In today’s world, businesses demand applications that can handle millions of users while ensuring minimal downtime. High-scale and high-availability services are crucial for modern cloud-based applications. .NET 8 brings significant improvements in this space with Extensions.Resilience, which simplifies implementing resilience patterns like retries, circuit breakers, and rate limiters.

Understanding Resilience in High-Scale Systems

Resilience refers to an application’s ability to recover from failures and continue operating smoothly. Failures can be due to network outages, hardware crashes, database timeouts, or API failures. Instead of letting these failures cause system downtime, resilience techniques help services adapt and recover automatically.

What is Extensions.Resilience in .NET 8?

.NET 8 introduces Microsoft.Extensions.Resilience, a library that makes implementing resilience patterns easier. It includes features like:

• Retry Policies – Automatically retrying failed operations.
• Circuit Breakers – Temporarily stopping requests to a failing service to prevent overloading.
• Timeout Policies – Defining how long to wait before canceling an operation.
• Rate Limiting – Controlling the number of requests to prevent system overload.

Understanding Extensions.Http.Resilience

.NET 8 also introduces Microsoft.Extensions.Http.Resilience, which extends resilience capabilities specifically for HTTP-based services. This is particularly useful for microservices, API communication, and external service calls. It provides:

• Preconfigured Resilience Policies for HTTP Clients
• Automatic Integration with HttpClientFactory
• Built-in support for Retry, Circuit Breakers, and Timeouts

Real-World Use Case: E-Commerce Checkout Service

Imagine you are running an e-commerce platform. During peak sales, the checkout service makes API calls to payment gateways, inventory systems, and order processing services. If any of these dependencies fail, a naive implementation would crash or time out, leading to lost sales.

With Extensions.Resilience and Extensions.Http.Resilience, you can implement retry and circuit breaker mechanisms to ensure smooth operation even when external systems have temporary failures.

Implementing Resilience in .NET 8 with C#

1. Install the required packages

      dotnet add package Microsoft.Extensions.Resilience
      dotnet add package Microsoft.Extensions.Http.Resilience
   

2. Configure Resilience Policies for HTTP Requests

      using Microsoft.Extensions.DependencyInjection;
      using Microsoft.Extensions.Http.Resilience;
   
      var services = new ServiceCollection();
   
      services.AddHttpClient("payment-gateway")
          .AddStandardResilienceHandler(); // Adds default retry, circuit breaker, and timeout policies
   
      var provider = services.BuildServiceProvider();
      var httpClientFactory = provider.GetRequiredService<IHttpClientFactory>();
      var httpClient = httpClientFactory.CreateClient("payment-gateway");
   

3. Using Resilience in API Calls

   
      using System.Net.Http;
      using System.Threading.Tasks;
   
      public class CheckoutService
      {
          private readonly HttpClient _httpClient;
   
          public CheckoutService(IHttpClientFactory httpClientFactory)
          {
              _httpClient = httpClientFactory.CreateClient("payment-gateway");
          }
   
          public async Task<string> ProcessPaymentAsync()
          {
              HttpResponseMessage response = await _httpClient.GetAsync("https://paymentgateway.com/pay");
              response.EnsureSuccessStatusCode();
              return await response.Content.ReadAsStringAsync();
          }
      }
   

How This Works:

• Retry: If the payment API fails, the request is retried automatically.
• Circuit Breaker: If too many failures occur, new requests are blocked temporarily.
• Timeouts: Ensures API calls do not hang indefinitely.
• Ensuring Availability: Customers experience fewer checkout failures, and the system self-heals after temporary issues.

What if Microsoft had not introduced Extensions.Resilience and Extensions.Http.Resilience ?

If Microsoft had not introduced Extensions.Resilience and Extensions.Http.Resilience in .NET 8, developers would need to manually implement resilience patterns using third-party libraries like Polly. This would involve writing custom retry logic, circuit breakers, and timeout handling for each HTTP client, increasing complexity and maintenance overhead. Additionally, ensuring consistency across multiple services would require extra effort in configuring and managing these resilience policies. By integrating resilience directly into the .NET ecosystem, Microsoft has simplified service reliability, reducing boilerplate code and making high-availability architectures more accessible to developers.

Conclusion

Building high-scale and high-availability services requires planning for failures. With .NET 8’s Extensions.Resilience and Extensions.Http.Resilience, developers can easily add retry, circuit breaker, and timeout mechanisms to enhance service reliability. Whether handling API failures, database timeouts, or network issues, resilience patterns ensure that your application remains robust even in adverse conditions.

While resilience is mainly about availability, it plays a critical role in supporting scalability by preventing failures from escalating, optimizing resources, and ensuring smooth auto-scaling. A system that scales without resilience is fragile, and a resilient system that doesn’t scale can still become a bottleneck. The best architectures balance both. By implementing these strategies, businesses can provide a seamless experience to users, reduce downtime, and optimize system performance.