Http Clients

Overview #

Enhances the built-in HttpClient with an IHttpClient interface with retry policy using Polly and adds a possibility to easily use Consul service discovery and Fabio load balancing mechanisms, as well as switching between the different implementations.

Installation #

dotnet add package Genocs.HTTP

Dependencies #

• Genocs.Core

Usage #

Extend IGenocsBuilder with AddHttpClient() that will register the required services.

public static IGenocsBuilder RegisterGenocs(this IGenocsBuilder builder)
{
    builder.AddHttpClient();
    // Other services.
    
    return builder;
}

Then, simply inject IHttpClient (and optionally HttpClientOptions to resolve services URLS) to execute HTTP requests.

public class SomeService
{
    private readonly string _webServiceUrl;
    private readonly IHttpClient _client;

    public SomeService(IHttpClient _client, HttpClientOptions options)
    {
        _client = _client;
        _webServiceUrl = options.Services["web-service1"];
    }

    public async Task FooAsync()
    {
        var dto = await _client.GetAsync<Dto>($"{_webService1Url}/data");
    }
}

Options #

type - It sets the IHttpClient message handler, if none is specified then the default handler will be used, other possible values: consul, fabio.

retries - The number of HTTP request retries using an exponential backoff.

services - The dictionary (map) of service_name:service_url values that can be used to invoke the other web services without a need to hardcode the configuration URLs, especially useful when service discovery mechanism or load balancer is available.

appsettings.json

"httpClient": {
  "type": "",
  "retries": 2,
  "services": {
    "web-service1": "http://localhost:5050",
    "web-service2": "web-service2-from-dns"
  }
}

Service Discovery #

Overview #

Provides ConsulServiceDiscoveryMessageHandler (used by IHttpClient) that integrates with Consul service discovery mechanism.

Installation #

dotnet add package Genocs.Discovery

Dependencies #

• Genocs.Core
• Genocs.HTTP

Usage #

Extend IGenocsBuilder with AddConsul() that will register the required services.

public static IGenocsBuilder RegisterGenocs(this IGenocsBuilder builder)
{
    builder
        .AddHttpClient()
        .AddConsul();
    // Other services.

    return 
    builder;
}

Options #

enabled - It determines whether Consul integration is going to be available.

url - The URL of the Consul service.

service - The name of the service group (multiple instances of the same service will use the same service name).

address - The address of the service.

port - The port under which the service is available.

pingEnabled - Register health checks from Consul to validate the service availability (if the service will be offline, it will be removed after the pingInterval and removeAfterInterval timeouts).

pingEndpoint - The endpoint that is called when performing the health check by Consul.

appsettings.json

"consul": {
  "enabled": true,
  "url": "http://localhost:8500",
  "service": "some-service",
  "address": "localhost",
  "port": "5000",
  "pingEnabled": true,
  "pingEndpoint": "ping",
  "pingInterval": 3,
  "removeAfterInterval": 3
}

Load Balancing #

Overview #

Provides FabioMessageHandler (used by IHttpClient) that integrates with Fabio load balancer. In order to use Fabio, it is required to configure Consul as described above.

Installation #

dotnet add package Genocs.LoadBalancing

Dependencies #

• Genocs.Core
• Genocs.HTTP
• Genocs.Discovery

Usage #

Extend IGenocsBuilder with AddFabio() that will register the required services.

public static IGenocsBuilder RegisterGenocs(this IGenocsBuilder builder)
{
    builder
        .AddHttpClient()
        .AddConsul()
        .AddFabio();
    // Other services.

    return builder;
}

Options #

enabled - It determines whether Fabio integration is going to be available.

url - The URL of the Fabio service.

service - the name of the service group used for the Consul registration.

appsettings.json

"fabio": {
  "enabled": true,
  "url": "http://localhost:9999",
  "service": "some-service"
}