MODULE 1

✅ Module 1: .NET Core & ASP.NET

1.1 What is .NET Core?

• Definition:
  .NET Core is a cross-platform, open-source framework developed by Microsoft for building modern, scalable, high-performance web, desktop, cloud, and mobile applications.

• Works on Windows, Linux, macOS.

• Provides support for REST APIs, MVC applications, microservices, and cloud-native apps.

1.2 Difference: .NET Core vs .NET Framework

Feature	.NET Framework	.NET Core
Platform	Windows only	Cross-platform
Performance	Comparatively slower	High performance, optimized
Deployment	Installed in Windows GAC	Can be packaged with application (self-contained)
Open Source	Partially	Fully open source
Future	Legacy support	Actively developed

👉 For interviews, always mention: “.NET Core is the future because it supports microservices, Docker, and cloud deployment.”

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1.3 Middleware in .NET Core

• Definition: Software components arranged in a pipeline to handle requests & responses.

• Every request passes through the pipeline → each middleware can process, modify, or pass the request.

• Common middleware:

  • UseRouting() → enables routing.

  • UseAuthentication() → adds authentication.

  • UseAuthorization() → checks access control.

  • UseEndpoints() → maps controller endpoints.

📌 Example:

public void Configure(IApplicationBuilder app)
{
    app.UseRouting();
    app.UseAuthentication();
    app.UseAuthorization();

    app.UseEndpoints(endpoints =>
    {
        endpoints.MapControllers();
    });
}

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1.4 Dependency Injection (DI)

• Definition: Technique to achieve loose coupling between classes.

• .NET Core has built-in DI container.

• Example:

// Service interface
public interface IMessageService { string SendMessage(); }

// Service implementation
public class EmailService : IMessageService
{
    public string SendMessage() => "Email sent!";
}

// Startup.cs
public void ConfigureServices(IServiceCollection services)
{
    services.AddScoped();
}

// Controller
public class HomeController : Controller
{
    private readonly IMessageService _messageService;
    public HomeController(IMessageService messageService) => _messageService = messageService;

    public IActionResult Index() => Content(_messageService.SendMessage());
}

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1.5 Routing

• Definition: Process of mapping incoming requests (URLs) to controllers/actions.

• Types:

  1. Conventional Routing
     Example: routes.MapRoute("default", "{controller=Home}/{action=Index}/{id?}");

  2. Attribute Routing
     Example:

     
     [Route("api/[controller]")]
     public class StudentController : Controller
     {
         [HttpGet("{id}")]
         public IActionResult Get(int id) => Ok(id);
     }
     

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1.6 Startup.cs

• Contains application configuration.

• Two main methods:

  • ConfigureServices() → register services, DI, DB context.

  • Configure() → setup middleware pipeline.

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📌 Summary for Module 1:
You should be able to explain .NET Core advantages, write a simple API using controller + routing, and describe middleware & DI flow.

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