The .NET 9 Release Candidate 1, released on September 12, 2024, introduces several significant updates across its core components, libraries, and frameworks. Here are the key changes:

Libraries

  • WebSocket Enhancements: New APIs for configuring keep-alive pings and timeouts have been added, allowing developers to manage WebSocket connections more effectively.
  • Compression Options: Introduction ofZLibCompressionOptions andBrotliCompressionOptions, providing more granular control over compression strategies compared to the previousCompressionLevel option.
  • TAR Archive Management: A new public property,DataOffset, inSystem.Formats.Tar.TarEntry allows developers to access the position of data within TAR archives, facilitating better handling of large files.
  • HttpClientFactory Logging: By default,HttpClientFactory will no longer log header values to enhance security; developers can selectively log specific headers using theRedactLoggedHeaders method.
  • Workload Management: The commanddotnet workload history has been introduced to track the history of workload installations and modifications within a .NET SDK installation.

ASP.NET Core

  • SignalR Improvements: Enhancements include better distributed tracing and a keep-alive timeout feature for WebSockets.
  • Dependency Injection: Support for Keyed Dependency Injection (DI) services in middleware has been added, improving flexibility in service management.
  • HTTPS Certificate Trusting: The ASP.NET Core HTTPS development certificate can now be trusted on Linux systems.

.NET MAUI

  • Text Alignment Feature: A new option,HorizontalTextAlignment.Justify, has been introduced for better text alignment in labels.
  • HybridWebView Updates: Improvements in the HybridWebView component include guidance for invoking JavaScript from C#.

Diagnostics and Monitoring

  • Out-of-proc Meter Wildcard Listening: A new feature that allows wildcard support in both in-process and out-of-process scenarios, enhancing monitoring capabilities.

These updates aim to improve performance, security, and developer experience as Microsoft prepares for the official release of .NET 9 later this year