A Preliminary Study on ASP.NET Core Api Gateway Ocelot

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This article is reprinted from the WeChat public account "UP Technology Control", the author is conan5566. Please contact the UP Technology Control public account for reprinting this article.

Overview

Ocelot is aimed at people running microservices/service-oriented architectures with .NET that need to have a unified entry point into their systems. In particular I wanted to easily integrate with IdentityServer references and bearer tokens. Ocelot is a bunch of middleware in a specific order. Ocelot manipulates an HttpRequest object into a state specified by its configuration until it reaches the request builder middleware where it creates an HttpRequestMessage object that is used to make a request to a downstream service. The middleware that makes the request is the last thing in the Ocelot pipeline. It does not call the next middleware. There is a piece of middleware that maps an HttpResponseMessage to an HttpResponse object and returns it to the client. Basically, it has a bunch of other functionality.

Code Implementation

1. Create a new API client 1

2. Create a new API gateway test

3. Install Ocelot using nuget

4. Add ConfigureAppConfiguration to the Program file

 public class Program
 {
 public   static void Main(string[] args)
 {
            CreateHostBuilder(args).Build().Run();
 } 
 
 public   static IHostBuilder CreateHostBuilder(string[] args) =>
            Host.CreateDefaultBuilder(args)
            .ConfigureAppConfiguration(conf =>
 {
                conf.AddJsonFile( "ocelot.json" , false , true );
 })
                .ConfigureWebHostDefaults(webBuilder =>
 {
                    webBuilder.UseStartup<Startup>();
 });
 }

5. Startup file configuration

 services.AddOcelot(Configuration); 
 
 app.UseOcelot().Wait();

6. Add the file ocelot.json to the gateway project

 {
 "ReRoutes" : [
 {
 "DownstreamPathTemplate" : "/api/WeatherForecast/GetList" ,
 "DownstreamScheme" : "http" ,
 "DownstreamHostAndPorts" : [
 {
 "Host" : "localhost" ,
 "Port" : 5000
 }
 ],
 "UpstreamPathTemplate" : "/GetList" ,
 "UpstreamHttpMethod" : [ "Get" ]
 }, 
 
 {
 "DownstreamPathTemplate" : "/{everything}" ,
 "DownstreamScheme" : "http" ,
 "DownstreamHostAndPorts" : [
 {
 "Host" : "localhost" ,
 "Port" : 5000
 }
 ],
 "UpstreamPathTemplate" : "/{everything}" ,
 "UpstreamHttpMethod" : [ "Post" ]
 },
 {
 "DownstreamPathTemplate" : "/api/WeatherForecast/GetModel?id={s1}" ,
 "DownstreamScheme" : "http" ,
 "DownstreamHostAndPorts" : [
 {
 "Host" : "localhost" ,
 "Port" : 5000
 }
 ],
 "UpstreamPathTemplate" : "/GetModel?id={s1}" ,
 "UpstreamHttpMethod" : [ "Get" ]
 }
 ]
 }

7. Run and test 2 projects

Code address

https://gitee.com/conanOpenSource_admin/Example/commit/b3b5a6b15a060b46c5ecd2ea31f0d36791cda18c