這篇文章，我們將從Ocelot的中間件源碼分析，目前Ocelot已經實現那些功能，還有那些功能在我們實際項目中暫時還未實現，如果我們要使用這些功能，應該如何改造等方面來說明。

一、Ocelot源碼解讀

在使用一個組件前，最好我們要了解其中的一些原理，否則在使用過程中遇到問題，也無從下手，今天我帶著大家一起來解讀下Ocelot源碼，并梳理出具體實現的原理和流程，便于我們根據需求擴展應用。
Ocelot源碼地址[https://github.com/ThreeMammals/Ocelot],
Ocelot文檔地址[https://ocelot.readthedocs.io/en/latest/]

查看.NETCORE相關中間件源碼，我們優先找到入口方法，比如Ocelot中間件使用的是app.UseOcelot(),我們直接搜索UserOcelot,我們會找到OcelotMiddlewareExtensions方法，里面是Ocelot中間件實際運行的方式和流程。

然后繼續順藤摸瓜，查看詳細的實現，我們會發現如下代碼

public static async Task<IApplicationBuilder> UseOcelot(this IApplicationBuilder builder, OcelotPipelineConfiguration pipelineConfiguration) ? ? ? ?{ ? //創建配置信息var configuration = await CreateConfiguration(builder); ? ? ? ? ? ?//監聽配置信息ConfigureDiagnosticListener(builder); ? ? ? ? ? ?//創建執行管道return CreateOcelotPipeline(builder, pipelineConfiguration);}

然后我們繼續跟蹤到創建管道方法，可以發現Ocelot的執行流程已經被找到，現在問題變的簡單了，直接查看

private static IApplicationBuilder CreateOcelotPipeline(IApplicationBuilder builder, OcelotPipelineConfiguration pipelineConfiguration){ ? ?var pipelineBuilder = new OcelotPipelineBuilder(builder.ApplicationServices); ? ?//詳細創建的管道順序在此方法pipelineBuilder.BuildOcelotPipeline(pipelineConfiguration); ? ?var firstDelegate = pipelineBuilder.Build(); ? ?/*inject first delegate into first piece of asp.net middleware..maybe not like thisthen because we are updating the http context in ocelot it comes out correct forrest of asp.net..*/builder.Properties["analysis.NextMiddlewareName"] = "TransitionToOcelotMiddleware";builder.Use(async (context, task) =>{ ? ? ? ? ? ? ? ? ? ?var downstreamContext = new DownstreamContext(context); ? ? ? ? ? ? ? ? ? ?await firstDelegate.Invoke(downstreamContext);}); ? ?return builder; }

管道創建流程及實現，會不會感覺到摸到大動脈了，核心的功能及原理基本找到了，那以后動手術也就可以避開一些坑了，我們可以對著這個執行順序，再查看詳細的源碼，按照這個執行順序查看源碼，您就會發現整個思路非常清晰，每一步的實現一目了然。為了更直觀的介紹源碼的解讀方式，這里我們就拿我們后續要操刀的中間件來講解下中間件的具體實現。

