AspNetCore.ApiGateway

Asp Net Core Api Gateway package.

Packages	Version & Downloads
AspNetCore.ApiGateway
AspNetCore.ApiGateway.Client
ts-aspnetcore-apigateway-client

+ This project has been on-boarded by the .NET Foundation, in the Seed category.

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Background

The microservices architecture uses an Api Gateway as shown below.

The package:

Makes creating an Api Gateway a breeze!!

Features

Swagger
Authorization
Filters
- Action
- Exception
- Result
Load balancing
Response caching
Web sockets
Event sourcing
Request aggregation
Middleware service
Logging
Clients available in
- .NET
- Typescript

Gateway as a RESTful Microservice Facade

Your Gateway API is a microservice which exposes endpoints that are a facade over your backend API endpoints.

GET
HEAD
POST
PUT
PATCH
DELETE

Implementation

In the solution, there are 2 back end APIs : Weather API and Stock API.

For eg. To make a GET call to the backend API, you would set up an Api and a GET Route in your Gateway API's Api Orchestrator.

Then, the client app would make a GET call to the Gateway API which would make a GET call to the backend API using HttpClient.

In your Backend API

Let us say you have a GET endpoint like this.

HTTP GET - /weatherforecast/forecast

In your Gateway API

You add a Route for the backend GET call in the Api Orchrestrator.

You create a backend API with ApiKey called weatherservice for eg. And, a Route with RouteKey called forecast for eg.

So, the call to the Gateway would become:

HTTP GET - /weatherservice/forecast

Note

If you want, you can keep the ApiKey, RouteKey, backend API base url and Route path,

in an appsettings, read it using a Config Service,

and pass it to the Api Orchestrator in the below Create method.

Read more.

Add a reference to the package and...

Create an Api Orchestration.

You create an Api (weatherservice) and add a Route (forecast).

    public static class ApiOrchestration
    {
        public static void Create(IApiOrchestrator orchestrator, IApplicationBuilder app)
        {
            var serviceProvider = app.ApplicationServices;

            var weatherService = serviceProvider.GetService<IWeatherService>();

            var weatherApiClientConfig = weatherService.GetClientConfig();

            orchestrator.StartGatewayHub = true;
            orchestrator.GatewayHubUrl = "https://localhost:44360/GatewayHub";

            orchestrator.AddApi("weatherservice", "http://localhost:63969/")
                                //Get
                                .AddRoute("forecast", GatewayVerb.GET, new RouteInfo { Path = "weatherforecast/forecast", ResponseType = typeof(IEnumerable<WeatherForecast>) })
                                //Head
                                .AddRoute("forecasthead", GatewayVerb.HEAD, new RouteInfo { Path = "weatherforecast/forecast" })
                                //Get with params
                                .AddRoute("typewithparams", GatewayVerb.GET, new RouteInfo {  Path = "weatherforecast/types/{index}"})
                                //Get using custom HttpClient
                                .AddRoute("types", GatewayVerb.GET, new RouteInfo { Path = "weatherforecast/types", ResponseType = typeof(string[]), HttpClientConfig = weatherApiClientConfig })
                                //Get with param using custom HttpClient
                                .AddRoute("type", GatewayVerb.GET, new RouteInfo { Path = "weatherforecast/types/", ResponseType = typeof(WeatherTypeResponse), HttpClientConfig = weatherApiClientConfig })
                                //Get using custom implementation
                                .AddRoute("forecast-custom", GatewayVerb.GET, weatherService.GetForecast)
                                //Post
                                .AddRoute("add", GatewayVerb.POST, new RouteInfo { Path = "weatherforecast/types/add", RequestType = typeof(AddWeatherTypeRequest), ResponseType = typeof(string[])})
                                //Put
                                .AddRoute("update", GatewayVerb.PUT, new RouteInfo { Path = "weatherforecast/types/update", RequestType = typeof(UpdateWeatherTypeRequest), ResponseType = typeof(string[]) })
                                //Patch
                                .AddRoute("patch", GatewayVerb.PATCH, new RouteInfo { Path = "weatherforecast/forecast/patch", ResponseType = typeof(WeatherForecast) })
                                //Delete
                                .AddRoute("remove", GatewayVerb.DELETE, new RouteInfo { Path = "weatherforecast/types/remove/", ResponseType = typeof(string[]) })
                        .AddApi("stockservice", "http://localhost:63967/")
                                .AddRoute("stocks", GatewayVerb.GET, new RouteInfo { Path = "stock", ResponseType = typeof(IEnumerable<StockQuote>) })
                                .AddRoute("stock", GatewayVerb.GET, new RouteInfo { Path = "stock/", ResponseType = typeof(StockQuote) })                                
                        .AddHub("chatservice", ConnectionHelpers.BuildHubConnection, "2f85e3c6-66d2-48a3-8ff7-31a65073558b")
                                .AddRoute("room", new HubRouteInfo { InvokeMethod = "SendMessage", ReceiveMethod = "ReceiveMessage", ReceiveParameterTypes = new Type[] { typeof(string), typeof(string) } })
                        .AddEventSource("eventsourceservice", ConnectionHelpers.BuildEventSourceConnection, "281802b8-6f19-4b9d-820c-9ed29ee127f3")
                                .AddRoute("mystream", new EventSourceRouteInfo { ReceiveMethod = "ReceiveMyStreamEvent", Type = EventSourcingType.EventStore, OperationType = EventSourcingOperationType.PublishSubscribe, StreamName = "my-stream", GroupName = "my-group" });
        }
    }

