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@stevejgordon
Let's Talk HTTP in .NET Core
with IHttpClientFactory and Polly
Steve Gordon
@stevejgordon | stevejgordon.co.uk
https://bit.ly/dotnet-http
https://www.meetup.com/dotnetsoutheast
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@stevejgordon
www.stevejgordon.co.uk
• Why do we need IHttpClientFactory?
• How to use IHttpClientFactory
• Outgoing middleware
• Handling transient errors with Polly
• Patterns and recommendations
• HTTP improvements in .NET Core 2.1 to 3.1
NOTE: I'm generally speaking about .NET Core today.
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@stevejgordon
www.stevejgordon.co.uk
public class GitHubController : ControllerBase
{
[HttpGet]
public async Task>> GetAspNetRepos()
{
using (var client = new HttpClient())
{
client.DefaultRequestHeaders.Add("Accept", "application/vnd.github.v3+json");
client.DefaultRequestHeaders.Add("User-Agent", "my-user-agent");
var url = "https://api.github.com/orgs/aspnet/repos";
var request = new HttpRequestMessage(HttpMethod.Get, url);
var response = await _httpClient.SendAsync(request);
var data = await response.Content.ReadAsStringAsync();
return Ok(JsonConvert.DeserializeObject>(data));
}
}
}
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@stevejgordon
www.stevejgordon.co.uk
public class GitHubController : ControllerBase
{
[HttpGet]
public async Task>> GetAspNetRepos()
{
using (var client = new HttpClient())
{
client.DefaultRequestHeaders.Add("Accept", "application/vnd.github.v3+json");
client.DefaultRequestHeaders.Add("User-Agent", "my-user-agent");
var url = "https://api.github.com/orgs/aspnet/repos";
var request = new HttpRequestMessage(HttpMethod.Get, url);
var response = await _httpClient.SendAsync(request);
var data = await response.Content.ReadAsStringAsync();
return Ok(JsonConvert.DeserializeObject>(data));
}
}
}
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@stevejgordon
The Solution
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WHAT'S THE SOLUTION?
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@stevejgordon
www.stevejgordon.co.uk
public class Startup
{
public Startup(IConfiguration configuration)
{
Configuration = configuration;
}
public IConfiguration Configuration { get; }
public void ConfigureServices(IServiceCollection services)
{
services.AddMvc();
}
public void Configure(IApplicationBuilder app, IHostingEnvironment env)
{
app.UseMvc();
}
}
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@stevejgordon
www.stevejgordon.co.uk
public class Startup
{
public Startup(IConfiguration configuration)
{
Configuration = configuration;
}
public IConfiguration Configuration { get; }
public void ConfigureServices(IServiceCollection services)
{
services.AddMvc();
}
public void Configure(IApplicationBuilder app, IHostingEnvironment env)
{
app.UseMvc();
}
}
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@stevejgordon
www.stevejgordon.co.uk
public class Startup
{
public Startup(IConfiguration configuration)
{
Configuration = configuration;
}
public IConfiguration Configuration { get; }
public void ConfigureServices(IServiceCollection services)
{
services.AddSingleton();
services.AddMvc();
}
public void Configure(IApplicationBuilder app, IHostingEnvironment env)
{
app.UseMvc();
}
}
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@stevejgordon
www.stevejgordon.co.uk
public class GitHubController : ControllerBase
{
[HttpGet]
public async Task>> GetAspNetRepos()
{
using (var client = new HttpClient())
{
client.DefaultRequestHeaders.Add("Accept", "application/vnd.github.v3+json");
client.DefaultRequestHeaders.Add("User-Agent", "my-user-agent");
var url = "https://api.github.com/orgs/aspnet/repos";
var request = new HttpRequestMessage(HttpMethod.Get, url);
var response = await client.SendAsync(request);
var data = await response.Content.ReadAsStringAsync();
return Ok(JsonConvert.DeserializeObject>(data));
}
}
}
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@stevejgordon
www.stevejgordon.co.uk
public class GitHubController : ControllerBase
{
private readonly HttpClient _httpClient;
public GitHubController(HttpClient httpClient) => _httpClient = httpClient;
[HttpGet]
public async Task>> GetAspNetRepos()
{
using (var client = new HttpClient())
{
client.DefaultRequestHeaders.Add("Accept", "application/vnd.github.v3+json");
client.DefaultRequestHeaders.Add("User-Agent", "my-user-agent");
var url = "https://api.github.com/orgs/aspnet/repos";
var request = new HttpRequestMessage(HttpMethod.Get, url);
var response = await client.SendAsync(request);
var data = await response.Content.ReadAsStringAsync();
return Ok(JsonConvert.DeserializeObject>(data));
}
}
}
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@stevejgordon
www.stevejgordon.co.uk
public class GitHubController : ControllerBase
{
private readonly HttpClient _httpClient;
public GitHubController(HttpClient httpClient) => _httpClient = httpClient;
[HttpGet]
public async Task>> GetAspNetRepos()
{
using (var client = new HttpClient())
{
client.DefaultRequestHeaders.Add("Accept", "application/vnd.github.v3+json");
client.DefaultRequestHeaders.Add("User-Agent", "my-user-agent");
var url = "https://api.github.com/orgs/aspnet/repos";
var request = new HttpRequestMessage(HttpMethod.Get, url);
var response = await client.SendAsync(request);
var data = await response.Content.ReadAsStringAsync();
return Ok(JsonConvert.DeserializeObject>(data));
}
}
}
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@stevejgordon
www.stevejgordon.co.uk
public class GitHubController : ControllerBase
{