public static class OcelotPipelineExtensions{ ? ? ? ?public static OcelotRequestDelegate BuildOcelotPipeline(this IOcelotPipelineBuilder builder,OcelotPipelineConfiguration pipelineConfiguration){ ? ? ? ? ? ?// This is registered to catch any global exceptions that are not handled// It also sets the Request Id if anything is set globallybuilder.UseExceptionHandlerMiddleware(); ? ? ? ? ? ?// If the request is for websockets upgrade we fork into a different pipelinebuilder.MapWhen(context => context.HttpContext.WebSockets.IsWebSocketRequest,app =>{ ? ? ? ? ? ? ? ? ? ?app.UseDownstreamRouteFinderMiddleware(); ? ? ? ? ? ? ? ? ? ?app.UseDownstreamRequestInitialiser(); ? ? ? ? ? ? ? ? ? ?app.UseLoadBalancingMiddleware(); ? ? ? ? ? ? ? ? ? ?app.UseDownstreamUrlCreatorMiddleware(); ? ? ? ? ? ? ? ? ? ?app.UseWebSocketsProxyMiddleware();}); ? ? ? ? ? ?// Allow the user to respond with absolutely anything they want.builder.UseIfNotNull(pipelineConfiguration.PreErrorResponderMiddleware); ? ? ? ? ? ?// This is registered first so it can catch any errors and issue an appropriate responsebuilder.UseResponderMiddleware(); ? ? ? ? ? ?// Then we get the downstream route informationbuilder.UseDownstreamRouteFinderMiddleware(); ? ? ? ? ? ?// This security module, IP whitelist blacklist, extended security mechanismbuilder.UseSecurityMiddleware(); ? ? ? ? ? ?//Expand other branch pipesif (pipelineConfiguration.MapWhenOcelotPipeline != null){ ? ? ? ? ? ? ? ?foreach (var pipeline in pipelineConfiguration.MapWhenOcelotPipeline){ ? ? ? ? ? ? ? ? ? ?builder.MapWhen(pipeline);}} ? ? ? ? ? ?// Now we have the ds route we can transform headers and stuff?builder.UseHttpHeadersTransformationMiddleware(); ? ? ? ? ? ?// Initialises downstream requestbuilder.UseDownstreamRequestInitialiser(); ? ? ? ? ? ?// We check whether the request is ratelimit, and if there is no continue processingbuilder.UseRateLimiting(); ? ? ? ? ? ?// This adds or updates the request id (initally we try and set this based on global config in the error handling middleware)// If anything was set at global level and we have a different setting at re route level the global stuff will be overwritten// This means you can get a scenario where you have a different request id from the first piece of middleware to the request id middleware.builder.UseRequestIdMiddleware(); ? ? ? ? ? ?// Allow pre authentication logic. The idea being people might want to run something custom before what is built in.builder.UseIfNotNull(pipelineConfiguration.PreAuthenticationMiddleware); ? ? ? ? ? ?// Now we know where the client is going to go we can authenticate them.// We allow the ocelot middleware to be overriden by whatever the// user wantsif (pipelineConfiguration.AuthenticationMiddleware == null){ ? ? ? ? ? ? ? ?builder.UseAuthenticationMiddleware();} ? ? ? ? ? ?else{ ? ? ? ? ? ? ? ?builder.Use(pipelineConfiguration.AuthenticationMiddleware);} ? ? ? ? ? ?// The next thing we do is look at any claims transforms in case this is important for authorisationbuilder.UseClaimsToClaimsMiddleware(); ? ? ? ? ? ?// Allow pre authorisation logic. The idea being people might want to run something custom before what is built in.builder.UseIfNotNull(pipelineConfiguration.PreAuthorisationMiddleware); ? ? ? ? ? ?// Now we have authenticated and done any claims transformation we // can authorise the request// We allow the ocelot middleware to be overriden by whatever the// user wantsif (pipelineConfiguration.AuthorisationMiddleware == null){//使用自定義認證，移除默認的認證方式//builder.UseAuthorisationMiddleware();}else{ ? ? ? ? ? ? ? ?builder.Use(pipelineConfiguration.AuthorisationMiddleware);} ? ? ? ? ? ?// Now we can run the claims to headers transformation middlewarebuilder.UseClaimsToHeadersMiddleware(); ? ? ? ? ? ?// Allow the user to implement their own query string manipulation logicbuilder.UseIfNotNull(pipelineConfiguration.PreQueryStringBuilderMiddleware); ? ? ? ? ? ?// Now we can run any claims to query string transformation middlewarebuilder.UseClaimsToQueryStringMiddleware(); ? ? ? ? ? ?// Get the load balancer for this requestbuilder.UseLoadBalancingMiddleware(); ? ? ? ? ? ?// This takes the downstream route we retrieved earlier and replaces any placeholders with the variables that should be usedbuilder.UseDownstreamUrlCreatorMiddleware(); ? ? ? ? ? ?// Not sure if this is the best place for this but we use the downstream url // as the basis for our cache key.builder.UseOutputCacheMiddleware(); ? ? ? ? ? ?//We fire off the request and set the response on the scoped data repobuilder.UseHttpRequesterMiddleware(); ? ? ? ? ? ?return builder.Build();} ? ?private static void UseIfNotNull(this IOcelotPipelineBuilder builder,Func<DownstreamContext, Func<Task>, Task> middleware){ ? ? ? ? ? ?if (middleware != null){ ? ? ? ? ? ? ? ?builder.Use(middleware);}}}

