//
// Interfaces/IProductCatalog.cs
//using MicroCommerce.Models;
using Shed.CoreKit.WebApi;
using System;
using System.Collections.Generic;namespace MicroCommerce
{public interface IProductCatalog{IEnumerable<Product> Get();[Route("get/{productId}")]public Product Get(Guid productId);}
}

//
// Interfaces/Models/Product.cs
//using System;namespace MicroCommerce.Models
{public class Product{public Guid Id { get; set; }public string Name { get; set; }public Product Clone(){return new Product{Id = Id,Name = Name};}}
}

//
// Interfaces/IShoppingCart.cs
//using MicroCommerce.Models;
using Shed.CoreKit.WebApi;
using System;
using System.Collections.Generic;namespace MicroCommerce
{public interface IShoppingCart{Cart Get();[HttpPut, Route("addorder/{productId}/{qty}")]Cart AddOrder(Guid productId, int qty);Cart DeleteOrder(Guid orderId);[Route("getevents/{timestamp}")]IEnumerable<CartEvent> GetCartEvents(long timestamp);}
}

//
// Interfaces/IProductCatalog/Order.cs
//using System;namespace MicroCommerce.Models
{public class Order{public Guid Id { get; set; }public Product Product { get; set; }public int Quantity { get; set; }public Order Clone(){return new Order{Id = Id,Product = Product.Clone(),Quantity = Quantity};}}
}

//
// Interfaces/IActivityLogger.cs
//using MicroCommerce.Models;
using System.Collections.Generic;namespace MicroCommerce
{public interface IActivityLogger{IEnumerable<LogEvent> Get(long timestamp);}
}

//
// Interfaces/Models/LogEvent.cs
//namespace MicroCommerce.Models
{public class LogEvent: EventBase{public string Description { get; set; }}
}

//
// Properties/launchSettings.json
//{"iisSettings": {"windowsAuthentication": false,"anonymousAuthentication": true,"iisExpress": {"applicationUrl": "http://localhost:60670","sslPort": 0}},"profiles": {"MicroCommerce.ProductCatalog": {"commandName": "Project","environmentVariables": {"ASPNETCORE_ENVIRONMENT": "Development"},"applicationUrl": "http://localhost:5001"}}
}

将Shed.CoreKit.WebApi nuget软件包安装到项目中，并添加到Interfaces和Middleware 项目的链接。Middleware项目将在下面更详细地描述。

//
// ProductCatalog/ProductCatalog.cs
//using MicroCommerce.Models;
using System;
using System.Collections.Generic;
using System.Linq;namespace MicroCommerce.ProductCatalog
{public class ProductCatalogImpl : IProductCatalog{private Product[] _products = new[]{new Product{ Id = new Guid("6BF3A1CE-1239-4528-8924-A56FF6527595"), Name = "T-shirt" },new Product{ Id = new Guid("6BF3A1CE-1239-4528-8924-A56FF6527596"), Name = "Hoodie" },new Product{ Id = new Guid("6BF3A1CE-1239-4528-8924-A56FF6527597"), Name = "Trousers" }};public IEnumerable<Product> Get(){return _products;}public Product Get(Guid productId){return _products.FirstOrDefault(p => p.Id == productId);}}
}

product目录被存储在静态字段中，以简化示例。当然，在实际的应用程序中，您需要使用一些其他存储，可以通过依赖注入将其作为依赖提供。

//
// ProductCatalog/Setup.cs
//using MicroCommerce.Middleware;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;
using Shed.CoreKit.WebApi;namespace MicroCommerce.ProductCatalog
{public class Startup{public void ConfigureServices(IServiceCollection services){services.AddCorrelationToken();services.AddCors();// register the implementation as dependencyservices.AddTransient<IProductCatalog, ProductCatalogImpl>();services.AddLogging(builder => builder.AddConsole());services.AddRequestLogging();}public void Configure(IApplicationBuilder app, IWebHostEnvironment env){if (env.IsDevelopment()){app.UseDeveloperExceptionPage();}app.UseCorrelationToken();app.UseRequestLogging();app.UseCors(builder =>{builder.AllowAnyOrigin().AllowAnyMethod().AllowAnyHeader();});// bind the registered implementation to the endpointapp.UseWebApiEndpoint<IProductCatalog>();}}
}