private readonly HttpClient _httpClient;
public GitHubController(HttpClient httpClient) => _httpClient = httpClient;
[HttpGet]
public async Task>> GetAspNetRepos()
{
client.DefaultRequestHeaders.Add("Accept", "application/vnd.github.v3+json");
client.DefaultRequestHeaders.Add("User-Agent", "my-user-agent");
var url = "https://api.github.com/orgs/aspnet/repos";
var request = new HttpRequestMessage(HttpMethod.Get, url);
var response = await client.SendAsync(request);
var data = await response.Content.ReadAsStringAsync();
return Ok(JsonConvert.DeserializeObject>(data));
}
}
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@stevejgordon
www.stevejgordon.co.uk
public class GitHubController : ControllerBase
{
private readonly HttpClient _httpClient;
public GitHubController(HttpClient httpClient) => _httpClient = httpClient;
[HttpGet]
public async Task>> GetAspNetRepos()
{
var url = "https://api.github.com/orgs/aspnet/repos";
var request = new HttpRequestMessage(HttpMethod.Get, url);
request.Headers.Add("Accept", "application/vnd.github.v3+json");
request.Headers.Add("User-Agent", "my-user-agent");
var response = await client.SendAsync(request);
var data = await response.Content.ReadAsStringAsync();
return Ok(JsonConvert.DeserializeObject>(data));
}
}
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@stevejgordon
www.stevejgordon.co.uk
public class GitHubController : ControllerBase
{
private readonly HttpClient _httpClient;
public GitHubController(HttpClient httpClient) => _httpClient = httpClient;
[HttpGet]
public async Task>> GetAspNetRepos()
{
var url = "https://api.github.com/orgs/aspnet/repos";
var request = new HttpRequestMessage(HttpMethod.Get, url);
request.Headers.Add("Accept", "application/vnd.github.v3+json");
request.Headers.Add("User-Agent", "my-user-agent");
var response = await client.SendAsync(request);
var data = await response.Content.ReadAsStringAsync();
return Ok(JsonConvert.DeserializeObject>(data));
}
}
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@stevejgordon
www.stevejgordon.co.uk
public class GitHubController : ControllerBase
{
private readonly HttpClient _httpClient;
public GitHubController(HttpClient httpClient) => _httpClient = httpClient;
[HttpGet]
public async Task>> GetAspNetRepos()
{
var url = "https://api.github.com/orgs/aspnet/repos";
var request = new HttpRequestMessage(HttpMethod.Get, url);
request.Headers.Add("Accept", "application/vnd.github.v3+json");
request.Headers.Add("User-Agent", "my-user-agent");
var response = await _httpClient.SendAsync(request);
var data = await response.Content.ReadAsStringAsync();
return Ok(JsonConvert.DeserializeObject>(data));
}
}
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BUT…
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DNS
(Pre .NET Core 2.1)
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@stevejgordon
www.stevejgordon.co.uk
• Manages the lifetime of HttpMessageHandlers
• Provides a central location for naming and configuring logical
HttpClients
• Codifies the concept of outgoing middleware via delegating
handlers
• Integrates with Polly for transient-fault handling
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CONVERTING OUR CODE
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@stevejgordon
www.stevejgordon.co.uk
public class Startup
{
public Startup(IConfiguration configuration)
{
Configuration = configuration;
}
public IConfiguration Configuration { get; }
public void ConfigureServices(IServiceCollection services)
{
services.AddSingleton();
services.AddMvc();
}
public void Configure(IApplicationBuilder app, IHostingEnvironment env)
{
app.UseMvc();
}
}
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@stevejgordon
www.stevejgordon.co.uk
public class Startup
{
public Startup(IConfiguration configuration)
{
Configuration = configuration;
}
public IConfiguration Configuration { get; }
public void ConfigureServices(IServiceCollection services)
{
services.AddHttpClient();
services.AddMvc();
}
public void Configure(IApplicationBuilder app, IHostingEnvironment env)
{
app.UseMvc();
}
}
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@stevejgordon
www.stevejgordon.co.uk
public class GitHubController : ControllerBase
{
private readonly HttpClient _httpClient;
public GitHubController(HttpClient httpClient) => _httpClient = httpClient;
[HttpGet]
public async Task>> GetAspNetRepos()
{
var url = "https://api.github.com/orgs/aspnet/repos";
var request = new HttpRequestMessage(HttpMethod.Get, url);
request.Headers.Add("Accept", "application/vnd.github.v3+json");
request.Headers.Add("User-Agent", "my-user-agent");
var response = await _httpClient.SendAsync(request);
var data = await response.Content.ReadAsStringAsync();
return Ok(JsonConvert.DeserializeObject>(data));
}
}
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@stevejgordon
www.stevejgordon.co.uk
public class GitHubController : ControllerBase
{
private readonly HttpClient _httpClient;
public GitHubController(HttpClient httpClient) => _httpClient = httpClient;
[HttpGet]
public async Task>> GetAspNetRepos()
{
var url = "https://api.github.com/orgs/aspnet/repos";
var request = new HttpRequestMessage(HttpMethod.Get, url);
request.Headers.Add("Accept", "application/vnd.github.v3+json");
request.Headers.Add("User-Agent", "my-user-agent");
var response = await _httpClient.SendAsync(request);
var data = await response.Content.ReadAsStringAsync();
return Ok(JsonConvert.DeserializeObject>(data));
}
}
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@stevejgordon
www.stevejgordon.co.uk
public class GitHubController : ControllerBase
{
