Microsoft's cutting-edge, quick, cross-platform, and open-source framework for creating a wide range of applications, from web apps and APIs to console apps and cloud-native microservices, is called.NET Core (now a part of the.NET 5+ unified platform). For novices who wish to comprehend what.NET Core is, how it functions, and the structure of an actual ASP.NET Core project, this article provides the most straightforward explanation of the framework.

1. What is .NET Core?
.NET Core is Microsoft’s next-generation application development framework, built to overcome the limitations of the old .NET Framework.

Why was .NET Core created?
The old .NET Framework could run only on Windows, was heavy, and was not suitable for cloud, containers, and modern architecture.

.NET Core solves all of these issues.

Key Features of .NET Core
1. Cross-Platform
You can develop and run apps on:

• Windows
• Linux
• macOS

You can host apps on IIS, Apache, Nginx, Kestrel, Docker, or the cloud.

2. Open Source

• Available on GitHub
• Anyone can read or contribute to the source code
• Community-driven improvements

3. High Performance
One of the fastest web frameworks in the world
Handles more traffic with less hardware
Perfect for APIs, enterprise apps, and large-scale cloud systems.

4. Lightweight & Modular
You install only what you need using NuGet packages, which makes applications fast and optimized.

5. Built-in Dependency Injection
Dependency Injection (DI) is built into the framework — no need for third-party libraries.

DI makes apps:

• Cleaner
• Easier to test
• More modular

6. Regular Updates
Microsoft releases new versions every year, including LTS (Long-Term Support) versions for stability.

2. ASP.NET vs ASP.NET Core — What’s the Difference?
ASP.NET Core is a complete redesign of ASP.NET — not just a small upgrade.

3. Understanding .NET Core Project Structure

When you create a new ASP.NET Core project, you get several important files and folders. Each plays a special role.
3.1 Program.cs

This is the entry point of your application.

What happens here?
Creates and configures the web host

• Registers services (Database, Logging, Authentication)
• Defines the middleware pipeline
• Maps controllers/endpoints

Think of Program.cs as the “main switchboard” that controls your entire app.

3.2 wwwroot Folder
Everything inside this folder is public.

Used for:

• CSS files
• JavaScript
• Images
• Bootstrap files

A browser can directly access these files using URLs.
wwwroot = Your public website folder.

3.3 Controllers Folder
Controllers:
Receive HTTP requests
Run logic
Return responses (JSON, HTML, etc.)

Example actions:

• GET → Read data
• POST → Create data
• PUT → Update data
• DELETE → Remove data

Controllers are like the reception desk of your app.

3.4 appsettings.json
This is your configuration file.

Used for:

• Database connection strings
• API keys
• Logging settings

Email settings
You can also have:
appsettings.Development.json
appsettings.Production.json
appsettings.json is the “control panel” of your project.

3.5 Other Common Folders
Services
Contains business logic.

Data
Contains:

• DbContext
• Migrations
• Entities

Repositories
Handles database CRUD operations.

DTOs
Used to transfer data safely.

These folders are like the “kitchen and back office.”
They do all the behind-the-scenes work.

4. What is Middleware?
Middleware is the heart of ASP.NET Core.
It is a chain of components that process every request and response.

How Middleware Works?
Request → Middleware 1 → Middleware 2 → Middleware 3 → Controller → Response → Back through same middlewares

Key Points About Middleware

• Runs one-by-one in the order you configure.
• Can modify request or response.
• Can stop the request early (called short-circuiting).
• Used for Logging, Authentication, Routing, Error Handling, etc.

Understanding the Complete Request Pipeline
Let’s break down each stage in the simplest way.

1. Request
When the user sends a request:
Method: GET / POST / PUT / DELETE

URL: /api/products/5

Headers: Auth token, content type

Body: JSON data (for POST/PUT)

2. Logging Middleware
Tracks

• Which URL was called
• Who called
• How long did the request take
• What was the final status code

Useful for

• Debugging
• Performance monitoring
• Auditing

3. Routing
Matches URL → Correct controller action.

Without routing, the application does not know where to send a request.

