Introducing the .NET Framework 4.5 RC

Today, we are announcing the .NET Framework 4.5 RC. We are also announcing Visual Studio 2012 RC, as you can read on Jason Zander’s and Soma’s blog. Please visit the Visual Studio 2012 RC downloads page to install both products.

We have made many improvements since we released the .NET Framework 4.5 Beta in February.  Let’s talk about the changes at a high level:

  • Windows Metro style app performance: We significantly improved the performance of apps that you build using the .NET APIs for Metro style apps across many dimensions since Beta. In particular, we reduced startup time substantially, with improvements observed in the 10% range. We updated the garbage collector to aggressively reclaim memory upon app suspension, which benefits both the end-user experience and the app (avoids termination). We also improved file I/O performance when using the .NET Framework stream adapters by adding automatic buffering of the underlying Windows Runtime streams.    Separately, we improved the algorithm by which Metro style apps are optimized for performance, via automatic native image generation.
  • Metro style app programming experience for C# and Visual Basic: We made a large number of improvements and also made adjustments to align the .NET Framework with changes in the Windows Runtime API. Examples include better support for IRandomAccessStream from the .NET Framework. We also introduced .NET Framework performance testing in the Windows App Certification Kit.
  • ASP.NET: Many updates, including: better support for async, cancellation, and threading; support for Entity Framework enumerations and spatial data types in Dynamic Data; support for unit testing; support for Entity Framework 5.0 RC; and improvements for extending the Web Forms compilation system. We also updated the ASP.NET Web API to use Json.Net for JSON formatting, added support for creating custom help pages, improved integration with IoC containers, and provided a monitoring and tracing infrastructure.
  • WCF: Many improvements, including: better performance, reliability and scale with WebSockets; support for client-side validation of the server SSL certificate using WCF’s custom X509 certificate validator on a per-request basis , and; support for adding simple WCF service references inside a managed Windows metadata (.WinMD) file, allowing JavaScript apps to call WCF services via the Windows Runtime.
  • Broad range of product improvements: Many areas of the product benefited from small but important improvements addressing app reliability, compatibility, and performance. We also responded to over 200 Connect feedback bugs and fixed many of the reported issues.

Take a look at What’s New in the .NET Framework 4.5 RC to learn more about the new features. We also made significant updates to our performance guidance, in the Performance best practices for C# and Visual Basic topic. Also see Scott Hanselman’s blog for more information on ASP.NET. Once again, please do download the .NET Framework 4.5 RC release.

As always, we would like to hear from you. Please don’t hesitate to post a comment on the blog or at one of the forums that we monitor: Connect (report bugs), UserVoice (request features), and MSDN Forums (ask for help).