// EventReplayService.java\n@Service\npublic class EventReplayService {\n \n @Autowired\n private EventStore eventStore;\n \n @Autowired\n private OrderReadModelUpdater readModelUpdater;\n \n @Autowired\n private OrderReadRepository readRepository;\n \n public void replayEvents(String aggregateId) {\n // 읽기 모델 삭제\n readRepository.deleteById(aggregateId);\n \n // 이벤트 재생\n List<BaseEvent> events = eventStore.getEvents(aggregateId);\n for (BaseEvent event : events) {\n readModelUpdater.handle(event);\n }\n }\n \n public void replayAllEvents() {\n List<BaseEvent> allEvents = eventStore.getAllEvents();\n \n // 읽기 모델 전체 삭제\n readRepository.deleteAll();\n \n // 이벤트 재생\n for (BaseEvent event : allEvents) {\n readModelUpdater.handle(event);\n }\n }\n}// LoggingEventHandler.java\n@Component\npublic class LoggingEventHandler {\n \n private static final Logger logger = LoggerFactory.getLogger(\n LoggingEventHandler.class);\n \n @EventListener\n public void handle(BaseEvent event) {\n logger.info(\"Event occurred: {} for aggregate: {} at version: {}\",\n event.getEventType(),\n event.getAggregateId(),\n event.getVersion());\n }\n}// MetricsEventHandler.java\n@Component\npublic class MetricsEventHandler {\n \n private final Counter eventCounter;\n private final Timer eventProcessingTime;\n \n public MetricsEventHandler(MeterRegistry meterRegistry) {\n this.eventCounter = Counter.builder(\"events.total\")\n .description(\"Total number of events\")\n .register(meterRegistry);\n \n this.eventProcessingTime = Timer.builder(\"events.processing.time\")\n .description(\"Event processing time\")\n .register(meterRegistry);\n }\n \n @EventListener\n public void handle(BaseEvent event) {\n eventCounter.increment(\n Tags.of(\"type\", event.getEventType())\n );\n }\n}Event Sourcing과 CQRS는 복잡하지만 강력한 아키텍처 패턴이다. 이 글에서 다룬 내용:
\n이러한 패턴들을 적절히 활용하면 확장 가능하고 유연한 이벤트 기반 시스템을 구축할 수 있다.
\nEvent Sourcing과 CQRS 패턴 - 이벤트 기반 아키텍처 설계 실전 가이드
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