4. Authentication
Authentication answers:
“Who are you?”

Examples

• JWT Token
• Cookies
• OAuth

If invalid → Later returns 401 Unauthorized

5. Authorization
Authorization answers:
“Are you allowed to do this?”

Example

• Admin-only routes
• Checking user roles
• Checking user claims

If not allowed → 403 Forbidden

6. Controller Execution
Here, the actual processing happens:

• Validating data
• Calling database
• Applying business rules
• Returning response (JSON / HTML)

7. Response
Response goes back through the pipeline and finally returns:

• Status code (200/404/401/403/500)
• Headers
• Body (JSON/HTML)

Why Middleware Order Matters?

• Routing should come before authentication
• Authentication must come before authorization
• Static files should be before MVC
• Error handling needs to be at the top

Incorrect order → Errors like:

• 404 Not Found
• 401 Unauthorized
• Authorization not working

When Things Go Wrong - Quick Fix Guide
401 - Unauthorized
Problem: No identity.
Fix: Check token/cookie + authentication config

403 - Forbidden
Problem: User is known but not allowed.
Fix: Add required roles/claims or change policy

404 - Not Found
Problem: Route not matched.
Fix: Check controller routes and middleware order

Pipeline issues
If things randomly break →
Fix: Ensure correct order:
UseRouting()
UseAuthentication()
UseAuthorization()
MapControllers()

Microsoft created the WCF (Windows Communication Foundation) framework to create service-oriented applications. It enables the transmission of data as asynchronous messages between service endpoints. IIS, Windows services, or even self-hosted apps can host these endpoints. Using a variety of protocols, such as HTTP, TCP, Named Pipes, or MSMQ, developers can create secure, dependable, and transactional services with WCF.

Important WCF Features

• Interoperability: Uses JSON, REST, or SOAP to easily interface with other platforms.
• Multiple Message Patterns: Facilitates duplex, one-way, and request-reply communication.
• Security: Integrated authorization, authentication, and encryption.
• Transaction Support: Guarantees dependable rollback and message delivery.
• Flexible Hosting: Use a console application, Windows Service, or IIS to host.
• Extensibility: It is simple to implement custom behaviors, bindings, and contracts.

Overview of the WCF Architecture
A WCF service is built around four key concepts:

Example: Simple WCF Service

Let’s create a simple “Calculator Service” using WCF.

Step 1. Define the Service Contract
using System.ServiceModel;

[ServiceContract]
public interface ICalculatorService
{
    [OperationContract]
    int Add(int a, int b);

    [OperationContract]
    int Subtract(int a, int b);
}

Step 2. Implement the Service
public class CalculatorService : ICalculatorService
{
    public int Add(int a, int b) => a + b;
    public int Subtract(int a, int b) => a - b;
}

Step 3. Configure Service in App.config
<system.serviceModel>
  <services>
    <service name="WCFDemo.CalculatorService">
      <endpoint address="" binding="basicHttpBinding" contract="WCFDemo.ICalculatorService" />
      <host>
        <baseAddresses>
          <add baseAddress="http://localhost:8080/CalculatorService"/>
        </baseAddresses>
      </host>
    </service>
  </services>
  <behaviors>
    <serviceBehaviors>
      <behavior>
        <serviceMetadata httpGetEnabled="true"/>
        <serviceDebug includeExceptionDetailInFaults="true"/>
      </behavior>
    </serviceBehaviors>
  </behaviors>
</system.serviceModel>

Step 4. Host the Service (Console Example)
using System;
using System.ServiceModel;

class Program
{
    static void Main()
    {
        using (ServiceHost host = new ServiceHost(typeof(CalculatorService)))
        {
            host.Open();
            Console.WriteLine("WCF Calculator Service is running...");
            Console.WriteLine("Press any key to stop.");
            Console.ReadKey();
        }
    }
}

Step 5. Consume the Service (Client Side)
Add a Service Reference in your client project → Enter the service URL (e.g., http://localhost:8080/CalculatorService?wsdl).

Then, you can use:
var client = new CalculatorServiceClient();
Console.WriteLine(client.Add(10, 20));  // Output: 30

Benefits of Using WCF

Common WCF Bindings

Conclusion

WCF remains a powerful framework for building service-oriented, secure, and scalable communication systems.
While modern APIs often use ASP.NET Core Web APIs or gRPC, WCF continues to be a great choice for enterprise-grade distributed applications that require SOAP, WS-Security, and transactional messaging.

