What is .NET 9: A Developer's Perspective

.NET Evolution, Microsoft's open-source platform, has been a cornerstone of the software development industry, enabling developers to create diverse applications across multiple platforms. .NET has evolved, and at the end of 2024, the company launched .NET 9, introducing new features and improvements to meet the needs of developers in a constantly changing digital world.

The platform includes updates for ASP.NET Core, Blazor, C#, F#, .NET MAUI, and development tools such as Visual Studio and Visual Studio Code. Additionally, it focuses on the generative AI ecosystem, providing new abstractions to integrate AI model services into .NET applications.

Regarding web development, .NET 9 includes features such as optimized static file handling in ASP.NET Core, hybrid caching, and the new interactive renderer in Blazor. But let's take a more detailed look at all its new additions.

What are the new .NET 9 features?

.NET 9 emphasizes cloud-native applications and performance. It is designed to make development faster, easier, and more reliable. It aims to improve efficiency and security while introducing new language features that simplify development. The goal? To enable development teams to perform their tasks more effectively.

1. Ever-increasing performance 

As with every major release from Microsoft, .NET 9 promises to be the highest-performing version to date. This has been achieved through more than 1,000 changes implemented in the runtime, workloads, and programming languages.

One of the most significant changes is in the Server Garbage Collector (Server GC). From this version onwards, it will intelligently adapt to the application's memory needs. This change has a major impact in environments with many processor cores where application memory is limited or fluctuates significantly.

Moreover, .NET 9 leverages vectorization to harness the power of next-generation processors, significantly accelerating runtime on such hardware. Additionally, LINQ, a fundamental component of .NET, has also been optimized, resulting in a speed increase of up to 10 times in some methods. Overall, this deep optimization translates into faster, more efficient applications with lower resource consumption.

2. New features in ASP.NET Core and Blazor 

.NET 9 brings a series of improvements to ASP.NET Core and related technologies, focusing on efficiency, security, and a better development experience.

A key improvement in this version is the handling of static files, which are essential in almost all web applications. ASP.NET Core now optimizes these files during compilation and publishing.

On the other hand, Blazor, the framework for building interactive web interfaces with C#, has also been enhanced in .NET 9. It can now detect the component's rendering mode at runtime using the new RendererInfo API and adjust rendering accordingly. This allows interactive elements to be disabled or hidden during pre-rendering and enables them once the component is interactive.

3. Cross-platform development enhancements: .NET MAUI 

9 .NET MAUI is Microsoft's tool for building cross-platform applications with .NET, both for mobile and desktop devices. An important aspect of this version is the addition of a new MAUI project template that includes 14 free, open-source Syncfusion controls, along with other popular community libraries. This template offers better access to databases, navigation, view updates, and other common application development patterns.

4. What's new in C# 12 

.NET 9 ships with the latest versions of C#, featuring new capabilities that make code more readable, less repetitive, and optimized for performance. Key features of C# 12 include:

• Primary constructors: This feature simplifies class construction by allowing properties to be declared directly within the constructor.

• List patterns: These patterns match list types, making operations on arrays and collections much easier.

• Parameter null-checking: Built-in null value checks for parameters to prevent common runtime errors.

• Inline functions: This allows developers to declare inline functions, making code more efficient and concise.

5. .NET Aspire: The evolution of app development

.NET Aspire is a set of tools, templates, and packages designed to facilitate the development of robust, production-ready applications with observability capabilities. In other words, it provides developers with essential elements to build high-quality applications that can be monitored and managed effectively.

In .NET Aspire 9, significant improvements have been introduced based on developer community requests, including:

• Resource management from the control panel: Now it is possible to start and stop resources directly from the control panel, simplifying application management.

• Maintaining active containers: Containers can remain active between debugging sessions, streamlining the development workflow.

• New APIs: New APIs, such as WaitFor, have been added to better manage resource initialization.

• Integrations: New integrations have been implemented for OpenAI, Ollama, Milvus, and other popular tools, expanding .NET Aspire's functionality.

• Simplified implementation: The process of acquiring and integrating .NET Aspire into applications has been simplified.

• Improvements in Azure Container Apps: Deployment scenarios with Azure Container Apps have been enhanced.

• Support for Azure Functions: Preview support for Azure Functions with .NET Aspire has been added.

.NET 9, a step towards the future .NET 9 positions itself as a version that consolidates .NET's standing as a robust, versatile, and high-performance platform for modern application development. This release goes beyond incremental improvements, introducing significant changes in key areas that enhance developer productivity and open new possibilities in fields such as AI and web development.

In summary, .NET 9 consolidates the strengths of .NET, pushes it toward the future, and reinforces it as one of the most capable platforms to tackle the challenges of modern software development.