ASP.NET Core MVC Architecture - In-Depth Notes

Overview

ASP.NET Core MVC follows the Model-View-Controller architectural pattern, separating application logic into three interconnected components. This promotes separation of concerns, testability, and maintainability.

1. Program.cs - Application Entry Point

WebApplication Builder Pattern

var builder = WebApplication.CreateBuilder(args);

• WebApplicationBuilder: Factory pattern for configuring services and middleware
• args: Command-line arguments passed to the application
• Creates the host, configures services, and builds the application pipeline

Service Registration & Dependency Injection

Service Container

ASP.NET Core has a built-in IoC (Inversion of Control) container for dependency injection:

// Different service lifetimes demonstrated in your code:

// SCOPED - One instance per HTTP request
builder.Services.AddScoped(typeof(ISpellChecker), typeof(EnglishSpellChecker));

// SINGLETON - One instance for application lifetime
builder.Services.AddSingleton(typeof(ISpellChecker), typeof(EnglishSpellChecker));

// TRANSIENT - New instance every time requested (not shown but available)
builder.Services.AddTransient<ISpellChecker, EnglishSpellChecker>();

Service Lifetimes Explained

1. Singleton: Created once, shared across all requests
   • Use for: Stateless services, configuration, caching
   • Memory efficient but must be thread-safe
2. Scoped: Created once per HTTP request
   • Use for: Database contexts, user-specific services
   • Default for most business services
3. Transient: Created every time requested
   • Use for: Lightweight, stateless services
   • Most memory intensive

MVC Services Registration

builder.Services.AddControllersWithViews();

Registers essential MVC services: