Introducing the .NET Framework 4.5 RC

Introducing the .NET Framework 4.5 RC

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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).

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  • I am so frustrated with Microsoft.  You don't care about your Enterprise Developers anymore do you?

    Using Visual Studio 11 to "Target .NET 4.0" really runs .NET 4.5 on your developer machine.  

    Meaning all bug that were fixed in .NET 4.5 are hidden from you as you develop.  You don't get to find out about those until you run on an XP Machine!

    Meaning that you will not know you are relying on a "fixed" bug until you release to you XP users.  

    My Company is planning on banning .NET 4.5 (and by extension VS 11).

    See this post for more details:

  • And why would you run on an XP machine? By the time VS2012 and .NET 4.5 are released, Windows XP will only have a year or so left. You should be busy getting off Windows XP right now - if not, you're in for a lot more trouble.

  • @Asbjørn

    You clearly are not familiar with Enterprise scenarios.  (Or you are being willfully ignorant in your comment).

    I don't WANT to support Windows XP.  I HAVE to.  

    Until Microsoft stops supporting it (April of 2014), our company will use it.

    It will cost many thousands of dollars to upgrade all of our systems.  If you had the choice of spending that now or in 2 years, which would you do?  (If you know about the Time-Value of money you would choose 2 years.  And so has my company.)

  • @Asbjørn

    One additional comment on this:

    I am not alone.  

    The single most requested feature for ALL OF .NET on User Voice is to support .NET 4.5 on Windows XP.

    Think of all the cool things you would like .NET to be able to do.  The users have said that they want Windows XP support more than that.

    An not just more, but by more than DOUBLE.  The next closest request does not have even half the votes that .NET 4.5 support for Windows XP has.

    Now, User Voice has turned out to be a joke.  Microsoft has chosen to not really follow what the users want (there are some Visual Studio items with Thousands of votes that are just ignored).

    But still, despite Microsoft not caring what the users are saying, it is a strong indication that my Windows XP scenario is not so odd.

  • I would like you to please consider and read the following article...

    and then have a look at this:

    Please at least take this into consideration... I specially like the comment made by RubenP on the first article at Tuesday, June 05, 2012 9:18 PM as a answer to Allen Chen [MSFT] s comment...

  • In this confusion when and where .Net 4.5 can be used I have some simple questions:

    (excluding server OS in questions)

    If I have created a WPF program in VS2010 and targeted .Net 4.0 then I can run on the following systems: WinXP, Vista and Win7? Win8 cannot be used because 4.5 will be installed and since it is in place I cannot be sure how the program will work.

    If I create a WPF program in VS2012 and target .Net 4.5 then I can run on Win7 and Win8 because .Net 4.5 is not available on XP and Vista?

    Final question: Is this intentional by Microsoft in order to force users away from XP and Vista or to force developers/users into WinRT?

  • @MEK_DK

    You are mostly correct.

    In your first scenario, you have to make sure that your dev machine does not have .net 4.5 installed.

    It does not help to use Visual Studio 2010 once you have .net 4.5 installed.  When .net 4.5 is installed it will overwrite your .net 4.0 binaries.  From then on you are using .net 4.5 for all .net 4.* development.  

    The "Target .net 4.0" option limits some of the features you can use in an attempt to simulate a .net 4.0 experience.  But you are really running in .net 4.5.  (That means that all the bugs that are fixed in .net 4.5 are now "Hidden" on your dev machine.)

    Once that happens, you can develop in Visual Studio 2010 or Visual Studio 2012 and target .net 4.0 all you want, but it will not make a difference.  

    You will always run using .net 4.5 after it is installed.

  • Itanium processors are not supported.

    You can store more than 2 GB data in arrays.

    workstation garbage collection overhead issues is solved using Server GC

    You set Timeout for Regular expressions.

    In Windows 8, it uses Unicode 6.0.0

    <a href="">.Net Training in Chennai</a>

  • It is very Useful, I did download .NET Framework 4.5 RC


  • Looking for certified trainers to provide trainings to our employees in .NET 4.5- updates; Developing apps for sharepoint, SQL server- hands on.. and more.

    We are located in Horsham, PA. If interested please contact the HR Department.


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