private readonly IHttpClientFactory _factory;
public GitHubController(IHttpClientFactory factory) => _factory = factory;
[HttpGet]
public async Task>> GetAspNetRepos()
{
var url = "https://api.github.com/orgs/aspnet/repos";
var request = new HttpRequestMessage(HttpMethod.Get, url);
request.Headers.Add("Accept", "application/vnd.github.v3+json");
request.Headers.Add("User-Agent", "my-user-agent");
var response = await _httpClient.SendAsync(request);
var data = await response.Content.ReadAsStringAsync();
return Ok(JsonConvert.DeserializeObject>(data));
}
}
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@stevejgordon
www.stevejgordon.co.uk
public class GitHubController : ControllerBase
{
private readonly IHttpClientFactory _factory;
public GitHubController(IHttpClientFactory factory) => _factory = factory;
[HttpGet]
public async Task>> GetAspNetRepos()
{
var url = "https://api.github.com/orgs/aspnet/repos";
var request = new HttpRequestMessage(HttpMethod.Get, url);
request.Headers.Add("Accept", "application/vnd.github.v3+json");
request.Headers.Add("User-Agent", "my-user-agent");
var response = await _httpClient.SendAsync(request);
var data = await response.Content.ReadAsStringAsync();
return Ok(JsonConvert.DeserializeObject>(data));
}
}
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@stevejgordon
www.stevejgordon.co.uk
public class GitHubController : ControllerBase
{
private readonly IHttpClientFactory _factory;
public GitHubController(IHttpClientFactory factory) => _factory = factory;
[HttpGet]
public async Task>> GetAspNetRepos()
{
var url = "https://api.github.com/orgs/aspnet/repos";
var request = new HttpRequestMessage(HttpMethod.Get, url);
request.Headers.Add("Accept", "application/vnd.github.v3+json");
request.Headers.Add("User-Agent", "my-user-agent");
var httpClient = _factory.CreateClient();
var response = await httpClient.SendAsync(request);
var data = await response.Content.ReadAsStringAsync();
return Ok(JsonConvert.DeserializeObject>(data));
}
}
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NAMED CLIENTS
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@stevejgordon
www.stevejgordon.co.uk
public class Startup
{
...
public void ConfigureServices(IServiceCollection services)
{
services.AddHttpClient();
services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_1);
}
public void Configure(IApplicationBuilder app, IHostingEnvironment env)
{ … }
}
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@stevejgordon
www.stevejgordon.co.uk
public class Startup
{
...
public void ConfigureServices(IServiceCollection services)
{
services.AddHttpClient("github", client =>
{
client.BaseAddress = new Uri("https://api.github.com/");
client.DefaultRequestHeaders.Add("Accept", "application/vnd.github.v3+json");
client.DefaultRequestHeaders.Add("User-Agent", "my-user-agent");
});
services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_1);
}
public void Configure(IApplicationBuilder app, IHostingEnvironment env)
{ … }
}
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@stevejgordon
www.stevejgordon.co.uk
public class Startup
{
...
public void ConfigureServices(IServiceCollection services)
{
services.AddHttpClient("github", client =>
{
client.BaseAddress = new Uri("https://api.github.com/");
client.DefaultRequestHeaders.Add("Accept", "application/vnd.github.v3+json");
client.DefaultRequestHeaders.Add("User-Agent", "my-user-agent");
});
services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_1);
}
public void Configure(IApplicationBuilder app, IHostingEnvironment env)
{ … }
}
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@stevejgordon
www.stevejgordon.co.uk
public class Startup
{
...
public void ConfigureServices(IServiceCollection services)
{
services.AddHttpClient("github", client =>
{
client.BaseAddress = new Uri("https://api.github.com/");
client.DefaultRequestHeaders.Add("Accept", "application/vnd.github.v3+json");
client.DefaultRequestHeaders.Add("User-Agent", "my-user-agent");
});
services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_1);
}
public void Configure(IApplicationBuilder app, IHostingEnvironment env)
{ … }
}
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@stevejgordon
www.stevejgordon.co.uk
public class GitHubController : ControllerBase
{
private readonly IHttpClientFactory _factory;
public GitHubController(IHttpClientFactory factory) => _factory = factory;
[HttpGet]
public async Task>> GetAspNetRepos()
{
var url = "https://api.github.com/orgs/aspnet/repos";
var request = new HttpRequestMessage(HttpMethod.Get, url);
request.Headers.Add("Accept", "application/vnd.github.v3+json");
request.Headers.Add("User-Agent", "my-user-agent");
var httpClient = _factory.CreateClient();
var response = await httpClient.SendAsync(request);
var data = await response.Content.ReadAsStringAsync();
return Ok(JsonConvert.DeserializeObject>(data));
}
}
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@stevejgordon
www.stevejgordon.co.uk
public class GitHubController : ControllerBase
{
private readonly IHttpClientFactory _factory;
public GitHubController(IHttpClientFactory factory) => _factory = factory;
[HttpGet]
public async Task>> GetAspNetRepos()
{
var url = "orgs/aspnet/repos";
var request = new HttpRequestMessage(HttpMethod.Get, url);
request.Headers.Add("Accept", "application/vnd.github.v3+json");
request.Headers.Add("User-Agent", "my-user-agent");
var httpClient = _factory.CreateClient();
var response = await httpClient.SendAsync(request);
var data = await response.Content.ReadAsStringAsync();
return Ok(JsonConvert.DeserializeObject>(data));
}
}