A cutting-edge, cross-platform, open-source framework for creating scalable and high-performance online applications is called ASP.NET Core. Its architecture guarantees that developers can achieve high throughput, low latency, and effective resource usage for everything from microservices to enterprise-grade APIs. In order to optimize performance and scalability in your ASP.NET Core applications, we'll go over important tactics, setting advice, and code samples in this post.

Understanding Performance and Scalability
Before diving into implementation, let’s define two crucial concepts:

• Performance: How fast your application responds to a single request.

(Example: Reducing response time from 300ms to 100ms).

• Scalability: How well your application handles increased load.

(Example: Handling 10,000 concurrent users without crashing).

ASP.NET Core achieves both through efficient memory management, asynchronous programming, dependency injection, caching, and built-in support for distributed systems.

Using Asynchronous Programming
The ASP.NET Core runtime is optimized for asynchronous I/O operations. By using the async and await keywords, you can free up threads to handle more requests concurrently.

Example: Asynchronous Controller Action
[ApiController]
[Route("api/[controller]")]
public class ProductsController : ControllerBase
{
    private readonly IProductService _productService;

    public ProductsController(IProductService productService)
    {
        _productService = productService;
    }

    [HttpGet("{id}")]
    public async Task<IActionResult> GetProductById(int id)
    {
        var product = await _productService.GetProductAsync(id);

        if (product == null)
            return NotFound();

        return Ok(product);
    }
}

By using Task<IActionResult> , the thread doesn’t block while waiting for I/O-bound operations such as database queries or API calls. This dramatically improves scalability under heavy load.

Optimize Middleware Pipeline
Middleware components handle each request sequentially. Keep your middleware lightweight and avoid unnecessary processing.

Example: Custom Lightweight Middleware
public class RequestTimingMiddleware
{
    private readonly RequestDelegate _next;
    private readonly ILogger<RequestTimingMiddleware> _logger;

    public RequestTimingMiddleware(RequestDelegate next, ILogger<RequestTimingMiddleware> logger)
    {
        _next = next;
        _logger = logger;
    }

    public async Task InvokeAsync(HttpContext context)
    {
        var start = DateTime.UtcNow;
        await _next(context);
        var elapsed = DateTime.UtcNow - start;

        _logger.LogInformation($"Request took {elapsed.TotalMilliseconds} ms");
    }
}

// Registration in Program.cs
app.UseMiddleware<RequestTimingMiddleware>();

Tip :
Place lightweight middleware at the top (like routing or compression), and heavy middleware (like authentication) lower in the pipeline.

Enable Response Caching
Caching reduces the need to recompute results or hit the database repeatedly. ASP.NET Core provides a built-in Response Caching Middleware .

Example: Enable Response Caching
// In Program.cs
builder.Services.AddResponseCaching();

var app = builder.Build();
app.UseResponseCaching();

app.MapGet("/time", (HttpContext context) =>
{
    context.Response.GetTypedHeaders().CacheControl =
        new Microsoft.Net.Http.Headers.CacheControlHeaderValue()
        {
            Public = true,
            MaxAge = TimeSpan.FromSeconds(30)
        };

    return DateTime.UtcNow.ToString("T");
});

Now, subsequent requests within 30 seconds will be served from cache — drastically improving performance.

Optimize Data Access with EF Core
Database access is often the main bottleneck. Use Entity Framework Core efficiently by applying:

• AsNoTracking() for read-only queries
• Compiled queries for repeated access
• Connection pooling

Example: Using AsNoTracking()
public async Task<IEnumerable<Product>> GetAllProductsAsync()
{
    return await _context.Products
        .AsNoTracking()  // Improves performance
        .ToListAsync();
}

If you frequently run similar queries, consider compiled queries :
private static readonly Func<AppDbContext, int, Task<Product?>> _getProductById =
    EF.CompileAsyncQuery((AppDbContext context, int id) =>
        context.Products.FirstOrDefault(p => p.Id == id));

public Task<Product?> GetProductAsync(int id) =>
    _getProductById(_context, id);

Use Output Compression
Compressing responses before sending them to the client reduces bandwidth usage and speeds up delivery.