限流中間件實現解析

實現代碼如下builder.UseRateLimiting();，我們轉到定義，得到如下代碼，詳細的實現邏輯在ClientRateLimitMiddleware方法里，繼續轉定義到這個方法，我把方法里用到的內容注釋了下。

public static class RateLimitMiddlewareExtensions{ ? ?public static IOcelotPipelineBuilder UseRateLimiting(this IOcelotPipelineBuilder builder) ? ?{ ? ? ? ?return builder.UseMiddleware<ClientRateLimitMiddleware>();} }public class ClientRateLimitMiddleware : OcelotMiddleware{ ? ? ? ?private readonly OcelotRequestDelegate _next; ? ? ? ?private readonly IRateLimitCounterHandler _counterHandler; ? ? ? ?private readonly ClientRateLimitProcessor _processor; ? ? ? ?public ClientRateLimitMiddleware(OcelotRequestDelegate next,IOcelotLoggerFactory loggerFactory,IRateLimitCounterHandler counterHandler):base(loggerFactory.CreateLogger<ClientRateLimitMiddleware>()) ? ? ? ?{_next = next;_counterHandler = counterHandler;_processor = new ClientRateLimitProcessor(counterHandler);} ? ? ? ?//熟悉的Tnvoke方法，所有的邏輯都在此方法里。public async Task Invoke(DownstreamContext context) ? ? ? ?{ ? ? ? ? ? ?var options = context.DownstreamReRoute.RateLimitOptions; ? ? ? ? ? ?// 校驗是否啟用限流配置if (!context.DownstreamReRoute.EnableEndpointEndpointRateLimiting){//未啟用直接進入下一個中間件Logger.LogInformation($"EndpointRateLimiting is not enabled for {context.DownstreamReRoute.DownstreamPathTemplate.Value}"); ? ? ? ? ? ? ? ?await _next.Invoke(context); ? ? ? ? ? ? ? ?return;} ? ? ? ? ? ?// 獲取配置的校驗客戶端的方式var identity = SetIdentity(context.HttpContext, options); ? ? ? ? ? ?// 校驗是否為白名單if (IsWhitelisted(identity, options)){//白名單直接放行Logger.LogInformation($"{context.DownstreamReRoute.DownstreamPathTemplate.Value} is white listed from rate limiting"); ? ? ? ? ? ? ? ?await _next.Invoke(context); ? ? ? ? ? ? ? ?return;} ? ? ? ? ? ?var rule = options.RateLimitRule; ? ? ? ? ? ?if (rule.Limit > 0){//限流數是否大于0// 獲取當前客戶端請求情況，這里需要注意_processor是從哪里注入的，后續重var counter = _processor.ProcessRequest(identity, options); ? ? ? ? ? ? ? ?// 校驗請求數是否大于限流數if (counter.TotalRequests > rule.Limit){ ? ? ? ? ? ? ? ? ? ?//獲取下次有效請求的時間，就是避免每次請求，都校驗一次var retryAfter = _processor.RetryAfterFrom(counter.Timestamp, rule); ? ? ? ? ? ? ? ? ? ?// 寫入日志LogBlockedRequest(context.HttpContext, identity, counter, rule, context.DownstreamReRoute); ? ? ? ? ? ? ? ? ? ?var retrystring = retryAfter.ToString(System.Globalization.CultureInfo.InvariantCulture); ? ? ? ? ? ? ? ? ? ?// 拋出超出限流異常并把下次可請求時間寫入header里。await ReturnQuotaExceededResponse(context.HttpContext, options, retrystring); ? ? ? ? ? ? ? ? ? ?return;}} ? ? ? ? ? ?