Implementing resilient HTTP requests in C# involves handling various failure scenarios such as network errors, server timeouts, and temporary failures gracefully. You can achieve resilience by implementing retry policies, circuit breakers, and fallback mechanisms. Below is an example of how you can implement resilient HTTP requests using the `Polly` library, which provides comprehensive resilience and transient-fault handling policies for .NET.
Step 1: Install Polly NuGet Package
First, you need to install the `Polly` NuGet package into your project:
dotnet add package Polly
Step 2: Implement Resilient HTTP Client
using System;
using System.Net.Http;
using Polly;
using Polly.Timeout;
public class ResilientHttpClient
{
private readonly HttpClient _httpClient;
private readonly Policy _retryPolicy;
public ResilientHttpClient()
{
_httpClient = new HttpClient();
// Define retry policy with exponential backoff and jitter
_retryPolicy = Policy
.Handle<HttpRequestException>()
.Or<TimeoutRejectedException>()
.WaitAndRetryAsync(3, retryAttempt => TimeSpan.FromSeconds(Math.Pow(2, retryAttempt)) + TimeSpan.FromMilliseconds(new Random().Next(0, 100)));
}
public async Task<string> Get(string url)
{
return await _retryPolicy.ExecuteAsync(async () =>
{
var response = await _httpClient.GetAsync(url);
response.EnsureSuccessStatusCode();
return await response.Content.ReadAsStringAsync();
});
}
}
In this example:
– We create an instance of `HttpClient` to make HTTP requests.
– We define a retry policy using Polly’s `WaitAndRetryAsync` policy. This policy retries the HTTP request in case of `HttpRequestException` or `TimeoutRejectedException`.
– The policy is configured to perform exponential backoff with jitter for retries.
– The `Get` method executes the HTTP request within the retry policy.
Step 3: Usage
class Program
{
static async Task Main(string[] args)
{
var httpClient = new ResilientHttpClient();
string response = await httpClient.Get("https://api.example.com/data");
Console.WriteLine(response);
}
}
This implementation demonstrates a basic example of resilient HTTP requests using Polly in C#. You can customize the retry policy, circuit breaker policies, and other resilience strategies according to your specific requirements and application scenarios.