Olingo分析和实践——Delta 序列化器详解(第二部分: 高级应用)

1. 实时数据同步系统

在分布式系统中，Delta序列化器是实现实时数据同步的核心组件。

实时数据同步流程图

批量变更处理流程图

2. 微服务间数据一致性

在微服务架构中，使用Delta序列化器保持服务间数据一致性。

微服务数据同步架构图

冲突检测与解决流程图

Delta合并策略图

@Component
public class MicroserviceDataConsistencyManager {
    
    private final OData odata = OData.newInstance();
    private final RestTemplate restTemplate;
    private final KafkaTemplate<String, String> kafkaTemplate;
    
    /**
     * 跨服务数据同步
     */
    public class CrossServiceSyncManager {
        
        /**
         * 同步数据到下游服务
         */
        @EventListener
        public void handleDataChangeEvent(DataChangeEvent event) {
            try {
                // 构建Delta响应
                Delta delta = buildDeltaFromEvent(event);
                String deltaJson = serializeDelta(delta, event.getEntityType());
                
                // 发送到消息队列
                kafkaTemplate.send("data-sync-topic", event.getEntityType(), deltaJson);
                
                // 直接同步到关键服务
                List<String> criticalServices = getCriticalServices(event.getEntityType());
                for (String serviceUrl : criticalServices) {
                    syncToService(serviceUrl, deltaJson);
                }
                
            } catch (Exception e) {
                // 记录失败并加入重试队列
                handleSyncFailure(event, e);
            }
        }
        
        /**
         * 处理来自上游服务的Delta更新
         */
        @KafkaListener(topics = "data-sync-topic")
        public void handleUpstreamDelta(String deltaJson, 
                @Header("entity-type") String entityType) {
            
            try {
                // 解析Delta响应
                Delta delta = parseDeltaJson(deltaJson);
                
                // 应用变更到本地数据库
                applyDeltaChanges(delta, entityType);
                
                // 更新本地Delta Token
                updateLocalDeltaToken(entityType, extractDeltaToken(deltaJson));
                
            } catch (Exception e) {
                // 处理同步冲突
                handleSyncConflict(deltaJson, entityType, e);
            }
        }
        
        /**
         * 双向同步冲突检测
         */
        public ConflictResolution detectAndResolveConflicts(
                Delta localDelta, Delta remoteDelta, String entityType) {
            
            ConflictResolution resolution = new ConflictResolution();
            
            // 检测实体级冲突
            for (Entity localEntity : localDelta.getEntities()) {
                String entityId = getEntityId(localEntity);
                
                Optional<Entity> remoteEntity = remoteDelta.getEntities().stream()
                    .filter(e -> entityId.equals(getEntityId(e)))
                    .findFirst();
                
                if (remoteEntity.isPresent()) {
                    // 检测属性级冲突
                    EntityConflict conflict = detectPropertyConflicts(
                        localEntity, remoteEntity.get());
                    if (conflict.hasConflicts()) {
                        resolution.addConflict(conflict);
                    }
                }
            }
            
            // 检测删除冲突
            detectDeleteConflicts(localDelta, remoteDelta, resolution);
            
            // 检测链接冲突
            detectLinkConflicts(localDelta, remoteDelta, resolution);
            
            return resolution;
        }
        
        /**
         * 智能合并Delta变更
         */
        public Delta mergeDeltas(List<Delta> deltas, MergeStrategy strategy) {
            Delta mergedDelta = new Delta();
            
            Map<String, Entity> entityMap = new HashMap<>();
            Set<String> deletedEntityIds = new HashSet<>();
            Map<String, DeltaLink> addedLinksMap = new HashMap<>();
            Map<String, DeltaLink> deletedLinksMap = new HashMap<>();
            
            for (Delta delta : deltas) {
                // 合并实体变更
                for (Entity entity : delta.getEntities()) {
                    String entityId = getEntityId(entity);
                    if (!deletedEntityIds.contains(entityId)) {
                        Entity existing = entityMap.get(entityId);
                        if (existing == null) {
                            entityMap.put(entityId, entity);
                        } else {
                            // 按策略合并属性
                            Entity merged = mergeEntities(existing, entity, strategy);
                            entityMap.put(entityId, merged);
                        }
                    }
                }
                
                // 合并删除实体
                for (DeletedEntity deleted : delta.getDeletedEntities()) {
                    deletedEntityIds.add(deleted.getId());
                    entityMap.remove(deleted.getId());
                }
                
                // 合并链接操作
                mergeLinks(delta.getAddedLinks(), addedLinksMap, deletedLinksMap, true);
                mergeLinks(delta.getDeletedLinks(), deletedLinksMap, addedLinksMap, false);
            }
            
            // 构建最终Delta
            mergedDelta.getEntities().addAll(entityMap.values());
            
            for (String deletedId : deletedEntityIds) {
                mergedDelta.getDeletedEntities().add(
                    new DeletedEntity(deletedId, DeletedEntity.Reason.DELETED));
            }
            
            mergedDelta.getAddedLinks().addAll(addedLinksMap.values());
            mergedDelta.getDeletedLinks().addAll(deletedLinksMap.values());
            
            return mergedDelta;
        }
    }
}

3. 移动端离线同步

针对移动应用的离线数据同步场景。

移动端同步完整流程图

移动端数据分批处理流程图

离线冲突解决策略图

---