//如果啟用了限流頭部if (!options.DisableRateLimitHeaders){ ? ? ? ? ? ? ? ?var headers = _processor.GetRateLimitHeaders(context.HttpContext, identity, options);context.HttpContext.Response.OnStarting(SetRateLimitHeaders, state: headers);} ? ? ? ? ? ?//進入下一個中間件await _next.Invoke(context);} ? ? ? ?public virtual ClientRequestIdentity SetIdentity(HttpContext httpContext, RateLimitOptions option) ? ? ? ?{ ? ? ? ? ? ?var clientId = "client"; ? ? ? ? ? ?if (httpContext.Request.Headers.Keys.Contains(option.ClientIdHeader)){clientId = httpContext.Request.Headers[option.ClientIdHeader].First();} ? ? ? ? ? ?return new ClientRequestIdentity(clientId,httpContext.Request.Path.ToString().ToLowerInvariant(),httpContext.Request.Method.ToLowerInvariant());} ? ? ? ?public bool IsWhitelisted(ClientRequestIdentity requestIdentity, RateLimitOptions option) ? ? ? ?{ ? ? ? ? ? ?if (option.ClientWhitelist.Contains(requestIdentity.ClientId)){ ? ? ? ? ? ? ? ?return true;} ? ? ? ? ? ?return false;} ? ? ? ?public virtual void LogBlockedRequest(HttpContext httpContext, ClientRequestIdentity identity, RateLimitCounter counter, RateLimitRule rule, DownstreamReRoute downstreamReRoute) ? ? ? ?{Logger.LogInformation( ? ? ? ? ? ? ? ?$"Request {identity.HttpVerb}:{identity.Path} from ClientId {identity.ClientId} has been blocked, quota {rule.Limit}/{rule.Period} exceeded by {counter.TotalRequests}. Blocked by rule { downstreamReRoute.UpstreamPathTemplate.OriginalValue }, TraceIdentifier {httpContext.TraceIdentifier}.");} ? ? ? ?public virtual Task ReturnQuotaExceededResponse(HttpContext httpContext, RateLimitOptions option, string retryAfter) ? ? ? ?{ ? ? ? ? ? ?var message = string.IsNullOrEmpty(option.QuotaExceededMessage) ? $"API calls quota exceeded! maximum admitted {option.RateLimitRule.Limit} per {option.RateLimitRule.Period}." : option.QuotaExceededMessage; ? ? ? ? ? ?if (!option.DisableRateLimitHeaders){httpContext.Response.Headers["Retry-After"] = retryAfter;}httpContext.Response.StatusCode = option.HttpStatusCode; ? ? ? ? ? ?return httpContext.Response.WriteAsync(message);} ? ? ? ?private Task SetRateLimitHeaders(object rateLimitHeaders) ? ? ? ?{ ? ? ? ? ? ?var headers = (RateLimitHeaders)rateLimitHeaders;headers.Context.Response.Headers["X-Rate-Limit-Limit"] = headers.Limit;headers.Context.Response.Headers["X-Rate-Limit-Remaining"] = headers.Remaining;headers.Context.Response.Headers["X-Rate-Limit-Reset"] = headers.Reset; ? ? ? ? ? ?return Task.CompletedTask;}}