这导致以下事实：方法出现在微服务中：

//
// ShoppingCart/ShoppingCart.cs
//using MicroCommerce.Models;
using System;
using System.Collections.Generic;
using System.Linq;namespace MicroCommerce.ShoppingCart
{public class ShoppingCartImpl : IShoppingCart{private static List<Order> _orders = new List<Order>();private static List<CartEvent> _events = new List<CartEvent>();private IProductCatalog _catalog;public ShoppingCartImpl(IProductCatalog catalog){_catalog = catalog;}public Cart AddOrder(Guid productId, int qty){var order = _orders.FirstOrDefault(i => i.Product.Id == productId);if(order != null){order.Quantity += qty;CreateEvent(CartEventTypeEnum.OrderChanged, order);}else{var product = _catalog.Get(productId);if (product != null){order = new Order{Id = Guid.NewGuid(),Product = product,Quantity = qty};_orders.Add(order);CreateEvent(CartEventTypeEnum.OrderAdded, order);}}return Get();}public Cart DeleteOrder(Guid orderId){var order = _orders.FirstOrDefault(i => i.Id == orderId);if(order != null){_orders.Remove(order);CreateEvent(CartEventTypeEnum.OrderRemoved, order);}return Get();}public Cart Get(){return new Cart{Orders = _orders};}public IEnumerable<CartEvent> GetCartEvents(long timestamp){return _events.Where(e => e.Timestamp > timestamp);}private void CreateEvent(CartEventTypeEnum type, Order order){_events.Add(new CartEvent{Timestamp = DateTime.Now.Ticks,Time = DateTime.Now,Order = order.Clone(),Type = type});}}
}

在这里，与ProductCatalog中的一样，我们使用static字段作为存储。但是这个微服务仍然使用调用ProductCatalog来获取有关产品的信息，因此我们将IProductCatalog的链接作为依赖项传递给构造函数。

//
// ShoppingCart/Settings.cs
//using MicroCommerce.Middleware;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;
using Shed.CoreKit.WebApi;
using System.Net.Http;namespace MicroCommerce.ShoppingCart
{public class Startup{public void ConfigureServices(IServiceCollection services){services.AddCorrelationToken();services.AddCors();services.AddTransient<IShoppingCart, ShoppingCartImpl>();services.AddTransient<HttpClient>();// register a dependency binded to the endpointservices.AddWebApiEndpoints(new WebApiEndpoint<IProductCatalog>(new System.Uri("http://localhost:5001")));services.AddLogging(builder => builder.AddConsole());services.AddRequestLogging();}public void Configure(IApplicationBuilder app, IWebHostEnvironment env){if (env.IsDevelopment()){app.UseDeveloperExceptionPage();}app.UseCorrelationToken();app.UseRequestLogging("getevents");app.UseCors(builder =>{builder.AllowAnyOrigin().AllowAnyMethod().AllowAnyHeader();});app.UseWebApiEndpoint<IShoppingCart>();}}
}

AddWebApiEndpoints方法可以采用任意数量的参数，因此可以通过一次调用此方法来配置所有依赖项。

//
// ActivityLogger/ActivityLogger.cs
//using MicroCommerce;
using MicroCommerce.Models;
using System.Collections.Generic;
using System.Linq;namespace MicroCommerce.ActivityLogger
{public class ActivityLoggerImpl : IActivityLogger{private IShoppingCart _shoppingCart;private static long timestamp;private static List<LogEvent> _log = new List<LogEvent>();public ActivityLoggerImpl(IShoppingCart shoppingCart){_shoppingCart = shoppingCart;}public IEnumerable<LogEvent> Get(long timestamp){return _log.Where(i => i.Timestamp > timestamp);}public void ReceiveEvents(){var cartEvents = _shoppingCart.GetCartEvents(timestamp);if(cartEvents.Count() > 0){timestamp = cartEvents.Max(c => c.Timestamp);_log.AddRange(cartEvents.Select(e => new LogEvent{Description = $"{GetEventDesc(e.Type)}: '{e.Order.Product.Name} ({e.Order.Quantity})'"}));}}private string GetEventDesc(CartEventTypeEnum type){switch (type){case CartEventTypeEnum.OrderAdded: return "order added";case CartEventTypeEnum.OrderChanged: return "order changed";case CartEventTypeEnum.OrderRemoved: return "order removed";default: return "unknown operation";}}}
}

它还使用了对另一个微服务(IShoppingCart)的依赖。但是此服务的任务之一是侦听其他服务的事件，因此我们添加了另一个ReceiveEvents() 方法，将从调度程序中调用该方法。我们将其另外添加到项目中。

//
// ActivityLogger/Scheduler.cs
//using Microsoft.Extensions.Hosting;
using System;
using System.Threading;
using System.Threading.Tasks;namespace MicroCommerce.ActivityLogger
{public class Scheduler : BackgroundService{private IServiceProvider ServiceProvider;public Scheduler(IServiceProvider serviceProvider){ServiceProvider = serviceProvider;}protected override Task ExecuteAsync(CancellationToken stoppingToken){Timer timer = new Timer(new TimerCallback(PollEvents), stoppingToken, 2000, 2000);return Task.CompletedTask;}private void PollEvents(object state){try{var logger = ServiceProvider.GetService(typeof(MicroCommerce.IActivityLogger)) as ActivityLoggerImpl;logger.ReceiveEvents();}catch{}}}
}