Example: Enable Response Compression
// In Program.cs
builder.Services.AddResponseCompression(options =>
{
    options.EnableForHttps = true;
    options.MimeTypes = new[] { "text/plain", "application/json" };
});

var app = builder.Build();
app.UseResponseCompression();

Now all application/json responses will be automatically GZIP-compressed.

Scaling Out with Load Balancing
Performance tuning is not enough when traffic grows. Scalability often involves distributing load across multiple servers using:

• Horizontal Scaling : Adding more servers
• Load Balancers : NGINX, Azure Front Door, AWS ELB, etc.

In distributed systems, session state and caching should be externalized (e.g., Redis).

Example: Configure Distributed Cache (Redis)
builder.Services.AddStackExchangeRedisCache(options =>
{
    options.Configuration = "localhost:6379";
});

public class CacheService
{
    private readonly IDistributedCache _cache;

    public CacheService(IDistributedCache cache)
    {
        _cache = cache;
    }

    public async Task SetCacheAsync(string key, string value)
    {
        await _cache.SetStringAsync(key, value, new DistributedCacheEntryOptions
        {
            AbsoluteExpirationRelativeToNow = TimeSpan.FromMinutes(5)
        });
    }

    public Task<string?> GetCacheAsync(string key) => _cache.GetStringAsync(key);
}

This makes your app stateless, which is essential for load balancing.

Configure Kestrel and Hosting for High Throughput
Kestrel, the built-in ASP.NET Core web server, can handle hundreds of thousands of requests per second when configured properly.

Example: Optimize Kestrel Configuration
builder.WebHost.ConfigureKestrel(options =>
{
    options.Limits.MaxConcurrentConnections = 10000;
    options.Limits.MaxConcurrentUpgradedConnections = 1000;
    options.Limits.RequestHeadersTimeout = TimeSpan.FromSeconds(30);
});

Additionally:

• Use reverse proxy servers (like NGINX or IIS) for static file handling and TLS termination.
• Deploy in containerized environments for auto-scaling (e.g., Kubernetes).
• Use Memory and Object Pooling
• To avoid frequent object allocations and garbage collection, ASP.NET Core supports object pooling .

Example: Using ArrayPool<T>
using System.Buffers;

public class BufferService
{
    public void ProcessData()
    {
        var pool = ArrayPool<byte>.Shared;
        var buffer = pool.Rent(1024); // Rent 1KB buffer

        try
        {
            // Use the buffer
        }
        finally
        {
            pool.Return(buffer);
        }
    }
}

This approach minimizes heap allocations and reduces GC pressure — crucial for performance-sensitive applications.

Minimize Startup Time and Memory Footprint

Avoid unnecessary services in Program.cs .

Use AddSingleton instead of AddTransient where appropriate.

Trim dependencies in *.csproj files.

Example: Minimal API Setup
var builder = WebApplication.CreateBuilder(args);

builder.Services.AddSingleton<IProductService, ProductService>();

var app = builder.Build();

app.MapGet("/products", async (IProductService service) =>
    await service.GetAllProductsAsync());

app.Run();

Minimal APIs reduce boilerplate and improve startup performance.

Monitoring and Benchmarking
You can’t improve what you don’t measure. Use tools like:
dotnet-trace and dotnet-counters

Application Insights

BenchmarkDotNet

Example: Using BenchmarkDotNet
[MemoryDiagnoser]
public class PerformanceTests
{
    private readonly ProductService _service = new();

    [Benchmark]
    public async Task FetchProducts()
    {
        await _service.GetAllProductsAsync();
    }
}

Run this benchmark to identify bottlenecks and memory inefficiencies.

Additional Optimization Tips

• Enable HTTP/2 or HTTP/3 for better parallelism.
• Use CDNs for static assets.
• Employ connection pooling for database and HTTP clients.
• Use IHttpClientFactory to prevent socket exhaustion.

builder.Services.AddHttpClient("MyClient")
.SetHandlerLifetime(TimeSpan.FromMinutes(5));

Conclusion
High performance and scalability in ASP.NET Core are achieved through a combination of asynchronous design , caching , efficient data access , and smart infrastructure choices.
By applying the strategies discussed from optimizing middleware and Kestrel configuration to leveraging Redis and compression — your ASP.NET Core application can handle massive workloads with low latency and high reliability.