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@stevejgordon
www.stevejgordon.co.uk
public class GitHubController : ControllerBase
{
private readonly IHttpClientFactory _factory;
public GitHubController(IHttpClientFactory factory) => _factory = factory;
[HttpGet]
public async Task>> GetAspNetRepos()
{
var url = "orgs/aspnet/repos";
var request = new HttpRequestMessage(HttpMethod.Get, url);
request.Headers.Add("Accept", "application/vnd.github.v3+json");
request.Headers.Add("User-Agent", "my-user-agent");
var httpClient = _factory.CreateClient();
var response = await httpClient.SendAsync(request);
var data = await response.Content.ReadAsStringAsync();
return Ok(JsonConvert.DeserializeObject>(data));
}
}
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@stevejgordon
www.stevejgordon.co.uk
public class GitHubController : ControllerBase
{
private readonly IHttpClientFactory _factory;
public GitHubController(IHttpClientFactory factory) => _factory = factory;
[HttpGet]
public async Task>> GetAspNetRepos()
{
var url = "orgs/aspnet/repos";
var request = new HttpRequestMessage(HttpMethod.Get, url);
var httpClient = _factory.CreateClient();
var response = await httpClient.SendAsync(request);
var data = await response.Content.ReadAsStringAsync();
return Ok(JsonConvert.DeserializeObject>(data));
}
}
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@stevejgordon
www.stevejgordon.co.uk
public class GitHubController : ControllerBase
{
private readonly IHttpClientFactory _factory;
public GitHubController(IHttpClientFactory factory) => _factory = factory;
[HttpGet]
public async Task>> GetAspNetRepos()
{
var url = "orgs/aspnet/repos";
var request = new HttpRequestMessage(HttpMethod.Get, url);
var httpClient = _factory.CreateClient();
var response = await httpClient.SendAsync(request);
var data = await response.Content.ReadAsStringAsync();
return Ok(JsonConvert.DeserializeObject>(data));
}
}
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@stevejgordon
www.stevejgordon.co.uk
public class GitHubController : ControllerBase
{
private readonly IHttpClientFactory _factory;
public GitHubController(IHttpClientFactory factory) => _factory = factory;
[HttpGet]
public async Task>> GetAspNetRepos()
{
var url = "orgs/aspnet/repos";
var request = new HttpRequestMessage(HttpMethod.Get, url);
var httpClient = _factory.CreateClient("github");
var response = await httpClient.SendAsync(request);
var data = await response.Content.ReadAsStringAsync();
return Ok(JsonConvert.DeserializeObject>(data));
}
}
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TYPED CLIENTS
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@stevejgordon
www.stevejgordon.co.uk
public class GitHubClient : IGitHubClient
{
private readonly HttpClient _httpClient;
public GitHubClient(HttpClient client)
{
client.BaseAddress = new Uri("https://api.github.com/");
client.DefaultRequestHeaders.Add("Accept", "application/vnd.github.v3+json");
client.DefaultRequestHeaders.Add("User-Agent", "my_user_agent");
_httpClient = client;
}
public async Task> GetAspNetReposAsync()
{
var url = "orgs/aspnet/repos";
var request = new HttpRequestMessage(HttpMethod.Get, url);
var response = await _httpClient.SendAsync(request);
var data = await response.Content.ReadAsStringAsync();
return JsonConvert.DeserializeObject>(data);
}
}
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@stevejgordon
www.stevejgordon.co.uk
public class GitHubClient : IGitHubClient
{
private readonly HttpClient _httpClient;
public GitHubClient(HttpClient client)
{
client.BaseAddress = new Uri("https://api.github.com/");
client.DefaultRequestHeaders.Add("Accept", "application/vnd.github.v3+json");
client.DefaultRequestHeaders.Add("User-Agent", "my_user_agent");
_httpClient = client;
}
public async Task> GetAspNetReposAsync()
{
var url = "orgs/aspnet/repos";
var request = new HttpRequestMessage(HttpMethod.Get, url);
var response = await _httpClient.SendAsync(request);
var data = await response.Content.ReadAsStringAsync();
return JsonConvert.DeserializeObject>(data);
}
}
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@stevejgordon
www.stevejgordon.co.uk
public class GitHubClient : IGitHubClient
{
private readonly HttpClient _httpClient;
public GitHubClient(HttpClient client)
{
client.BaseAddress = new Uri("https://api.github.com/");
client.DefaultRequestHeaders.Add("Accept", "application/vnd.github.v3+json");
client.DefaultRequestHeaders.Add("User-Agent", "my_user_agent");
_httpClient = client;
}
public async Task> GetAspNetReposAsync()
{
var url = "orgs/aspnet/repos";
var request = new HttpRequestMessage(HttpMethod.Get, url);
var response = await _httpClient.SendAsync(request);
var data = await response.Content.ReadAsStringAsync();
return JsonConvert.DeserializeObject>(data);
}
}
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@stevejgordon
www.stevejgordon.co.uk
public class GitHubClient : IGitHubClient
{
private readonly HttpClient _httpClient;
public GitHubClient(HttpClient client)
{
client.BaseAddress = new Uri("https://api.github.com/");
client.DefaultRequestHeaders.Add("Accept", "application/vnd.github.v3+json");
client.DefaultRequestHeaders.Add("User-Agent", "my_user_agent");
_httpClient = client;
}
public async Task> GetAspNetReposAsync()
{
var url = "orgs/aspnet/repos";
var request = new HttpRequestMessage(HttpMethod.Get, url);
var response = await _httpClient.SendAsync(request);
var data = await response.Content.ReadAsStringAsync();
return JsonConvert.DeserializeObject>(data);
}
}
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@stevejgordon
www.stevejgordon.co.uk
public class Startup
{
...
