Microservices in .NET: What They Are And How to Build Them?

Microservices is a modern architecture approach where an application is broken down into a chunks of small, independent, loosely coupled services, each responsible for a specific business functionality

Each microservice:

• Is developed, deployed, and scaled independently.
• Communicates with others via lightweight protocols like HTTP/REST or gRPC.
• Has its own database, ensuring data encapsulation.
• Can be written in the same or different technologies.

Why Use Microservices?

How Are Microservices Implemented in .NET?

In the .NET ecosystem, microservices are typically built using ASP.NET Core or .NET 8 Minimal APIs. Each microservice is usually a self-contained web API hosted independently. Hire .NET developers that have experience working on microservices architecture to ensure seamless implementation or migration. 

Key Components to Build Microservices in .NET:

1. ASP.NET Core / .NET 8 Minimal APIs
   • Use WebApplication or Controllers to define endpoints.
2. Docker
   • Containerize each microservice.
3. API Gateway
   • Use tools like YARP, Ocelot, or Azure API Gateway to route requests.
4. Service Discovery
   • Register services dynamically using tools like Consul, Kubernetes, or Steeltoe.
5. Database per service
   • Use separate databases (SQL/NoSQL) per microservice for data isolation.
6. Communication between services
   • Use:
     • REST for simple APIs
     • gRPC for performance
     • Message brokers (RabbitMQ, Azure Service Bus) for async comms
7. Monitoring & Logging
   • Integrate Serilog, ELK Stack, Prometheus/Grafana, or Application Insights.

Example Architecture

Let’s assume you’re building an e-commerce system. You can break it down into these microservices:

Each of these services is:

• Hosted independently (via Docker or K8s)
• Exposed via its own endpoints
• Communicates with others over HTTP or message queues

Sample Minimal API – OrderService in .NET 8

// Program.cs
var builder = WebApplication.CreateBuilder(args);
builder.Services.AddSingleton<IOrderService, OrderService>();
var app = builder.Build();
app.MapPost("/orders", (Order order, IOrderService service) =>{ var result = service.CreateOrder(order); return Results.Created($"/orders/{result.Id}", result);
});
app.MapGet("/orders/{id}", (int id, IOrderService service) =>{ var order = service.GetOrderById(id); return order != null ? Results.Ok(order) : Results.NotFound();
});
app.Run();

Dockerfile for OrderService

FROM mcr.microsoft.com/dotnet/aspnet:8.0 AS base
WORKDIR /app
EXPOSE 80
FROM mcr.microsoft.com/dotnet/sdk:8.0 AS build
WORKDIR /src
COPY . .
RUN dotnet publish -c Release -o /app/publish
FROM base AS final
WORKDIR /app
COPY --from=build /app/publish .
ENTRYPOINT ["dotnet", "OrderService.dll"]

Service-to-Service Communication Example

From OrderService, you might call ProductService to verify product availability:

public class ProductClient
{ private readonly HttpClient _http; public ProductClient(HttpClient http) => _http = http; public async Task<bool> IsProductAvailable(int productId) { var response = await _http.GetAsync($"http://productservice/products/{productId}/availability"); return response.IsSuccessStatusCode; }
}

Best Practices

• Use OpenTelemetry for distributed tracing.
• Ensure circuit breakers/retries using Polly.
• Use Health Checks (AddHealthChecks) to report service status.
• Apply Authentication & Authorization per service using JWT Bearer tokens.

Final Thoughts

Implementing microservices in .NET allows you to build modular, scalable, and resilient applications. With the power of ASP.NET Core, Minimal APIs, Docker, and modern DevOps practices, .NET is a first-class platform for developing microservices-based systems.