.NET Core: A Beginner's Guide to the Fundamentals Part 2

.NET Core is a versatile and powerful framework that has taken the world of software development by storm. In our comprehensive beginner's guide, we'll unravel the fundamentals of .NET Core, providing you with a solid foundation to kickstart your journey in this dynamic technology. From understanding its architecture to exploring the key components and concepts, this blog will equip you with the essential knowledge you need to embark on your .NET Core adventure. Join us as we demystify this popular framework and set you on the path to becoming a .NET Core pro.

Note. Before delving into this article, I recommend you read the previous part of this article for a better understanding. Part 1 - .NET Core: A Beginner's Guide to the Fundamentals.

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.NET SDK

We would use the .NET SDK to develop applications. This SDK includes everything you need to get started with .NET Core development, from creating new projects to deploying your applications.

Visual Studio and Visual Studio Code are popular Integrated Development Environments (IDEs) that seamlessly integrate with the .NET SDK, making it easier for developers to write, test, and debug their code. Both IDEs offer features like code completion, debugging tools, and project management capabilities to enhance the development experience.

By using the .NET SDK in conjunction with Visual Studio or Visual Studio Code, developers can efficiently create a wide range of applications, from web and desktop applications to cloud services and more. These tools empower developers to bring their ideas to life and streamline the development process, ultimately leading to more robust and scalable software solutions.

.NET Core Runtime

The ASP.NET Core Runtime is a component of the ASP.NET Core framework that's responsible for executing and running ASP.NET Core applications. It's a lightweight and essential part of the framework that provides the necessary environment and libraries to host and run web applications built using ASP.NET Core.

In a nutshell, the ASP.NET Core Runtime is like the engine that powers ASP.NET Core web applications. It handles tasks such as processing HTTP requests, managing routing, and interacting with the web server. It's crucial for deploying and hosting ASP.NET Core applications on a web server, making them accessible to users over the internet.

.NET Core Projects

Please check the latest .NET documentation for any updates or additional project types.

1. Console Application: Used for building command-line tools and utilities. These applications run in a console window and are ideal for automation scripts.
2. Class Library: A library project that contains reusable classes, methods, and components to be used in other .NET projects.
3. ASP.NET Core Web Application
   • MVC: Used for building web applications following the Model-View-Controller (MVC) architectural pattern.
   • API: Used for creating RESTful APIs.
   • Razor Pages: A simplified web application model for building page-based web applications.
4. Blazor Web Application: Allows you to build web applications using Blazor, which enables C# code to run directly in the browser.
5. SignalR Hub: Used for building real-time, bi-directional communication between clients and the server.
6. Worker Service: Designed for background services or long-running processes that do not require user interaction, often used for tasks like batch processing or data synchronization.
7. Azure Functions: A serverless compute service that lets you run event-triggered code without having to manage infrastructure.
8. Xamarin.Forms App (Mobile): Used for cross-platform mobile app development, where you can write a single codebase for iOS, Android, and Windows using Xamarin.
9. Windows Forms App (Desktop): Enables the creation of traditional Windows desktop applications with a graphical user interface.
10. WPF App (Desktop): Allows you to build Windows Presentation Foundation (WPF) applications, which are used for creating rich desktop applications.
11. Blazor Component Library: A project type for building reusable Blazor components that can be shared across multiple Blazor applications.
12. Entity Framework Core Project: A project used for data access and database interactions. It can be used with ASP.NET Core applications to manage data models.
13. NUnit, xUnit, or MSTest Projects: These are used for creating unit tests to ensure the correctness and reliability of your code.
14. Docker Support: Some project templates come with Docker support, allowing you to containerize your application for easier deployment and scalability.

Please note that .NET and its project templates may have evolved further since my last update. I recommend visiting the official .NET documentation or using the latest version of Visual Studio to explore the available project templates and their capabilities.

Exploring Dependency Injection

Understanding and using the built-in dependency injection system in .NET Core is a crucial aspect of modern application development. Dependency injection is a design pattern that helps manage object dependencies and promotes loose coupling between components, making your code more maintainable and testable. Here's how to understand and use the built-in dependency injection system in .NET Core:

1. Add the Required NuGet Packages: Ensure that you have the necessary NuGet packages installed. In .NET Core, the primary package is Microsoft.Extensions.DependencyInjection. You can add this package to your project using the package manager console or Visual Studio's NuGet Package Manager.
2. Service Registration: Dependency injection in .NET Core revolves around registering and resolving services. Services are objects that provide certain functionality to your application. You need to register your services in the application's startup code, typically in the Startup.cs file.

