.NET Core Migration Strategy Guide

Why Migrate to .NET Core?

With .NET Framework reaching end-of-life support, organizations are actively migrating to .NET Core/.NET 6+ for better performance, cross-platform support, and long-term viability.

Migration Assessment Strategy

Before starting migration, conduct a thorough assessment of your current application:

Application Analysis

# Use .NET Portability Analyzer
dotnet tool install -g Microsoft.DotNet.ApiPortability.GlobalTool
ApiPort analyze -f "C:\YourApp\bin" -r Excel

# Create new .NET 6 project
dotnet new web -n YourApp.Core
cd YourApp.Core

# Add necessary packages
dotnet add package Microsoft.EntityFrameworkCore.SqlServer
dotnet add package Microsoft.AspNetCore.Authentication.JwtBearer

{
  "ConnectionStrings": {
    "DefaultConnection": "Server=.;Database=YourApp;Trusted_Connection=true"
  },
  "Jwt": {
    "Key": "YourSecretKey",
    "Issuer": "YourApp",
    "Audience": "YourApp"
  },
  "Logging": {
    "LogLevel": {
      "Default": "Information",
      "Microsoft.AspNetCore": "Warning"
    }
  }
}

// Old .NET Framework Controller
public class ProductController : Controller
{
    private readonly IProductService _productService;
    
    public ProductController()
    {
        _productService = new ProductService();
    }
}

// New .NET Core Controller
[ApiController]
[Route("api/[controller]")]
public class ProductController : ControllerBase
{
    private readonly IProductService _productService;
    
    public ProductController(IProductService productService)
    {
        _productService = productService;
    }
}

Common Migration Patterns

Here are the most common patterns we use for successful migrations:

Entity Framework Migration

// Program.cs - .NET 6 style
var builder = WebApplication.CreateBuilder(args);

// Add services
builder.Services.AddDbContext<ApplicationDbContext>(options =>
    options.UseSqlServer(builder.Configuration.GetConnectionString("DefaultConnection")));

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

var app = builder.Build();

// Configure pipeline
if (app.Environment.IsDevelopment())
{
    app.UseDeveloperExceptionPage();
}

app.UseHttpsRedirection();
app.UseAuthentication();
app.UseAuthorization();

app.MapControllers();
app.Run();

Authentication Migration

// JWT Authentication setup
builder.Services.AddAuthentication(JwtBearerDefaults.AuthenticationScheme)
    .AddJwtBearer(options =>
    {
        options.TokenValidationParameters = new TokenValidationParameters
        {
            ValidateIssuer = true,
            ValidateAudience = true,
            ValidateLifetime = true,
            ValidateIssuerSigningKey = true,
            ValidIssuer = builder.Configuration["Jwt:Issuer"],
            ValidAudience = builder.Configuration["Jwt:Audience"],
            IssuerSigningKey = new SymmetricSecurityKey(
                Encoding.UTF8.GetBytes(builder.Configuration["Jwt:Key"]))
        };
    });