News
XAML Speeds Up, JSON Gets Smarter in .NET 10 Preview 7
In .NET 10 Preview 7, Microsoft has introduced two key features aimed at improving developer productivity and performance. The new XAML Source Generator for .NET MAUI generates XAML code at compile time instead of parsing it at runtime, which can reduce startup times and surface XAML errors earlier in the development process. Meanwhile, PipeReader support in System.Text.Json enables more efficient handling of large or streaming JSON payloads, helping reduce memory usage and improve throughput in scenarios such as web APIs and real-time data processing.
Also, desktop and data developers got some love after Preview 6 was devoted to "quality improvements and build performance" improvements for that tooling in a "relatively small" release.
Desktop/Data
For desktop development, Preview 7 brings dark mode rendering fixes and enhancements to Windows Forms controls including ComboBox, RichTextBox, and PropertyGrid. Windows Presentation Foundation (WPF) receives Fluent theme improvements, while Entity Framework Core adds improved translation for parameterized collections along with other small fixes. These updates focus on usability and visual consistency rather than introducing new major features.
Here's a look at features, tweaks fixes and changes to other properties, starting with that XAML source generator.
.NET MAUI
The headline feature generates compiled representations of XAML files during the build process instead of parsing them at runtime. By shifting this work to compile time, it can reduce application startup latency and catch XAML errors earlier, making the development cycle more efficient. The generated code can also be inspected, providing developers with greater transparency into how their XAML is processed.
Preview 7 also adds MediaPicker EXIF support, enabling developers to retrieve Exchangeable Image File Format metadata from images selected with the MediaPicker API. This can be useful for applications that need to handle image metadata such as orientation, timestamps, or geolocation information.
SafeArea enhancements give developers finer control over how content adapts to device notches, rounded corners, and other display cutouts, helping improve layout consistency across devices. The update also introduces support for secondary toolbar items, allowing additional commands to be displayed in application toolbars beyond the primary set of actions.
New control APIs expand customization options for developers, while some older, deprecated APIs have been removed to streamline the framework. Microsoft notes that a full list of quality improvements for .NET MAUI is available in the dotnet/maui GitHub releases.
ASP.NET Core & Blazor
PipeReader support in System.Text.Json is a key update for ASP.NET Core in Preview 7. This integration allows JSON serialization and deserialization directly from a PipeReader, improving performance and reducing memory allocations when processing large or streaming JSON payloads. It is particularly beneficial for high-throughput scenarios such as web APIs, real-time messaging, and data pipelines where minimizing overhead is critical.
Other ASP.NET Core updates include the ability to configure suppression of exception handler diagnostics, which can help developers control logging output in production environments. Authentication gains improvements for passkeys, making passwordless sign-in flows more seamless. Support for the .localhost top-level domain is now included, simplifying local development setups that rely on hostnames rather than raw IP addresses.
Blazor receives enhancements such as improved validation for classes and records, aligning with modern data annotation and model binding practices. The framework also now uses PipeReader support in System.Text.Json for its own JSON handling, further improving Blazor's performance in component serialization scenarios. Additionally, the OpenAPI.NET dependency has been upgraded to its stable release, ensuring compatibility with the latest OpenAPI tooling.
More information is detailed in the release notes.
Other Improvements
- Launch Windows processes in new process group -- Adds an option to start Windows processes in a separate process group for cleaner signal handling and termination control. Details.
- AES KeyWrap with Padding (IETF RFC 5649) -- Implements padded AES key wrap for broader standards compliance in cryptographic workflows. Details.
- ML-DSA -- Adds support for the new digital signature algorithm to keep pace with modern security requirements. Details.
- Composite ML-DSA -- Introduces composite variants of ML-DSA for additional signing flexibility. Details.
WebSocketStream -- Provides a stream abstraction over WebSockets to simplify read/write patterns in real-time apps. Details.- TLS 1.3 for macOS (client) -- Enables TLS 1.3 on macOS clients for improved security and connection performance. Details.
- Use any
RuntimeIdentifier with platform-specific tools -- Relaxes restrictions so platform-specific .NET tools can run with any RID, improving build/deploy flexibility. Details.
- Avoid cookie login redirects for known API endpoints -- Prevents cookie-based auth from redirecting API calls to HTML login pages in ASP.NET Core. Details.
- WPF bug fixes -- General reliability fixes alongside the Fluent theme work noted earlier. Details.
dnx on PATH in SDK container images -- Adds dnx to PATH by default to streamline CLI usage in containers. Details.
About the Author
David Ramel is an editor and writer at Converge 360.