项目设置与上一段相似。
另外，我们只需要添加以前开发的调度程序。

//
// ActivityLogger/Setup.cs
//using System.Net.Http;
using MicroCommerce;
using MicroCommerce.Middleware;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;
using Shed.CoreKit.WebApi;namespace MicroCommerce.ActivityLogger
{public class Startup{public void ConfigureServices(IServiceCollection services){services.AddCorrelationToken();services.AddCors();services.AddTransient<IActivityLogger, ActivityLoggerImpl>();services.AddTransient<HttpClient>();services.AddWebApiEndpoints(new WebApiEndpoint<IShoppingCart>(new System.Uri("http://localhost:5002")));// register the schedulerservices.AddHostedService<Scheduler>();services.AddLogging(builder => builder.AddConsole());services.AddRequestLogging();}public void Configure(IApplicationBuilder app, IWebHostEnvironment env){if (env.IsDevelopment()){app.UseDeveloperExceptionPage();}app.UseCorrelationToken();app.UseRequestLogging("get");app.UseCors(builder =>{builder.AllowAnyOrigin().AllowAnyMethod().AllowAnyHeader();});app.UseWebApiEndpoint<IActivityLogger>();}}
}

5. WebUI项目，用户界面

//
// WebUI/Setup.cs
//using MicroCommerce.Interfaces;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using Shed.CoreKit.WebApi;
using System.Net.Http;namespace MicroCommerce.Web
{public class Startup{public void ConfigureServices(IServiceCollection services){}public void Configure(IApplicationBuilder app, IWebHostEnvironment env){if (env.IsDevelopment()){app.UseDeveloperExceptionPage();}app.Use(async (context, next) =>{//  when root calls, the start page will be returnedif(string.IsNullOrEmpty(context.Request.Path.Value.Trim('/'))){context.Request.Path = "/index.html";}await next();});app.UseStaticFiles();// add redirects to microservicesapp.UseWebApiRedirect("api/products", new WebApiEndpoint<IProductCatalog>(new System.Uri("http://localhost:5001")));app.UseWebApiRedirect("api/orders", new WebApiEndpoint<IShoppingCart>(new System.Uri("http://localhost:5002")));app.UseWebApiRedirect("api/logs", new WebApiEndpoint<IActivityLogger>(new System.Uri("http://localhost:5003")));}}
}

一切都非常简单。现在，例如，如果UI 发出了对“http://localhost:5000/api/products/get”的请求，它将自动重定向到“http://localhost:5001/get”。当然，为此，微服务必须允许跨域请求，但是我们早些时候已允许这样做（请参阅CORS在微服务的实现中）。

<!DOCTYPE html>  <!-- WebUI/wwwroot/index.html -->
<html>
<head><meta charset="utf-8" /><title></title><link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/bootswatch/4.5.0/materia/bootstrap.min.css" />"<style type="text/css">body {background-color: #0094ff;}.panel {background-color: #FFFFFF;margin-top:20px;padding:10px;border-radius: 4px;}.table .desc {vertical-align: middle;font-weight:bold;}.table .actions {text-align:right;white-space:nowrap;width:40px;}</style><script src="https://code.jquery.com/jquery-3.5.1.min.js"integrity="sha256-9/aliU8dGd2tb6OSsuzixeV4y/faTqgFtohetphbbj0="crossorigin="anonymous"></script><script src="https://cdnjs.cloudflare.com/ajax/libs/knockout/3.5.1/knockout-latest.min.js"></script><script src="../index.js"></script>
</head>
<body><div class="container"><div class="row"><div class="col-12"><div class="panel panel-heading"><div class="panel-heading"><h1>MicroCommerce</h1></div></div></div><div class="col-xs-12 col-md-6"><div class="panel panel-default"><h2>All products</h2><table class="table table-bordered" data-bind="foreach:products"><tr><td data-bind="text:name"></td><td class="actions"><a class="btn btn-primary" data-bind="click:function(){$parent.addorder(id, 1);}">ADD</a></td></tr></table></div></div><div class="col-xs-12 col-md-6"><div class="panel panel-default" data-bind="visible:shoppingCart()"><h2>Shopping cart</h2><table class="table table-bordered" data-bind="foreach:shoppingCart().orders"><tr><td data-bind="text:product.name"></td><td class="actions" data-bind="text:quantity"></td><td class="actions"><a class="btn btn-primary" data-bind="click:function(){$parent.delorder(id);}">DELETE</a></td></tr></table></div></div><div class="col-12"><div class="panel panel-default"><h2>Operations history</h2><!-- ko foreach:logs --><div class="log-item"><span data-bind="text:time"></span><span data-bind="text:description"></span></div><!-- /ko --></div></div></div></div><script src="https://stackpath.bootstrapcdn.com/bootstrap/4.4.1/js/bootstrap.min.js"></script><script>var model = new IndexModel();ko.applyBindings(model);</script>
</body>
</html>