public void ConfigureServices(IServiceCollection services)
{
services.AddHttpClient("github", client =>
{
client.BaseAddress = new Uri("https://api.github.com/");
client.DefaultRequestHeaders.Add("Accept", "application/vnd.github.v3+json");
client.DefaultRequestHeaders.Add("User-Agent", "my-user-agent");
});
services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_1);
}
public void Configure(IApplicationBuilder app, IHostingEnvironment env)
{ … }
}
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@stevejgordon
www.stevejgordon.co.uk
public class Startup
{
...
public void ConfigureServices(IServiceCollection services)
{
services.AddHttpClient();
services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_1);
}
public void Configure(IApplicationBuilder app, IHostingEnvironment env)
{ … }
}
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@stevejgordon
www.stevejgordon.co.uk
public class GitHubController : ControllerBase
{
private readonly IHttpClientFactory _factory;
public GitHubController(IHttpClientFactory factory) => _factory = factory;
[HttpGet]
public async Task>> GetAspNetRepos()
{
var url = "orgs/aspnet/repos";
var request = new HttpRequestMessage(HttpMethod.Get, url);
var httpClient = _factory.CreateClient("github");
var response = await httpClient.SendAsync(request);
var data = await response.Content.ReadAsStringAsync();
return Ok(JsonConvert.DeserializeObject>(data));
}
}
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@stevejgordon
www.stevejgordon.co.uk
public class GitHubController : ControllerBase
{
private readonly IGitHubClient _gitHubClient;
public GitHubController(IGitHubClient gitHubClient) => _gitHubClient = gitHubClient;
[HttpGet]
public async Task>> GetAspNetRepos()
{
var url = "orgs/aspnet/repos";
var request = new HttpRequestMessage(HttpMethod.Get, url);
var httpClient = _factory.CreateClient("github");
var response = await httpClient.SendAsync(request);
var data = await response.Content.ReadAsStringAsync();
return Ok(JsonConvert.DeserializeObject>(data));
}
}
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@stevejgordon
www.stevejgordon.co.uk
public class GitHubController : ControllerBase
{
private readonly IGitHubClient _gitHubClient;
public GitHubController(IGitHubClient gitHubClient) => _gitHubClient = gitHubClient;
[HttpGet]
public async Task>> GetAspNetRepos()
{
var url = "orgs/aspnet/repos";
var request = new HttpRequestMessage(HttpMethod.Get, url);
var httpClient = _factory.CreateClient("github");
var response = await httpClient.SendAsync(request);
var data = await response.Content.ReadAsStringAsync();
return Ok(JsonConvert.DeserializeObject>(data));
}
}
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@stevejgordon
www.stevejgordon.co.uk
public class GitHubController : ControllerBase
{
private readonly IGitHubClient _gitHubClient;
public GitHubController(IGitHubClient gitHubClient) => _gitHubClient = gitHubClient;
[HttpGet]
public async Task>> GetAspNetRepos()
{
var data = await _gitHubClient.GetAspNetReposAsync();
return Ok(data);
}
}
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@stevejgordon
www.stevejgordon.co.uk
https://api.github.com
HttpClient
H t t p R e q u e s t M e s s a g e
H t t p R e s p o n s e M e s s a g e
Our Application
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@stevejgordon
www.stevejgordon.co.uk
Outer Handler
Middle Handler
Inner Handler
HttpClientHandler
SocketsHttpHandler
HttpClient
H t t p R e q u e s t M e s s a g e
H t t p R e s p o n s e M e s s a g e
https://api.github.com
Our Application
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No content
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@stevejgordon
www.stevejgordon.co.uk
public class StatusCodeMetricHandler : DelegatingHandler
{
private readonly IMonitoringService _monitoringService;
public StatusCodeMetricHandler(IMonitoringService monitoringService) =>
_monitoringService = monitoringService;
protected override async Task SendAsync(
HttpRequestMessage request,
CancellationToken ct)
{
// note: we could do things with the request before passing it along
var response = await base.SendAsync(request, ct);
_monitoringService.RecordStatusCodeMetric((int)response.StatusCode);
return response;
}
}
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@stevejgordon
www.stevejgordon.co.uk
public class StatusCodeMetricHandler : DelegatingHandler
{
private readonly IMonitoringService _monitoringService;
public StatusCodeMetricHandler(IMonitoringService monitoringService) =>
_monitoringService = monitoringService;
protected override async Task SendAsync(
HttpRequestMessage request,
CancellationToken ct)
{
// note: we could do things with the request before passing it along
var response = await base.SendAsync(request, ct);
_monitoringService.RecordStatusCodeMetric((int)response.StatusCode);
return response;
}
}
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@stevejgordon
www.stevejgordon.co.uk
public class StatusCodeMetricHandler : DelegatingHandler
{
private readonly IMonitoringService _monitoringService;
public StatusCodeMetricHandler(IMonitoringService monitoringService) =>
_monitoringService = monitoringService;
protected override async Task SendAsync(
HttpRequestMessage request,
CancellationToken ct)
{
// note: we could do things with the request before passing it along
var response = await base.SendAsync(request, ct);
_monitoringService.RecordStatusCodeMetric((int)response.StatusCode);
return response;
}
}
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@stevejgordon
www.stevejgordon.co.uk
public class StatusCodeMetricHandler : DelegatingHandler
{
private readonly IMonitoringService _monitoringService;
public StatusCodeMetricHandler(IMonitoringService monitoringService) =>
_monitoringService = monitoringService;
protected override async Task SendAsync(
HttpRequestMessage request,
CancellationToken ct)
{
// note: we could do things with the request before passing it along
var response = await base.SendAsync(request, ct);
_monitoringService.RecordStatusCodeMetric((int)response.StatusCode);
return response;
}
}
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@stevejgordon
www.stevejgordon.co.uk
public class StatusCodeMetricHandler : DelegatingHandler
{
private readonly IMonitoringService _monitoringService;
public StatusCodeMetricHandler(IMonitoringService monitoringService) =>
_monitoringService = monitoringService;
protected override async Task SendAsync(
HttpRequestMessage request,
CancellationToken ct)
{
// note: we could do things with the request before passing it along
var response = await base.SendAsync(request, ct);
_monitoringService.RecordStatusCodeMetric((int)response.StatusCode);
return response;
}
}
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@stevejgordon
www.stevejgordon.co.uk
public class StatusCodeMetricHandler : DelegatingHandler
{
private readonly IMonitoringService _monitoringService;
public StatusCodeMetricHandler(IMonitoringService monitoringService) =>
_monitoringService = monitoringService;
protected override async Task SendAsync(
HttpRequestMessage request,
CancellationToken ct)
{
// note: we could do things with the request before passing it along
var response = await base.SendAsync(request, ct);
_monitoringService.RecordStatusCodeMetric((int)response.StatusCode);
return response;
}
}
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@stevejgordon
www.stevejgordon.co.uk
public class Startup
{
...
