Overview

.NET Core is a cross-platform, open-source framework developed by Microsoft to allow application development for Windows, Linux, and macOS. Its inception marked a significant shift from the traditional .NET Framework by enhancing flexibility, modularity, and performance. Understanding the differences and benefits of .NET Core compared to the .NET Framework is crucial for developers to make informed choices about the appropriate technology stack for their applications.

Key Concepts

1. Cross-Platform Support: Unlike the .NET Framework, which is Windows-only, .NET Core supports development and deployment across multiple operating systems.
2. Performance: .NET Core is optimized for modern workloads and cloud environments, offering significant performance improvements over the .NET Framework.
3. Modularity and Deployment: .NET Core features a modular framework and enables self-contained deployments, reducing application conflicts and simplifying the deployment process.

Common Interview Questions

Basic Level

1. What is the main difference between .NET Core and the .NET Framework?
2. How do you create a simple web API in .NET Core?

Intermediate Level

3. Explain the benefits of .NET Core's modularity and how it affects application development.

Advanced Level

4. Discuss performance optimizations in .NET Core for high-throughput applications.

Detailed Answers

1. What is the main difference between .NET Core and the .NET Framework?

Answer: The main difference lies in their platform support and application model. .NET Framework is a mature, Windows-only framework designed for building desktop, web, and mobile applications. In contrast, .NET Core is a cross-platform, open-source framework aimed at building cloud-based, server-side applications that can run on Windows, Linux, and macOS.

Key Points:
- Cross-Platform: .NET Core supports various operating systems.
- Open Source: .NET Core is open-source, allowing community contributions.
- Performance: .NET Core provides enhanced performance and efficiency.

Example:

// Creating a simple .NET Core console application
using System;

namespace HelloWorld
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("Hello World from .NET Core!");
        }
    }
}

2. How do you create a simple web API in .NET Core?

Answer: Creating a web API in .NET Core involves setting up a project, defining a model, creating a controller, and configuring routing. .NET Core's CLI tools simplify this process.

Key Points:
- Project Setup: Initialize a new web API project using CLI tools.
- Model Definition: Create data models to represent resources.
- Controller Implementation: Develop controllers to handle HTTP requests.
- Routing: Configure endpoint routing to map requests to actions.

Example:

// Command to create a new Web API project
// dotnet new webapi -n SimpleApi

using Microsoft.AspNetCore.Mvc;

namespace SimpleApi.Controllers
{
    [Route("api/[controller]")]
    [ApiController]
    public class GreetingsController : ControllerBase
    {
        [HttpGet]
        public ActionResult<string> Get()
        {
            return "Hello from .NET Core Web API!";
        }
    }
}

3. Explain the benefits of .NET Core's modularity and how it affects application development.

Answer: .NET Core's modularity means developers can include only the necessary packages and libraries for their application, reducing the overall footprint and improving performance. This modularity facilitates easier updates, security patches, and sharing across different applications, leading to more maintainable and scalable application development.

Key Points:
- Reduced Deployment Size: Applications only deploy with needed components.
- Improved Performance: Less overhead and faster startup times.
- Simplified Maintenance: Easier to update and manage dependencies.

Example:

// Example showing how to add a specific NuGet package
// dotnet add package Microsoft.EntityFrameworkCore.SqlServer

// This command adds only the SQL Server provider for Entity Framework Core,
// demonstrating modularity by including only what is necessary.

4. Discuss performance optimizations in .NET Core for high-throughput applications.

Answer: .NET Core introduces several performance optimizations for high-throughput applications, including improved asynchronous programming patterns, Span for more efficient memory management, and enhanced JIT compilation. Additionally, Kestrel, .NET Core's lightweight web server, offers significant performance benefits for web applications.

Key Points:
- Asynchronous Programming: Minimizes thread blocking and improves scalability.
- Span: Provides a type-safe way to represent contiguous regions of memory.
- JIT Compilation Enhancements: Optimizes runtime execution speed.

Example:

using System;
using System.Threading.Tasks;

public class PerformanceOptimizationExample
{
    public async Task ProcessDataAsync(byte[] data)
    {
        // Asynchronous processing example
        await Task.Run(() =>
        {
            // Processing data asynchronously to improve scalability
            Console.WriteLine("Processing data...");
        });
    }

    public void UseSpan(byte[] data)
    {
        // Using Span<T> for memory-efficient data access
        Span<byte> dataSpan = new Span<byte>(data);
        // Perform operations with dataSpan
    }
}