通過源碼解析，發現實現一個限流還是很簡單的嗎！再進一步解析，IRateLimitCounterHandler?ClientRateLimitProcessor里的相關接口又是怎么實現的呢？這時候我們就需要了解下.NETCORE 的運行原理，其中ConfigureServices方法實現了依賴注入(DI)的配置。這時候我們看下Ocelot是在哪里進行注入的呢？

services.AddOcelot()是不是印象深刻呢？原來所有的注入信息都寫在這里，那么問題簡單了，Ctrl+F查找AddOcelot方法，馬上就能定位到ServiceCollectionExtensions方法，然后再轉到定義OcelotBuilder

public static class ServiceCollectionExtensions{ ? ?public static IOcelotBuilder AddOcelot(this IServiceCollection services) ? ?{ ? ? ? ?var service = services.First(x => x.ServiceType == typeof(IConfiguration)); ? ? ? ?var configuration = (IConfiguration)service.ImplementationInstance; ? ? ? ?return new OcelotBuilder(services, configuration);} ? ?public static IOcelotBuilder AddOcelot(this IServiceCollection services, IConfiguration configuration) ? ?{ ? ? ? ?return new OcelotBuilder(services, configuration);} }

又摸到大動脈啦，現在問題迎刃而解，原來所有的注入都寫在這里，從這里可以找下我們熟悉的幾個接口注入。

public OcelotBuilder(IServiceCollection services, IConfiguration configurationRoot) {Configuration = configurationRoot;Services = services;Services.Configure<FileConfiguration>(configurationRoot);Services.TryAddSingleton<IOcelotCache<FileConfiguration>, InMemoryCache<FileConfiguration>>();Services.TryAddSingleton<IOcelotCache<CachedResponse>, InMemoryCache<CachedResponse>>();Services.TryAddSingleton<IHttpResponseHeaderReplacer, HttpResponseHeaderReplacer>();Services.TryAddSingleton<IHttpContextRequestHeaderReplacer, HttpContextRequestHeaderReplacer>();Services.TryAddSingleton<IHeaderFindAndReplaceCreator, HeaderFindAndReplaceCreator>();Services.TryAddSingleton<IInternalConfigurationCreator, FileInternalConfigurationCreator>();Services.TryAddSingleton<IInternalConfigurationRepository, InMemoryInternalConfigurationRepository>();Services.TryAddSingleton<IConfigurationValidator, FileConfigurationFluentValidator>();Services.TryAddSingleton<HostAndPortValidator>();Services.TryAddSingleton<IReRoutesCreator, ReRoutesCreator>();Services.TryAddSingleton<IAggregatesCreator, AggregatesCreator>();Services.TryAddSingleton<IReRouteKeyCreator, ReRouteKeyCreator>();Services.TryAddSingleton<IConfigurationCreator, ConfigurationCreator>();Services.TryAddSingleton<IDynamicsCreator, DynamicsCreator>();Services.TryAddSingleton<ILoadBalancerOptionsCreator, LoadBalancerOptionsCreator>();Services.TryAddSingleton<ReRouteFluentValidator>();Services.TryAddSingleton<FileGlobalConfigurationFluentValidator>();Services.TryAddSingleton<FileQoSOptionsFluentValidator>();Services.TryAddSingleton<IClaimsToThingCreator, ClaimsToThingCreator>();Services.TryAddSingleton<IAuthenticationOptionsCreator, AuthenticationOptionsCreator>();Services.TryAddSingleton<IUpstreamTemplatePatternCreator, UpstreamTemplatePatternCreator>();Services.TryAddSingleton<IRequestIdKeyCreator, RequestIdKeyCreator>();Services.TryAddSingleton<IServiceProviderConfigurationCreator,ServiceProviderConfigurationCreator>();Services.TryAddSingleton<IQoSOptionsCreator, QoSOptionsCreator>();Services.TryAddSingleton<IReRouteOptionsCreator, ReRouteOptionsCreator>();Services.TryAddSingleton<IRateLimitOptionsCreator, RateLimitOptionsCreator>();Services.TryAddSingleton<IBaseUrlFinder, BaseUrlFinder>();Services.TryAddSingleton<IRegionCreator, RegionCreator>();Services.TryAddSingleton<IFileConfigurationRepository, DiskFileConfigurationRepository>();Services.TryAddSingleton<IFileConfigurationSetter, FileAndInternalConfigurationSetter>();Services.TryAddSingleton<IServiceDiscoveryProviderFactory, ServiceDiscoveryProviderFactory>();Services.TryAddSingleton<ILoadBalancerFactory, LoadBalancerFactory>();Services.TryAddSingleton<ILoadBalancerHouse, LoadBalancerHouse>();Services.TryAddSingleton<IOcelotLoggerFactory, AspDotNetLoggerFactory>();Services.TryAddSingleton<IRemoveOutputHeaders, RemoveOutputHeaders>();Services.TryAddSingleton<IClaimToThingConfigurationParser, ClaimToThingConfigurationParser>();Services.TryAddSingleton<IClaimsAuthoriser, ClaimsAuthoriser>();Services.TryAddSingleton<IScopesAuthoriser, ScopesAuthoriser>();Services.TryAddSingleton<IAddClaimsToRequest, AddClaimsToRequest>();Services.TryAddSingleton<IAddHeadersToRequest, AddHeadersToRequest>();Services.TryAddSingleton<IAddQueriesToRequest, AddQueriesToRequest>();Services.TryAddSingleton<IClaimsParser, ClaimsParser>();Services.TryAddSingleton<IUrlPathToUrlTemplateMatcher, RegExUrlMatcher>();Services.TryAddSingleton<IPlaceholderNameAndValueFinder, UrlPathPlaceholderNameAndValueFinder>();Services.TryAddSingleton<IDownstreamPathPlaceholderReplacer, DownstreamTemplatePathPlaceholderReplacer>();Services.TryAddSingleton<IDownstreamRouteProvider, DownstreamRouteFinder>();Services.TryAddSingleton<IDownstreamRouteProvider, DownstreamRouteCreator>();Services.TryAddSingleton<IDownstreamRouteProviderFactory, DownstreamRouteProviderFactory>();Services.TryAddSingleton<IHttpRequester, HttpClientHttpRequester>();Services.TryAddSingleton<IHttpResponder, HttpContextResponder>();Services.TryAddSingleton<IErrorsToHttpStatusCodeMapper, ErrorsToHttpStatusCodeMapper>();Services.TryAddSingleton<IRateLimitCounterHandler, MemoryCacheRateLimitCounterHandler>();Services.TryAddSingleton<IHttpClientCache, MemoryHttpClientCache>();Services.TryAddSingleton<IRequestMapper, RequestMapper>();Services.TryAddSingleton<IHttpHandlerOptionsCreator, HttpHandlerOptionsCreator>();Services.TryAddSingleton<IDownstreamAddressesCreator, DownstreamAddressesCreator>();Services.TryAddSingleton<IDelegatingHandlerHandlerFactory, DelegatingHandlerHandlerFactory>();Services.TryAddSingleton<IHttpRequester, HttpClientHttpRequester>();// see this for why we register this as singleton http://stackoverflow.com/questions/37371264/invalidoperationexception-unable-to-resolve-service-for-type-microsoft-aspnetc// could maybe use a scoped data repositoryServices.TryAddSingleton<IHttpContextAccessor, HttpContextAccessor>();Services.TryAddSingleton<IRequestScopedDataRepository, HttpDataRepository>();Services.AddMemoryCache();Services.TryAddSingleton<OcelotDiagnosticListener>();Services.TryAddSingleton<IMultiplexer, Multiplexer>();Services.TryAddSingleton<IResponseAggregator, SimpleJsonResponseAggregator>();Services.TryAddSingleton<ITracingHandlerFactory, TracingHandlerFactory>();Services.TryAddSingleton<IFileConfigurationPollerOptions, InMemoryFileConfigurationPollerOptions>();Services.TryAddSingleton<IAddHeadersToResponse, AddHeadersToResponse>();Services.TryAddSingleton<IPlaceholders, Placeholders>();Services.TryAddSingleton<IResponseAggregatorFactory, InMemoryResponseAggregatorFactory>();Services.TryAddSingleton<IDefinedAggregatorProvider, ServiceLocatorDefinedAggregatorProvider>();Services.TryAddSingleton<IDownstreamRequestCreator, DownstreamRequestCreator>();Services.TryAddSingleton<IFrameworkDescription, FrameworkDescription>();Services.TryAddSingleton<IQoSFactory, QoSFactory>();Services.TryAddSingleton<IExceptionToErrorMapper, HttpExeptionToErrorMapper>();//add security this.AddSecurity();//add asp.net services..var assembly = typeof(FileConfigurationController).GetTypeInfo().Assembly;Services.AddMvcCore().AddApplicationPart(assembly).AddControllersAsServices().AddAuthorization().AddJsonFormatters();Services.AddLogging();Services.AddMiddlewareAnalysis();Services.AddWebEncoders(); }

