扩展ABP的Webhook功能，推送数据到第三方接口（企业微信群、钉钉群等）

前言

在上一篇文章【基于ASP.NET ZERO，开发SaaS版供应链管理系统】中有提到对Webhook功能的扩展改造，本文详细介绍一下具体过程。

Webhook功能操作说明，请参见此文档链接：Webhook数据推送

Webhook功能发布日期：

• ASP.NET Boilerplate（以下简称ABP）在v5.2（2020-02-18）版本中发布了Webhook功能，详细说明，请参见：官方帮助链接；
• ASP.NET ZERO（以下简称ZERO）在v8.2.0（2020-02-20）版本中发布了Webhook功能；
• 我们系统是在2021年4月完成了对Webhook功能的改造：内部接口（用户自行设定接口地址的）、第三方接口（微信内部群、钉钉群、聚水潭API等）。

1、Webhook定义

• 为了区分内部接口与第三方接口，在第三方接口名称前统一附加特定前缀，如：Third.WX.XXX、Third.DD.XXX等；
• 添加定义条目时候设定对应的特性（featureDependency），基于特性功能对不同租户显示或者隐藏定义的条目。

    public class AppWebhookDefinitionProvider : WebhookDefinitionProvider
    {
        public override void SetWebhooks(IWebhookDefinitionContext context)
        {
            //物料档案 - 全部可见
            context.Manager.Add(new WebhookDefinition(name: AppWebHookNames.T11071001_Created));
            context.Manager.Add(new WebhookDefinition(name: AppWebHookNames.T11071001_Updated));
            context.Manager.Add(new WebhookDefinition(name: AppWebHookNames.T11071001_Deleted));

            //生产订单 - 生产管理可见
            var featureC = new SimpleFeatureDependency("SCM.C");
            context.Manager.Add(new WebhookDefinition(name: AppWebHookNames.T13041001_Created, featureDependency: featureC));
            context.Manager.Add(new WebhookDefinition(name: AppWebHookNames.T13041001_Updated, featureDependency: featureC));
            context.Manager.Add(new WebhookDefinition(name: AppWebHookNames.T13041001_Deleted, featureDependency: featureC));
            context.Manager.Add(new WebhookDefinition(name: AppWebHookNames.T13041001_MRP_Data, featureDependency: featureC));

            //...
        }
    }

• 在CoreModule中添加Webhook定义，并设定参数选项：

    public class SCMCoreModule : AbpModule
    {
        public override void PreInitialize()
        {
            Configuration.Webhooks.Providers.Add<AppWebhookDefinitionProvider>();
            Configuration.Webhooks.TimeoutDuration = TimeSpan.FromMinutes(1);
            Configuration.Webhooks.IsAutomaticSubscriptionDeactivationEnabled = true;
            Configuration.Webhooks.MaxSendAttemptCount = 3;
            Configuration.Webhooks.MaxConsecutiveFailCountBeforeDeactivateSubscription = 10;

            //...
        }

        //...
    }

2、Webhook订阅

• 前端用户创建Webhook订阅记录（WebhookUri、Webhooks、Headers等），之后传递到后端API；
• 后端API通过WebhookSubscriptionManager添加保存WebhookSubscription（Webhook订阅）：

    [AbpAuthorize(AppPermissions.Pages_Administration_WebhookSubscription)]
    public class WebhookSubscriptionAppService : SCMAppServiceBase, IWebhookSubscriptionAppService
    {
        //...

        [AbpAuthorize(AppPermissions.Pages_Administration_WebhookSubscription_Create)]
        public async Task AddSubscription(WebhookSubscription subscription)
        {
            subscription.TenantId = AbpSession.TenantId;

            await _webHookSubscriptionManager.AddOrUpdateSubscriptionAsync(subscription);
        }

        //...
    }

3、Webhook发布（数据推送）

监测实体事件（CreatedEvent、UpdatedEvent、DeletedEvent）数据，按租户用户创建的Webhook订阅，推送数据：

    public class T11071001Syncronizer :
        IEventHandler<EntityCreatedEventData<T11071001>>,
        IEventHandler<EntityUpdatedEventData<T11071001>>,
        IEventHandler<EntityDeletedEventData<T11071001>>,
        ITransientDependency
    {
        private readonly IAppWebhookPublisher _appWebhookPublisher;

        public T11071001Syncronizer(IAppWebhookPublisher appWebhookPublisher)
        {
            _appWebhookPublisher = appWebhookPublisher;
        }
        public void HandleEvent(EntityCreatedEventData<T11071001> eventData)
        {
            DoWebhook("N", eventData.Entity);
        }

        public void HandleEvent(EntityUpdatedEventData<T11071001> eventData)
        {
            DoWebhook("U", eventData.Entity);
        }

        public void HandleEvent(EntityDeletedEventData<T11071001> eventData)
        {
            int? tenantId = eventData.Entity.TenantId;
            string whName = AppWebHookNames.T11071001_Deleted;
            var subscriptions = _appWebhookPublisher.GetSubscriptions(tenantId, whName);
            if (subscriptions == null) { return; }