Building contemporary online apps and APIs is now easier, lighter, and faster thanks to ASP.NET Core's constant evolution. Developers benefit from significant advancements in OpenAPI integration and Minimal APIs with ASP.NET Core 10.0. With the help of technologies like Swagger UI, Postman, and client SDK generators, these enhancements improve developer experience, streamline API design, and decrease boilerplate. We'll examine what's new, why it matters, and how to make the most of these improvements in this post.

1. Understanding Minimal APIs
Minimal APIs were first introduced in .NET 6 to provide a lightweight way of creating HTTP APIs without the overhead of controllers, attributes, or complex routing. Instead, you define endpoints directly in your Program.cs file.

Here’s a basic minimal API example in .NET 10:
var builder = WebApplication.CreateBuilder(args);
var app = builder.Build();

app.MapGet("/", () => "Hello, ASP.NET Core 10 Minimal APIs!");

app.Run();

Instead of controllers, the request handling logic is expressed inline. This reduces ceremony, making it ideal for:

• Microservices
• Prototypes and demos
• Lightweight REST APIs

2. What’s New in Minimal APIs in .NET 10
ASP.NET Core 10 builds on the foundation of Minimal APIs with:

• Route groups with conventions – Organize endpoints logically.
• Improved parameter binding – Cleaner support for complex types.
• OpenAPI (Swagger) auto-generation improvements – Richer metadata and validation.
• SSE (Server-Sent Events) – Real-time streaming support.
• Enhanced filters and middleware integration – Greater flexibility.

3. OpenAPI in ASP.NET Core 10
OpenAPI (formerly known as Swagger) is the industry standard for describing REST APIs. It enables:

• Documentation: Swagger UI lets developers explore APIs interactively.
• Client SDK generation: Auto-generate clients in C#, TypeScript, Python, etc.
• Validation: Ensures API contracts remain consistent.

In .NET 10, Microsoft has enhanced the OpenAPI package ( Microsoft.AspNetCore.OpenApi ) to work seamlessly with Minimal APIs .

4. Setting Up OpenAPI with Minimal APIs
Add the required package in your project file ( .csproj ):
<ItemGroup>
  <PackageReference Include="Microsoft.AspNetCore.OpenApi" Version="10.0.0" />
  <PackageReference Include="Swashbuckle.AspNetCore" Version="6.5.0" />
</ItemGroup>

Then configure it in Program.cs :
var builder = WebApplication.CreateBuilder(args);

// Add OpenAPI services
builder.Services.AddEndpointsApiExplorer();
builder.Services.AddSwaggerGen();

var app = builder.Build();

// Enable middleware for Swagger
if (app.Environment.IsDevelopment())
{
    app.UseSwagger();
    app.UseSwaggerUI();
}

// Define Minimal API endpoints
app.MapGet("/api/products", () =>
{
    return new[]
    {
        new Product(1, "Laptop", 1200),
        new Product(2, "Phone", 800)
    };
})
.WithName("GetProducts")
.WithOpenApi();

app.Run();

record Product(int Id, string Name, decimal Price);

Key Enhancements in .NET 10

• .WithOpenApi() automatically generates documentation for endpoints.
• Models ( Product ) are described in the OpenAPI schema.
• Swagger UI displays full details without extra configuration.

5. Route Groups in Minimal APIs
.NET 10 introduces Route Groups, which make organizing endpoints easier.
var products = app.MapGroup("/api/products");

products.MapGet("/", () =>
{
    return new List<Product>
    {
        new(1, "Tablet", 500),
        new(2, "Smartwatch", 200)
    };
})
.WithOpenApi();

products.MapGet("/{id:int}", (int id) =>
{
    return new Product(id, "Generated Product", 99.99m);
})
.WithOpenApi();

• All routes under /api/products are grouped.
• Swagger displays them neatly under a single section.

6. OpenAPI Metadata Enrichment
You can enrich OpenAPI docs using endpoint metadata:
products.MapPost("/", (Product product) =>
{
    return Results.Created($"/api/products/{product.Id}", product);
})
.WithName("CreateProduct")
.WithOpenApi(op =>
{
    op.Summary = "Creates a new product";
    op.Description = "Adds a product to the catalog with details like name and price.";
    return op;
});

This makes the Swagger UI highly descriptive with summaries and descriptions .