Hook up in Startup.cs

        public void ConfigureServices(IServiceCollection services)
        {
            services.AddTransient<IWeatherService, WeatherService>();

            //Api gateway
            services.AddApiGateway();

            services.AddControllers();

            services.AddSwaggerGen(c =>
            {
                c.SwaggerDoc("v1", new OpenApiInfo { Title = "My Api Gateway", Version = "v1" });
            });
        }

        public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
            }

            app.UseSwagger();

            app.UseSwaggerUI(c =>
            {
                c.SwaggerEndpoint("/swagger/v1/swagger.json", "My Api Gateway");
            });

            //Api gateway
            app.UseApiGateway(orchestrator => ApiOrchestration.Create(orchestrator, app));

            app.UseHttpsRedirection();

            app.UseRouting();

            app.UseAuthorization();

            app.UseEndpoints(endpoints =>
            {
                //GatewayHub endpoint
                endpoints.MapHub<GatewayHub>("/gatewayhub");
                endpoints.MapControllers();
            });
        }

The Gateway Swagger appears as shown below:

To call the forecast Route on the weather service Api,

you can enter the Api key and Route key into Swagger as below:

This will hit the weatherforecast/forecast endpoint on the backend Weather API.

You can check out how the Api Gateway supported Verbs are used below.

Verbs Usage

You can check out how the Api Gateway's endpoint Authorization support below.

Authorization

Customizations

Customize the default HttpClient used by all the routes, to hit the backend Api.
Customize the default HttpClient which each route uses to hit the backend Api.
Use your own HttpClient for each route.
Use your own custom implementation to hit the backend Api.

For Request aggregation, see this section.

Customizations

Load Balancing

Response Caching

Web Sockets

Event Sourcing

Filters

Middleware Service

Viewing your Gateway's Api Orchestration

Your Gateway's Api Orchestration is published by GET /api/Gateway/orchestration endpoint.

Viewing Api Orchestration

Logging

The Api Gateway uses ILogger<ApiGatewayLog> to create logs.

In your Gateway API project, this can be used to tap into these logs.

Clients

The Api Gateway supports a fixed set of endpoints.

All routes go through these endpoints.

The Client application has to talk to these endpoints of the Api Gateway.

A Client library is provided for:

VeritasSoftware/AspNetCore.ApiGateway

VeritasSoftware

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Repository Details

AspNetCore.ApiGateway