public void ConfigureServices(IServiceCollection services)
{
services.AddHttpClient();
services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_1);
}
public void Configure(IApplicationBuilder app, IHostingEnvironment env)
{ … }
}
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@stevejgordon
www.stevejgordon.co.uk
public class Startup
{
...
public void ConfigureServices(IServiceCollection services)
{
services.AddTransient();
services.AddTransient();
services.AddHttpClient()
.AddHttpMessageHandler();
services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_1);
}
public void Configure(IApplicationBuilder app, IHostingEnvironment env)
{ … }
}
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@stevejgordon
www.stevejgordon.co.uk
public class Startup
{
...
public void ConfigureServices(IServiceCollection services)
{
services.AddTransient();
services.AddTransient();
services.AddHttpClient()
.AddHttpMessageHandler();
services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_1);
}
public void Configure(IApplicationBuilder app, IHostingEnvironment env)
{ … }
}
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@stevejgordon
www.stevejgordon.co.uk
• Polly is a .NET resilience and transient-fault-handling library
• Integrates easily with IHttpClientFactory
• Retry
• Circuit-breaker
• Timeout
• Bulkhead isolation
• Cache
• Fallback
• PolicyWrap
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No content
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@stevejgordon
www.stevejgordon.co.uk
public class Startup
{
...
public void ConfigureServices(IServiceCollection services)
{
services.AddTransient();
services.AddTransient();
services.AddHttpClient()
.AddHttpMessageHandler();
services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_1);
}
public void Configure(IApplicationBuilder app, IHostingEnvironment env)
{ … }
}
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@stevejgordon
www.stevejgordon.co.uk
public class Startup
{
...
public void ConfigureServices(IServiceCollection services)
{
services.AddTransient();
services.AddTransient();
services.AddHttpClient()
.AddTransientHttpErrorPolicy(builder =>
builder.WaitAndRetryAsync(3, retryCount =>
TimeSpan.FromSeconds(Math.Pow(2, retryCount))))
.AddHttpMessageHandler();
services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_1);
}
public void Configure(IApplicationBuilder app, IHostingEnvironment env)
{ … }
}
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@stevejgordon
www.stevejgordon.co.uk
public class Startup
{
...
public void ConfigureServices(IServiceCollection services)
{
services.AddTransient();
services.AddTransient();
services.AddHttpClient()
.AddTransientHttpErrorPolicy(builder =>
builder.WaitAndRetryAsync(3, retryCount =>
TimeSpan.FromSeconds(Math.Pow(2, retryCount))))
.AddHttpMessageHandler();
services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_1);
}
public void Configure(IApplicationBuilder app, IHostingEnvironment env)
{ … }
}
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@stevejgordon
www.stevejgordon.co.uk
public class Startup
{
...
public void ConfigureServices(IServiceCollection services)
{
services.AddTransient();
services.AddTransient();
services.AddHttpClient()
.AddTransientHttpErrorPolicy(builder =>
builder.WaitAndRetryAsync(3, retryCount =>
TimeSpan.FromSeconds(Math.Pow(2, retryCount))))
.AddHttpMessageHandler();
services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_1);
}
public void Configure(IApplicationBuilder app, IHostingEnvironment env)
{ … }
}
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@stevejgordon
www.stevejgordon.co.uk
public class Startup
{
...
public void ConfigureServices(IServiceCollection services)
{
services.AddTransient();
services.AddTransient();
services.AddHttpClient()
.AddTransientHttpErrorPolicy(builder =>
builder.WaitAndRetryAsync(3, retryCount =>
TimeSpan.FromSeconds(Math.Pow(2, retryCount))))
.AddHttpMessageHandler();
services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_1);
}
public void Configure(IApplicationBuilder app, IHostingEnvironment env)
{ … }
}
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@stevejgordon
www.stevejgordon.co.uk
public class Startup
{
...
public void ConfigureServices(IServiceCollection services)
{
services.AddTransient();
services.AddTransient();
services.AddHttpClient()
.AddTransientHttpErrorPolicy(builder =>
builder.WaitAndRetryAsync(3, retryCount =>
TimeSpan.FromSeconds(Math.Pow(2, retryCount))))
.AddHttpMessageHandler();
services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_1);
}
public void Configure(IApplicationBuilder app, IHostingEnvironment env)
{ … }
}
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OTHER HTTP TIPS
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No content
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@stevejgordon
www.stevejgordon.co.uk
public class GitHubClient : IGitHubClient
{
private readonly HttpClient _httpClient;
public GitHubClient(HttpClient client)
{
client.BaseAddress = new Uri("https://api.github.com/");
client.DefaultRequestHeaders.Add("Accept", "application/vnd.github.v3+json");
client.DefaultRequestHeaders.Add("User-Agent", "my_user_agent");
_httpClient = client;
}
public async Task> GetAspNetReposAsync()
{
var url = "orgs/aspnet/repos";
var request = new HttpRequestMessage(HttpMethod.Get, url);
var response = await _httpClient.SendAsync(request);
var data = await response.Content.ReadAsStringAsync();
return JsonConvert.DeserializeObject>(data);
}
}
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@stevejgordon
www.stevejgordon.co.uk
public class GitHubClient : IGitHubClient
{
private readonly HttpClient _httpClient;
public GitHubClient(HttpClient client)
{
client.BaseAddress = new Uri("https://api.github.com/");
client.DefaultRequestHeaders.Add("Accept", "application/vnd.github.v3+json");
client.DefaultRequestHeaders.Add("User-Agent", "my_user_agent");
_httpClient = client;
}
public async Task> GetAspNetReposAsync()
{
var url = "orgs/aspnet/repos";
var request = new HttpRequestMessage(HttpMethod.Get, url);
var response = await _httpClient.SendAsync(request);
var data = await response.Content.ReadAsStringAsync();
return JsonConvert.DeserializeObject>(data);
}
}
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@stevejgordon
www.stevejgordon.co.uk
public class GitHubClient : IGitHubClient
{
private readonly HttpClient _httpClient;
public GitHubClient(HttpClient client)
{
client.BaseAddress = new Uri("https://api.github.com/");
client.DefaultRequestHeaders.Add("Accept", "application/vnd.github.v3+json");
client.DefaultRequestHeaders.Add("User-Agent", "my_user_agent");
_httpClient = client;
}
public async Task> GetAspNetReposAsync()
{
var url = "orgs/aspnet/repos";
var request = new HttpRequestMessage(HttpMethod.Get, url);
var response = await _httpClient.SendAsync(request);
return await response.Content.ReadAsAsync>();
}
}
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No content
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@stevejgordon
www.stevejgordon.co.uk
public class GitHubClient : IGitHubClient
{
// ctor - hidden for brevity ...
public async Task> GetAspNetReposAsync()
{
var url = "orgs/aspnet/repos";
var request = new HttpRequestMessage(HttpMethod.Get, url);
var response = await _httpClient.SendAsync(request);
return await response.Content.ReadAsAsync>();
}
}
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@stevejgordon
www.stevejgordon.co.uk
public class GitHubClient : IGitHubClient
{
// ctor - hidden for brevity ...
public async Task> GetAspNetReposAsync()
{
var url = "orgs/aspnet/repos";
var request = new HttpRequestMessage(HttpMethod.Get, url);
var response = await _httpClient.SendAsync(request);
response.EnsureSuccessStatusCode();
return await response.Content.ReadAsAsync>();
}
}
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@stevejgordon
www.stevejgordon.co.uk
public class GitHubClient : IGitHubClient
{
// ctor - hidden for brevity ...
public async Task> GetAspNetReposAsync()
{
var url = "orgs/aspnet/repos";
var request = new HttpRequestMessage(HttpMethod.Get, url);
var response = await _httpClient.SendAsync(request);
return response.IsSuccessStatusCode
? await response.Content.ReadAsAsync>()
: Array.Empty();
}
}
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@stevejgordon
www.stevejgordon.co.uk
public class GitHubClient : IGitHubClient
{
private readonly HttpClient _httpClient;
public GitHubClient(HttpClient client)
{
// hidden for brevity ...
}
public async Task> GetAspNetReposAsync()
{
var url = "orgs/aspnet/repos";
var request = new HttpRequestMessage(HttpMethod.Get, url);
var response = await _httpClient.SendAsync(request);
return response.IsSuccessStatusCode
? await response.Content.ReadAsAsync>()
: Array.Empty();
}
}
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@stevejgordon
www.stevejgordon.co.uk
public class GitHubClient : IGitHubClient
{
private readonly HttpClient _httpClient;
public GitHubClient(HttpClient client)
{
// hidden for brevity ...
}
public async Task> GetAspNetReposAsync(CancellationToken ct = default)
{
var url = "orgs/aspnet/repos";
var request = new HttpRequestMessage(HttpMethod.Get, url);
var response = await _httpClient.SendAsync(request);
return response.IsSuccessStatusCode
? await response.Content.ReadAsAsync>()
: Array.Empty();
}
}
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@stevejgordon
www.stevejgordon.co.uk
public class GitHubClient : IGitHubClient
{
private readonly HttpClient _httpClient;
public GitHubClient(HttpClient client)
{
// hidden for brevity ...
}
public async Task> GetAspNetReposAsync(CancellationToken ct = default)
{
var url = "orgs/aspnet/repos";
var request = new HttpRequestMessage(HttpMethod.Get, url);
ct.ThrowIfCancellationRequested();
var response = await _httpClient.SendAsync(request);
return response.IsSuccessStatusCode
? await response.Content.ReadAsAsync>()
: Array.Empty();
}
}
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@stevejgordon
www.stevejgordon.co.uk
public class GitHubClient : IGitHubClient
{
private readonly HttpClient _httpClient;
public GitHubClient(HttpClient client)
{
// hidden for brevity ...
