Ocelot是一个.net core框架下的网关的开源项目，下图是官方给出的基础实现图，即把后台的多个服务统一到网关处，前端应用：桌面端，web端，app端都只用访问网关即可。
Ocelot的实现原理就是把客户端对网关的请求(Request)，按照configuration.json的映射配置，转发给对应的后端http service，然后从后端http service获取响应(Response)后，再返回给客户端。当然有了网关后，我们可以在网关这层去做统一验证，也可以在网关处统一作监控。
接下来做个Demo
新建三个asp.net core web aip项目：
OcelotGateway网关项目，端口是5000
DemoAAPI项目A，端口是5001
DemoBAPI项目B，端口是5002
(注：端口可以在每个项目的Properties下的launchSettings.json中修改，发布后的端口可以在Program.cs中用UseUrls(“http://*:5000”)来修改)
对于OcelotGateway：
引用Ocelot的Nuget包：
视图->其他窗口->程序包管理控制台：Install-Package Ocelot
或项目右键“管理Nuget程序包”，在浏览里查找Ocelot进行安装
在OcelotGateway项目中添加一个configuration.json文件，关把它的属性“复制到输出目录”，设成“始终复制”，内容如下：
{
"ReRoutes": [
{
"DownstreamPathTemplate": "/demoaapi/values",
"DownstreamScheme": "http",
"DownstreamPort": 5001,
"DownstreamHost": "localhost",
"UpstreamPathTemplate": "/demoaapi/values",
"UpstreamHttpMethod": [ "Get" ],
"QoSOptions": {
"ExceptionsAllowedBeforeBreaking": 3,
"DurationOfBreak": 10,
"TimeoutValue": 5000
},
"HttpHandlerOptions": {
"AllowAutoRedirect": false,
"UseCookieContainer": false
},
"AuthenticationOptions": {
"AuthenticationProviderKey": "",
"AllowedScopes": []
}
},
{
"DownstreamPathTemplate": "/demobapi/values",
"DownstreamScheme": "http",
"DownstreamPort": 5002,
"DownstreamHost": "localhost",
"UpstreamPathTemplate": "/demobapi/values",
"UpstreamHttpMethod": [ "Get" ],
"QoSOptions": {
"ExceptionsAllowedBeforeBreaking": 3,
"DurationOfBreak": 10,
"TimeoutValue": 5000
},
"HttpHandlerOptions": {
"AllowAutoRedirect": false,
"UseCookieContainer": false
},
"AuthenticationOptions": {
"AuthenticationProviderKey": "",
"AllowedScopes": []
}
}
]
} 接下来对OcelotGateway的Program.cs进行改造
1 using Microsoft.AspNetCore.Hosting;
2
3 using Microsoft.Extensions.Configuration;
4
5 using Microsoft.Extensions.DependencyInjection;
6
7
8
9 namespace OcelotGateway
10
11 {
12
13 public class Program
14
15 {
16
17 public static void Main(string[] args)
18
19 {
20
21 BuildWebHost(args).Run();
22
23 }
24
25 public static IWebHost BuildWebHost(string[] args)
26
27 {
28
29 IWebHostBuilder builder = new WebHostBuilder();
30
31 //注入WebHostBuilder
32
33 return builder.ConfigureServices(service =>
34
35 {
36
37 service.AddSingleton(builder);
38
39 })
40
41 //加载configuration配置文人年
42
43 .ConfigureAppConfiguration(conbuilder =>
44
45 {
46
47 conbuilder.AddJsonFile("configuration.json");
48
49 })
50
51 .UseKestrel()
52
53 .UseUrls("http://*:5000")
54
55 .UseStartup<Startup>()
56
57 .Build();
58
59 }
60
61 }
62
63 } View Code
同时，修改Startup.cs
1 using Microsoft.AspNetCore.Builder;
2
3 using Microsoft.AspNetCore.Hosting;
4
5 using Microsoft.Extensions.Configuration;
6
7 using Microsoft.Extensions.DependencyInjection;
8
9 using Ocelot.DependencyInjection;
10
11 using Ocelot.Middleware;
12
13
14
15 namespace OcelotGateway
16
17 {
18
19 public class Startup
20
21 {
22
23 public Startup(IConfiguration configuration)
24
25 {
26
27 Configuration = configuration;
28
29 }
30
31 public IConfiguration Configuration { get; }
32
33 public void ConfigureServices(IServiceCollection services)
34
35 {
36
37 //注入配置文件，AddOcelot要求参数是IConfigurationRoot类型，所以要作个转换
38
39 services.AddOcelot(Configuration as ConfigurationRoot);
40
41 }
42
43 public void Configure(IApplicationBuilder app, IHostingEnvironment env)
44
45 {
46
47 //添加中间件
48
49 app.UseOcelot().Wait();
50
51 }
52
53 }
54
55 } 为了测试数据好看，我们把DemoAAPI项目和DemoBAPI项目的ValuesController作一下修改：
1 [Route("demoaapi/[controller]")]
2
3 public class ValuesController : Controller
4
5 {
6
7 [HttpGet]
8
9 public IEnumerable<string> Get()
10
11 {
12
13 return new string[] { "DemoA服务", "请求" };
14
15 }
16
17 //……
18
19 }
20
21
22
23 [Route("demobapi/[controller]")]
24
25 public class ValuesController : Controller
26
27 {
28
29 [HttpGet]
30
31 public IEnumerable<string> Get()
32
33 {
34
35 return new string[] { "DemoB服务", "请求" };
36
37 }
38
39 //……
40
41 } 最后在解决方案属性->多个启动项目中，把DemoAAPI，DemoBAPI，OcelotGateway都设成启动，开始启动解决方案，效果如下图
《基于.net core微服务架构视频》
http://edu.51cto.com/course/13342.html
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