//
// WebUI/wwwroot/index.js
//function request(url, method, data) {return $.ajax({cache: false,dataType: 'json',url: url,data: data ? JSON.stringify(data) : null,method: method,contentType: 'application/json'});
}function IndexModel() {this.products = ko.observableArray([]);this.shoppingCart = ko.observableArray(null);this.logs = ko.observableArray([]);var _this = this;this.getproducts = function () {request('/api/products/get', 'GET').done(function (products) {_this.products(products);console.log("get products: ", products);}).fail(function (err) {console.log("get products error: ", err);});};this.getcart = function () {request('/api/orders/get', 'GET').done(function (cart) {_this.shoppingCart(cart);console.log("get cart: ", cart);}).fail(function (err) {console.log("get cart error: ", err);});};this.addorder = function (id, qty) {request(`/api/orders/addorder/${id}/${qty}`, 'PUT').done(function (cart) {_this.shoppingCart(cart);console.log("add order: ", cart);}).fail(function (err) {console.log("add order error: ", err);});};this.delorder = function (id) {request(`/api/orders/deleteorder?orderId=${id}`, 'DELETE').done(function (cart) {_this.shoppingCart(cart);console.log("del order: ", cart);}).fail(function (err) {console.log("del order error: ", err);});};this.timestamp = Number(0);this.updateLogsInProgress = false;this.updatelogs = function () {if (_this.updateLogsInProgress)return;_this.updateLogsInProgress = true;request(`/api/logs/get?timestamp=${_this.timestamp}`, 'GET').done(function (logs) {if (!logs.length) {return;}ko.utils.arrayForEach(logs, function (item) {_this.logs.push(item);_this.timestamp = Math.max(_this.timestamp, Number(item.timestamp));});console.log("update logs: ", logs, _this.timestamp);}).fail(function (err) {console.log("update logs error: ", err);}).always(function () { _this.updateLogsInProgress = false; });};this.getproducts();this.getcart();this.updatelogs();setInterval(() => _this.updatelogs(), 1000);
}

//
// Middleware/RequestLoggingExt.cs
//using Microsoft.AspNetCore.Builder;
using Microsoft.Extensions.DependencyInjection;namespace MicroCommerce.Middleware
{public static class RequestLoggingExt{private static RequestLoggingOptions Options = new RequestLoggingOptions();public static IApplicationBuilder UseRequestLogging(this IApplicationBuilder builder, params string[] exclude){Options.Exclude = exclude;return builder.UseMiddleware<RequestLoggingMiddleware>();}public static IServiceCollection AddRequestLogging(this IServiceCollection services){return services.AddSingleton(Options);}}internal class RequestLoggingMiddleware{private readonly RequestDelegate _next;private readonly ILogger _logger;private RequestLoggingOptions _options;public RequestLoggingMiddleware(RequestDelegate next, ILoggerFactory loggerFactory, RequestLoggingOptions options){_next = next;_options = options;_logger = loggerFactory.CreateLogger("LoggingMiddleware");}public async Task InvokeAsync(HttpContext context){if(_options.Exclude.Any(i => context.Request.Path.Value.Trim().ToLower().Contains(i))){await _next.Invoke(context);return;}var request = context.Request;_logger.LogInformation($"Incoming request: {request.Method}, {request.Path}, [{HeadersToString(request.Headers)}]");await _next.Invoke(context);var response = context.Response;_logger.LogInformation($"Outgoing response: {response.StatusCode}, [{HeadersToString(response.Headers)}]");}private string HeadersToString(IHeaderDictionary headers){var list = new List<string>();foreach(var key in headers.Keys){list.Add($"'{key}':[{string.Join(';', headers[key])}]");}return string.Join(", ", list);}}internal class RequestLoggingOptions{public string[] Exclude = new string[] { };}
}

一对AddRequestLogging()/UseRequestLogging(...)方法使我们能够在微服务中启用查询日志记录。UseRequestLogging方法还可以采用任意数量的异常路径。我们在ShoppingCart和ActivityLogger中使用它来从日志中排除事件轮询，并避免日志溢出。但是，与其他任何常见功能一样，日记功能也是开发人员的专有责任，并且是在特定项目的框架内实现的。