}
public async Task> GetAspNetReposAsync(CancellationToken ct = default)
{
var url = "orgs/aspnet/repos";
var request = new HttpRequestMessage(HttpMethod.Get, url);
ct.ThrowIfCancellationRequested();
var response = await _httpClient.SendAsync(request, ct);
return response.IsSuccessStatusCode
? await response.Content.ReadAsAsync>()
: Array.Empty();
}
}
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@stevejgordon
www.stevejgordon.co.uk
public class GitHubClient : IGitHubClient
{
private readonly HttpClient _httpClient;
public GitHubClient(HttpClient client)
{
// hidden for brevity ...
}
public async Task> GetAspNetReposAsync(CancellationToken ct = default)
{
var url = "orgs/aspnet/repos";
var request = new HttpRequestMessage(HttpMethod.Get, url);
ct.ThrowIfCancellationRequested();
var response = await _httpClient.SendAsync(request, ct);
return response.IsSuccessStatusCode
? await response.Content.ReadAsAsync>(ct)
: Array.Empty();
}
}
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@stevejgordon
www.stevejgordon.co.uk
public class GitHubController : ControllerBase
{
private readonly IGitHubClient _gitHubClient;
public GitHubController(IGitHubClient gitHubClient) => _gitHubClient = gitHubClient;
[HttpGet]
public async Task>> GetAspNetRepos()
{
var data = await _gitHubClient.GetAspNetReposAsync();
return Ok(data);
}
}
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@stevejgordon
www.stevejgordon.co.uk
public class GitHubController : ControllerBase
{
private readonly IGitHubClient _gitHubClient;
public GitHubController(IGitHubClient gitHubClient) => _gitHubClient = gitHubClient;
[HttpGet]
public async Task>> GetAspNetRepos(CancellationToken ct)
{
var data = await _gitHubClient.GetAspNetReposAsync(ct);
return Ok(data);
}
}
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@stevejgordon
www.stevejgordon.co.uk
public class GitHubController : ControllerBase
{
private readonly IGitHubClient _gitHubClient;
public GitHubController(IGitHubClient gitHubClient) => _gitHubClient = gitHubClient;
[HttpGet]
public async Task>> GetAspNetRepos(CancellationToken ct)
{
var data = await _gitHubClient.GetAspNetReposAsync(ct);
return Ok(data);
}
}
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No content
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@stevejgordon
www.stevejgordon.co.uk
public class GitHubClient : IGitHubClient
{
// ctor - hidden for brevity ...
public async Task> GetAspNetReposAsync(CancellationToken ct = default)
{
var req = new HttpRequestMessage(HttpMethod.Get, "orgs/aspnet/repos");
ct.ThrowIfCancellationRequested();
var response = await _httpClient.SendAsync(req, ct);
return response.IsSuccessStatusCode
? await response.Content.ReadAsAsync>(ct)
: Array.Empty();
}
}
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@stevejgordon
www.stevejgordon.co.uk
public class GitHubClient : IGitHubClient
{
// ctor - hidden for brevity ...
public async Task> GetAspNetReposAsync(CancellationToken ct = default)
{
var req = new HttpRequestMessage(HttpMethod.Get, "orgs/aspnet/repos");
ct.ThrowIfCancellationRequested();
var response = await _httpClient.SendAsync(req, HttpCompletionOption.ResponseHeadersRead, ct);
return response.IsSuccessStatusCode
? await response.Content.ReadAsAsync>(ct)
: Array.Empty();
}
}
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@stevejgordon
www.stevejgordon.co.uk
public class GitHubClient : IGitHubClient
{
// ctor - hidden for brevity ...
public async Task> GetAspNetReposAsync(CancellationToken ct = default)
{
var req = new HttpRequestMessage(HttpMethod.Get, "orgs/aspnet/repos");
ct.ThrowIfCancellationRequested();
var response = await _httpClient.SendAsync(req, HttpCompletionOption.ResponseHeadersRead, ct);
try
{
return response.IsSuccessStatusCode
? await response.Content.ReadAsAsync>(ct)
: Array.Empty();
}
finally
{
response.Dispose();
}
}
}
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No content
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@stevejgordon
www.stevejgordon.co.uk
• HttpClient (using IHttpClientFactory) – No effect
• HttpClient (without IHttpClientFactory) – Generally never
• HttpRequestMessage – Only has an effect (today) if sending
StreamContent
• HttpResponseMessage – No effect unless using ResponseHeadersRead
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@stevejgordon
www.stevejgordon.co.uk
• Built on top of System.Net.Sockets
• Managed code
• Elimination of platform dependencies on libcurl (for Linux) and
WinHTTP (for Windows)
• Consistent behaviour across platforms.
• Enabled by default in .NET Core 2.1+ (No HTTP/2 support until
3.0)
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@stevejgordon
www.stevejgordon.co.uk
• PooledConnectionLifetime similar to ServicePointManager
• Set the max lifetime for a connection
• Also possible to set the PooledConnectionIdleTimeout
• Re-use the same HttpClient and handler chain without DNS
concerns
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@stevejgordon
www.stevejgordon.co.uk
• HTTP/2 is supported (primarily for gRPC scenarios)
• HTTP/2 is not enabled by default
• HttpClient now includes a Version property which applies to all
messages sent via that client (HTTP/1.1 by default)
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@stevejgordon
www.stevejgordon.co.uk
• Use IHttpClientFactory in .NET Core 2.1+
• Use Polly for transient-fault handling
• Beware content.ReadAsStringAsync and client.GetStringAsync
• Expect and handle errors
• Pass cancellation tokens
• Dispose appropriately (generally not required)
• Go enjoy talking HTTP! ☺
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@stevejgordon
www.stevejgordon.co.uk
@stevejgordon | stevejgordon.co.uk
http://bit.ly/dotnet-http
https://www.meetup.com/dotnetsoutheast