Introduction to ASP.NET Core

1┌──────────────────────┬─────────────────────────────┐
2│ Feature              │ ASP.NET Core                │
3├──────────────────────┼─────────────────────────────┤
4│ Platform             │ Windows, Linux, macOS       │
5│ Performance          │ Very high (Kestrel server)  │
6│ Dependency Injection │ Built-in                    │
7│ Configuration        │ Multiple providers          │
8│ Hosting              │ Self-hosted or IIS/Nginx    │
9│ Updates              │ NuGet packages              │
10│ Open Source          │ Yes (MIT License)           │
11└──────────────────────┴─────────────────────────────┘

1# Windows (using winget)
2winget install Microsoft.DotNet.SDK.8
3
4# macOS (using Homebrew)
5brew install --cask dotnet-sdk
6
7# Linux (Ubuntu)
8sudo apt-get update
9sudo apt-get install -y dotnet-sdk-8.0
10
11# Verify installation
12dotnet --version
13# Output: 8.0.100

1# Create a new Web API project
2dotnet new webapi -n MyApi -o MyApi
3
4# Create a minimal API project
5dotnet new web -n MinimalApi -o MinimalApi
6
7# Create an MVC project
8dotnet new mvc -n MyMvcApp -o MyMvcApp
9
10# List all available templates
11dotnet new list
12
13# Common templates:
14# webapi      - ASP.NET Core Web API
15# web         - ASP.NET Core Empty (Minimal)
16# mvc         - ASP.NET Core MVC
17# razor       - ASP.NET Core Razor Pages
18# blazorserver - Blazor Server App
19# blazorwasm  - Blazor WebAssembly App

1# Navigate to project directory
2cd MyApi
3
4# Restore dependencies
5dotnet restore
6
7# Build the project
8dotnet build
9
10# Run the application
11dotnet run
12
13# Run with hot reload (development)
14dotnet watch run
15
16# Run with specific environment
17ASPNETCORE_ENVIRONMENT=Development dotnet run
18
19# Output:
20# info: Microsoft.Hosting.Lifetime[14]
21#       Now listening on: https://localhost:5001
22#       Now listening on: http://localhost:5000
23# info: Microsoft.Hosting.Lifetime[0]
24#       Application started. Press Ctrl+C to shut down.

1MyApi/
2├── Controllers/              # API Controllers
3│   └── WeatherForecastController.cs
4├── Properties/
5│   └── launchSettings.json   # Development settings
6├── appsettings.json          # Application configuration
7├── appsettings.Development.json
8├── Program.cs                # Application entry point
9└── MyApi.csproj              # Project file

1// Program.cs - Modern .NET 8 style
2var builder = WebApplication.CreateBuilder(args);
3
4// Add services to the container
5builder.Services.AddControllers();
6builder.Services.AddEndpointsApiExplorer();
7builder.Services.AddSwaggerGen();
8
9var app = builder.Build();
10
11// Configure the HTTP request pipeline
12if (app.Environment.IsDevelopment())
13{
14    app.UseSwagger();
15    app.UseSwaggerUI();
16}
17
18app.UseHttpsRedirection();
19app.UseAuthorization();
20app.MapControllers();
21
22app.Run();

1using Microsoft.AspNetCore.Mvc;
2
3namespace MyApi.Controllers;
4
5[ApiController]
6[Route("api/[controller]")]
7public class WeatherForecastController : ControllerBase
8{
9    private static readonly string[] Summaries = new[]
10    {
11        "Freezing", "Bracing", "Chilly", "Cool", "Mild",
12        "Warm", "Balmy", "Hot", "Sweltering", "Scorching"
13    };
14
15    private readonly ILogger<WeatherForecastController> _logger;
16
17    public WeatherForecastController(ILogger<WeatherForecastController> logger)
18    {
19        _logger = logger;
20    }
21
22    [HttpGet]
23    public IEnumerable<WeatherForecast> Get()
24    {
25        _logger.LogInformation("Getting weather forecast");
26
27        return Enumerable.Range(1, 5).Select(index => new WeatherForecast
28        {
29            Date = DateOnly.FromDateTime(DateTime.Now.AddDays(index)),
30            TemperatureC = Random.Shared.Next(-20, 55),
31            Summary = Summaries[Random.Shared.Next(Summaries.Length)]
32        })
33        .ToArray();
34    }
35}
36
37public record WeatherForecast
38{
39    public DateOnly Date { get; init; }
40    public int TemperatureC { get; init; }
41    public int TemperatureF => 32 + (int)(TemperatureC / 0.5556);
42    public string? Summary { get; init; }
43}

1// Configure Kestrel in Program.cs
2var builder = WebApplication.CreateBuilder(args);
3
4builder.WebHost.ConfigureKestrel(serverOptions =>
5{
6    serverOptions.Listen(IPAddress.Any, 5000); // HTTP
7    serverOptions.Listen(IPAddress.Any, 5001, listenOptions =>
8    {
9        listenOptions.UseHttps(); // HTTPS
10    });
11
12    // Configure limits
13    serverOptions.Limits.MaxConcurrentConnections = 100;
14    serverOptions.Limits.MaxRequestBodySize = 10 * 1024 * 1024; // 10MB
15    serverOptions.Limits.KeepAliveTimeout = TimeSpan.FromMinutes(2);
16});
17
18var app = builder.Build();
19app.Run();

1// Configure forwarded headers for reverse proxy
2builder.Services.Configure<ForwardedHeadersOptions>(options =>
3{
4    options.ForwardedHeaders =
5        ForwardedHeaders.XForwardedFor |
6        ForwardedHeaders.XForwardedProto;
7});
8
9var app = builder.Build();
10
11app.UseForwardedHeaders();
12
13// Nginx configuration example:
14# /etc/nginx/sites-available/myapp
15# server {
16#     listen 80;
17#     server_name myapp.com;
18#
19#     location / {
20#         proxy_pass http://localhost:5000;
21#         proxy_http_version 1.1;
22#         proxy_set_header Upgrade $http_upgrade;
23#         proxy_set_header Connection keep-alive;
24#         proxy_set_header Host $host;
25#         proxy_cache_bypass $http_upgrade;
26#         proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
27#         proxy_set_header X-Forwarded-Proto $scheme;
28#     }
29# }

1// appsettings.json
2{
3  "Logging": {
4    "LogLevel": {
5      "Default": "Information",
6      "Microsoft.AspNetCore": "Warning"
7    }
8  },
9  "AllowedHosts": "*",
10  "ConnectionStrings": {
11    "DefaultConnection": "Server=localhost;Database=MyDb;..."
12  }
13}
14
15// appsettings.Development.json
16{
17  "Logging": {
18    "LogLevel": {
19      "Default": "Debug",
20      "Microsoft.AspNetCore": "Information"
21    }
22  }
23}
24
25// Access configuration in code
26var connectionString = builder.Configuration
27    .GetConnectionString("DefaultConnection");
28
29// Check environment
30if (app.Environment.IsDevelopment())
31{
32    app.UseDeveloperExceptionPage();
33}
34else
35{
36    app.UseExceptionHandler("/Error");
37    app.UseHsts();
38}