7. Complex Parameter Binding
Minimal APIs now support cleaner parameter binding.
products.MapPut("/{id:int}", (int id, ProductUpdate update) =>
{
    return Results.Ok(new Product(id, update.Name, update.Price));
})
.WithOpenApi();

record ProductUpdate(string Name, decimal Price);

• Complex request bodies like ProductUpdate are automatically parsed from JSON.
• OpenAPI correctly documents these models.

8. Filters in Minimal APIs
Filters add cross-cutting behaviors like validation or logging without middleware.
products.MapPost("/validate", (Product product) =>
{
    if (string.IsNullOrWhiteSpace(product.Name))
        return Results.BadRequest("Name is required");

    return Results.Ok(product);
})
.AddEndpointFilter(async (context, next) =>
{
    Console.WriteLine("Before executing endpoint");
    var result = await next(context);
    Console.WriteLine("After executing endpoint");
    return result;
})
.WithOpenApi();

Filters improve reusability, and OpenAPI reflects validation details.

9. Server-Sent Events (SSE) in Minimal APIs
Streaming real-time updates is now simpler:
app.MapGet("/notifications", async context =>
{
    context.Response.Headers.Add("Content-Type", "text/event-stream");
    for (int i = 1; i <= 5; i++)
    {
        await context.Response.WriteAsync($"data: Notification {i}\n\n");
        await context.Response.Body.FlushAsync();
        await Task.Delay(1000);
    }
}).WithOpenApi();

Swagger documents the endpoint, though SSE testing is best via Postman or browsers.

10. Security with OpenAPI
You can define security schemes like JWT Bearer authentication in Swagger.
builder.Services.AddSwaggerGen(options =>
{
    options.AddSecurityDefinition("Bearer", new OpenApiSecurityScheme
    {
        In = ParameterLocation.Header,
        Description = "Enter JWT with Bearer prefix",
        Name = "Authorization",
        Type = SecuritySchemeType.ApiKey
    });

    options.AddSecurityRequirement(new OpenApiSecurityRequirement
    {
        {
            new OpenApiSecurityScheme
            {
                Reference = new OpenApiReference
                {
                    Type = ReferenceType.SecurityScheme,
                    Id = "Bearer"
                }
            },
            Array.Empty<string>()
        }
    });
});

Swagger UI now includes a “Authorize” button for JWT authentication.

11. Benefits of OpenAPI & Minimal APIs in .NET 10

• Developer Productivity: Write fewer lines of code.
• Auto Documentation: Swagger/OpenAPI keeps docs updated.
• Integration Ready: Generate SDKs for Angular, React, Python, etc.
• Improved Testing: Swagger UI doubles as an interactive test client.
• Performance: Minimal APIs are faster to start and lighter than MVC controllers.

12. Example: Full Program.cs
var builder = WebApplication.CreateBuilder(args);

builder.Services.AddEndpointsApiExplorer();
builder.Services.AddSwaggerGen();

var app = builder.Build();

if (app.Environment.IsDevelopment())
{
    app.UseSwagger();
    app.UseSwaggerUI();
}

var products = app.MapGroup("/api/products");

products.MapGet("/", () =>
    new List<Product>
    {
        new(1, "Laptop", 1200),
        new(2, "Phone", 800)
    })
.WithOpenApi();

products.MapPost("/", (Product product) =>
    Results.Created($"/api/products/{product.Id}", product))
.WithOpenApi(op =>
{
    op.Summary = "Create a new product";
    op.Description = "Adds a product with name and price to the catalog.";
    return op;
});

app.Run();

record Product(int Id, string Name, decimal Price);

Conclusion
ASP.NET Core 10.0 takes Minimal APIs and OpenAPI integration to the next level. Developers can now:

• Build lightweight APIs with minimal boilerplate.
• Automatically generate and enrich documentation.
• Organize endpoints better with route groups.
• Use filters for cross-cutting concerns.
• Stream updates via SSE.
• Secure APIs with built-in OpenAPI security definitions.

The combination of Minimal APIs and OpenAPI in .NET 10 ensures that APIs are not only fast and efficient but also well-documented, secure, and integration-friendly. This makes ASP.NET Core 10 a powerful choice for microservices, mobile backends, and modern web APIs.