Understanding and using the built-in dependency injection system in .NET Core is a crucial aspect of modern application development. Dependency injection is a design pattern that helps manage object dependencies and promotes loose coupling between components, making your code more maintainable and testable. Here's how to understand and use the built-in dependency injection system in .NET Core:

1. Add the Required NuGet Packages: Ensure that you have the necessary NuGet packages installed. In .NET Core, the primary package is Microsoft.Extensions.DependencyInjection. You can add this package to your project using the package manager console or Visual Studio's NuGet Package Manager.
2. Service Registration: Dependency injection in .NET Core revolves around registering and resolving services. Services are objects that provide certain functionality to your application. You need to register your services in the application's startup code, typically in the Startup.cs file.

   public void ConfigureServices(IServiceCollection services)
   {
       // Register services here
       services.AddScoped<IUser, InternalUser>();
   }

   • AddScoped: The service is created once per client request (scoped to the request's lifetime).
   • AddTransient: The service is created each time it's requested.
   • AddSingleton: The service is created once for the entire application lifetime.
3. Inject Services into Your Classes: After registering your services, you can inject them into your classes that depend on these services. This is typically done through constructor injection. For example:
4. Dependency Injection Container: The.ConfigureServices method you see in the Startup class is responsible for building and configuring the dependency injection container. This container manages the lifetime and creation of registered services.
5. Using the Services: You can now use the injected services within your classes. For example, in a controller, you can invoke methods on the injected service,

   public async Task<Result> GetUsers()
   {
       var result = await _user.GetAllAsync();
       ....
   }
   

6. Scopes and Lifetime Management: Understand the different lifetimes (Scoped, Transient, and Singleton) and choose the appropriate one for your services. This ensures that services behave as expected and are created and disposed of correctly.
7. Testing and Mocking: One of the key benefits of dependency injection is that it simplifies unit testing. You can easily replace actual services with mock objects in your tests, allowing you to isolate and test your code's behavior.
8. Advanced Usage: .NET Core's dependency injection system also supports more advanced scenarios, like named instances, options configuration, and custom lifetimes.

The built-in dependency injection system in .NET Core simplifies managing object dependencies, promotes better code organization, and facilitates unit testing. It's a fundamental concept for building robust and maintainable applications in the .NET ecosystem.

Scopes and Lifetime Management

In .NET Core's built-in dependency injection (DI) system, the concept of "scopes and lifetime management" refers to how long instances of registered services are kept alive and how they are shared within an application. Understanding the different lifetimes available for services is essential for managing resources, performance, and the correct behavior of your application. Here are the details of the three main lifetimes available:

1. Transient
   • Transient services are created every time they are requested.
   • A new instance of a transient service is created for each request or injection.
   • They have the shortest lifespan, suitable for stateless and lightweight services.

     services.AddTransient<IService, Service>();

2. Scoped
   • Scoped services are created once per client request (HTTP request in the case of web applications).
   • Within the same HTTP request, all injections of a scoped service share the same instance.
   • This is useful for maintaining the state during a single request, such as a database context.

     services.AddScoped<IService, Service>();

3. Singleton
   • Singleton services are created once for the entire application lifetime.
   • All injections of a singleton service share the same instance.
   • They are suitable for stateful services that should be shared across the entire application.

     services.AddSingleton<ILogService, LogService>();

You register services with their respective lifetimes in the ConfigureServices method of the Startup class, as shown in the examples above.

Conclusion

It's important to choose the appropriate lifetime for your services, as this impacts the behavior and performance of your application:

• Transient: Use for lightweight, stateless services that don't maintain any internal state. Each usage results in a new instance.
• Scoped: Ideal for services that should share data and state within a single client request. Commonly used for database contexts and unit-of-work patterns.
• Singleton: Suitable for services that maintain a shared state across the entire application. Be cautious with mutable states, as changes may affect other parts of your application.

In the upcoming blog, we'll explore running a sample application and uncovering the hidden treasures within .NET Core.