            _appWebhookPublisher.PublishWebhookUOW(whName, eventData.Entity, tenantId, subscriptions);
        }

    }

• DoWebhook()方法：基于具体的订阅（内部接口、第三方接口等）推送对应的内容：

        private void DoWebhook(string nu, T11071001 entity)
        {
            int? tenantId = entity.TenantId;
            var whCache = _appWebhookPublisher.GetWebhookCache(tenantId); if (whCache.Count == 0) { return; }

            string whName = nu == "N" ? AppWebHookNames.T11071001_Created : AppWebHookNames.T11071001_Updated;
            string whNameWX = AppWebHookNames.WX_T11071001_Created;
            string whNameDD = AppWebHookNames.DD_T11071001_Created;

            bool isWH = whCache.Names.ContainsKey(whName);
            bool isWX = whCache.Names.ContainsKey(whNameWX);
            bool isDD = whCache.Names.ContainsKey(whNameDD);

            if (!(isWH || isWX || isDD)) { return; }

            var data = ObjectMapper.Map<T11071001WebhookDto>(entity);

            //内部接口
            if (isWH)
            {
                _appWebhookPublisher.PublishWebhookUOW(whName, data, tenantId, whCache.Names[whName], false);
            }

            //企业微信内部群
            if (isWX)
            {
                var wxData = new WxTCardWebhookDto { template_card = GetWxTCard(data, tenantId, nu) };
                _appWebhookPublisher.PublishWebhookUOW(whNameWX, wxData, tenantId, whCache.Names[whNameWX], true);
            }

            //钉钉内部群
            if (isDD)
            {
                var title = GetNUTitle(nu, L(T));
                var mdText = GetNewMarkdown(data, title);
                var ddData = new DdMarkdownWebhookDto { markdown = new DdMarkdownContentDto { title = title, text = mdText } };
                _appWebhookPublisher.PublishWebhookUOW(whNameDD, ddData, tenantId, whCache.Names[whNameDD], true);
            }
        }

• GetWebhookCache()方法：实现按租户缓存Webhook订阅的数据：

        public SCMWebhookCacheItem GetWebhookCache(int? tenantId)
        {
           return SetAndGetCache(tenantId);
        }

        private SCMWebhookCacheItem SetAndGetCache(int? tenantId, string keyName = "SubscriptionCount")
        {
           int tid = tenantId ?? 0; var cacheKey = $"{keyName}-{tid}";

           return _cacheManager.GetSCMWebhookCache().Get(cacheKey, () =>
           {
                int count = 0;
                var names = new Dictionary<string, List<WebhookSubscription>>();

                UnitOfWorkManager.WithUnitOfWork(() =>
                {
                    using (UnitOfWorkManager.Current.SetTenantId(tenantId))
                    {
                        if (_featureChecker.IsEnabled(tid, "SCM.H")) //Feature核查
                        {
                            var items = _webhookSubscriptionRepository.GetAllList(e => e.TenantId == tenantId && e.IsActive == true);
                            count = items.Count;

                            foreach (var item in items)
                            {
                                if (string.IsNullOrWhiteSpace(item.Webhooks)) { continue; }
                                var whNames = JsonHelper.DeserializeObject<string[]>(item.Webhooks); if (whNames == null) { continue; }
                                foreach (string whName in whNames)
                                {
                                    if (names.ContainsKey(whName))
                                    {
                                        names[whName].Add(item.ToWebhookSubscription());
                                    }
                                    else
                                    {
                                        names.Add(whName, new List<WebhookSubscription> { item.ToWebhookSubscription() });
                                    }
                                }
                            }
                        }
                    }
                });

                return new SCMWebhookCacheItem(count, names);
            });
        }

• PublishWebhookUOW()方法：替换ABP中WebHookPublisher的默认实现，直接按传入的订阅，通过WebhookSenderJob推送数据：

        public void PublishWebhookUOW(string webHookName, object data, int? tenantId, List<WebhookSubscription> webhookSubscriptions = null, bool sendExactSameData = false)
        {
            UnitOfWorkManager.WithUnitOfWork(() =>
            {
                using (UnitOfWorkManager.Current.SetTenantId(tenantId))
                {
                    Publish(webHookName, data, tenantId, webhookSubscriptions, sendExactSameData);
                }
            });
        }

        private void Publish(string webhookName, object data, int? tenantId, List<WebhookSubscription> webhookSubscriptions, bool sendExactSameData = false)
        {
            if (string.IsNullOrWhiteSpace(webhookName)) { return; }

            //若无直接传入订阅则按webhookName查询
            webhookSubscriptions ??= _webhookSubscriptionRepository.GetAllList(subscriptionInfo =>
                    subscriptionInfo.TenantId == tenantId &&
                    subscriptionInfo.IsActive &&
                    subscriptionInfo.Webhooks.Contains("\"" + webhookName + "\"")
                ).Select(subscriptionInfo => subscriptionInfo.ToWebhookSubscription()).ToList();

            if (webhookSubscriptions.IsNullOrEmpty()) { return; }

            var webhookInfo = SaveAndGetWebhookEvent(tenantId, webhookName, data);

            foreach (var webhookSubscription in webhookSubscriptions)
            {
                var jobArgs = new WebhookSenderArgs
                {
                    TenantId = webhookSubscription.TenantId,
                    WebhookEventId = webhookInfo.Id,
                    Data = webhookInfo.Data,
                    WebhookName = webhookInfo.WebhookName,
                    WebhookSubscriptionId = webhookSubscription.Id,
                    Headers = webhookSubscription.Headers,
                    Secret = webhookSubscription.Secret,
                    WebhookUri = webhookSubscription.WebhookUri,
                    SendExactSameData = sendExactSameData
                };

                //指定队列执行任务，由触发事件的server执行
                IBackgroundJobClient hangFireClient = new BackgroundJobClient();
                hangFireClient.Create<WebhookSenderJob>(x => x.ExecuteAsync(jobArgs), new EnqueuedState(AppVersionHelper.MachineName));
            }
        }

• WebhookSenderJob：重写WebhookManager的SignWebhookRequest方法，对于第三方接口，不添加签名的Header：

        public override void SignWebhookRequest(HttpRequestMessage request, string serializedBody, string secret)
        {
            if (request == null)
            {
                throw new ArgumentNullException(nameof(request));
            }

            //第三方接口，不添加签名Header
            if (IsThirdAPI(request))
            {
                return;
            }

            if (string.IsNullOrWhiteSpace(serializedBody))
            {
                throw new ArgumentNullException(nameof(serializedBody));
            }

            var secretBytes = Encoding.UTF8.GetBytes(secret);

            using (var hasher = new HMACSHA256(secretBytes))
            {
                request.Content = new StringContent(serializedBody, Encoding.UTF8, "application/json");

                var data = Encoding.UTF8.GetBytes(serializedBody);
                var sha256 = hasher.ComputeHash(data);

                var headerValue = string.Format(CultureInfo.InvariantCulture, SignatureHeaderValueTemplate, BitConverter.ToString(sha256));

                request.Headers.Add(SignatureHeaderName, headerValue);
            }
        }

• WebhookSenderJob：重写WebhookSender的CreateWebhookRequestMessage方法，对于第三方接口，进行特殊处理：

        protected override HttpRequestMessage CreateWebhookRequestMessage(WebhookSenderArgs webhookSenderArgs)
        {
            return webhookSenderArgs.WebhookName switch
            {
                AppWebHookNames.JST_supplier_upload => JSTHttpRequestMessage(webhookSenderArgs), //聚水潭 - 供应商上传
                //...
                _ => new HttpRequestMessage(HttpMethod.Post, webhookSenderArgs.WebhookUri)
            };
        }

• WebhookSenderJob：重写WebhookSender的AddAdditionalHeaders方法, 对于第三方接口，不添加Headers：

        protected override void AddAdditionalHeaders(HttpRequestMessage request, WebhookSenderArgs webhookSenderArgs)
        {
            //第三方接口，不添加Header
            if (IsThirdAPI(request))
            {
                return;
            }

            foreach (var header in webhookSenderArgs.Headers)
            {
                if (request.Headers.TryAddWithoutValidation(header.Key, header.Value))
                {
                    continue;
                }

                if (request.Content.Headers.TryAddWithoutValidation(header.Key, header.Value))
                {
                    continue;
                }

                throw new Exception($"Invalid Header. SubscriptionId:{webhookSenderArgs.WebhookSubscriptionId},Header: {header.Key}:{header.Value}");
            }
        }

• WebhookSenderJob：重写WebhookSender的SendHttpRequest方法，处理第三方接口的回传数据：

        protected override async Task<(bool isSucceed, HttpStatusCode statusCode, string content)> SendHttpRequest(HttpRequestMessage request)
        {
            using var client = _httpClientFactory.CreateClient(); //避免使用 new HttpClient()方式
            client.Timeout = _webhooksConfiguration.TimeoutDuration;

            var response = await client.SendAsync(request);

            var isSucceed = response.IsSuccessStatusCode;
            var statusCode = response.StatusCode;
            var content = await response.Content.ReadAsStringAsync();

            //第三方接口，需要处理回传的数据
            if (IsThirdAPI(request))
            {
                string method = TryGetHeader(request.Headers, "ThirdAPI1");
                int tenantId = Convert.ToInt32(TryGetHeader(request.Headers, "ThirdAPI2"));
                switch (method)
                {
                    case AppWebHookNames.JST_supplier_upload: await JSTSupplierUploadResponse(method, content, tenantId); break;
                    //...
                    default: break;
                }
            }

            return (isSucceed, statusCode, content);
        }

总结

基于ABP/ZERO的Webhook功能实现，进行一些扩展改造，可以实现业务数据按用户订阅进行推送，包括推送到第三方接口（企业微信群、钉钉等），在很大程度上提升了业务系统的灵活性与实用性。