至此Ocelot源碼解析就到這里了，其他的具體實現代碼就根據流程一個一個查看即可，這里就不詳細講解了，因為我們已經掌握整個Ocelot代碼的運行原理和實現方式及流程，項目里其他的一大堆的代碼都是圍繞這個流程去一步一步實現的。

有沒有感覺添加一個中間件不是很復雜呢，是不是都躍躍欲試，準備嘗試開發自己的自定義中間件啦，本篇就不介紹中間件的具體開發流程了，后續實戰中會包含部分項目中需要用到的中間件，到時候會詳細講解如何規劃和開發一個滿足自己項目需求的中間件。

二、結合項目梳理功能

在完整學習完Ocelot文檔和源碼后，我們基本掌握了Ocelot目前已經實現的功能，再結合我們實際項目需求，我們梳理下還有哪些功能可能需要自己擴展實現。

項目設計網關基本需求包括路由、認證、授權、限流、緩存，仔細學習文檔和源碼后發現功能都已經存在，那是不是我們就可以直接拿來使用呢？這時候我們需要拿出一些復雜業務場景來對號入座，看能否實現復雜場景的一些應用。

1、授權

能否為每一個客戶端設置獨立的訪問權限，如果客戶端A可以訪問服務A、服務B，客戶端B只能訪問服務A，從網關層面直接授權，不滿足需求不路由到具體服務。從文檔和代碼分析后發現暫時未實現。

2、限流

能否為每一個客戶端設置不能限流規則，例如客戶端A為我們內容應用，我希望對服務A不啟用限流，客戶端B為第三方接入應用，我需要B訪問服務A訪問進行單獨限流（30次/分鐘），看能否通過配置實現自定義限流。從文檔和代碼分析后發現暫時未實現。

3、緩存

通過代碼發現目前緩存實現的只是Dictionary方式實現的緩存，不能實現分布式結構的應用。

通過分析我們發現列舉的5個基本需求，盡然有3個在我們實際項目應用中可能會存在問題，如果不解決這些問題，很難直接拿這個完美的網關項目應用到正式項目，所以我們到通過擴展Ocelot方法來實現我們的目的。

如何擴展呢

為了滿足我們項目應用的需要，我們需要為每一個路由進行單獨設置，如果還采用配置文件的方式，肯定無法滿足需求，且后續網關動態增加路由、授權、限流等無法控制，所以我們需要把網關配置信息從配置文件中移到數據庫中，由數據庫中的路由表、限流表、授權表等方式記錄當前網關的應用，且后續擴展直接在數據庫中增加或減少相關配置，然后動態更新網關配置實現網關的高可用。

想一想是不是有點小激動，原來只要稍微改造下寶駿瞬間變寶馬，那接下來的課程就是網關改造之旅，我會從設計、思想、編碼等方面講解下如何實現我們的第一輛寶馬。

本系列文章我也是邊想邊寫邊實現，如果發現中間有任何描述或實現不當的地方，也請各位大神批評指正，我會第一時間整理并修正，避免讓后續學習的人走彎路。

相關文章：

• AspNetCore中使用Ocelot之 IdentityServer4

• Ocelot-基于.NET Core的開源網關實現

• .NET Core微服務之基于Ocelot+IdentityServer實現統一驗證與授權

• Swagger如何訪問Ocelot中帶權限驗證的API

• Ocelot.JwtAuthorize：一個基于網關的Jwt驗證包

• .NET Core微服務之基于Ocelot實現API網關服務

• .NET Core微服務之基于Ocelot實現API網關服務（續）

• .NET微服務體系結構中為什么使用Ocelot實現API網關

• Ocelot簡易教程（一）之Ocelot是什么

• Ocelot簡易教程（二）之快速開始1

• Ocelot簡易教程（二）之快速開始2

• Ocelot簡易教程（三）之主要特性及路由詳解

• Ocelot簡易教程（四）之請求聚合以及服務發現

• Ocelot簡易教程（五）之集成IdentityServer認證以及授權

• Ocelot簡易教程（六）之重寫配置文件存儲方式并優化響應數據

• Ocelot簡易教程（七）之配置文件數據庫存儲插件源碼解析

• ASP.NET Core中Ocelot的使用：API網關的應用

• ASP.NET Core中Ocelot的使用：基于Spring Cloud Netflix Eureka的動態路由

• ASP.NET Core中Ocelot的使用：基于服務發現的負載均衡
  

原文地址: https://www.cnblogs.com/jackcao/p/9937213.html

---

.NET社區新聞，深度好文，歡迎訪問公眾號文章匯總 http://www.csharpkit.com

總結

以上是生活随笔為你收集整理的定制Ocelot来满足需求的全部內容，希望文章能夠幫你解決所遇到的問題。

如果覺得生活随笔網站內容還不錯，歡迎將生活随笔推薦給好友。