.net – Backwards Compatibility of .NET Framework 4

.net-4.0netwpf

We have an WPF Application build on .net framework 3.5.

Some testers find if they uninstall .net framework 3.5, but install .net framework 4.0, our APP fails to launch itself.

Dose this mean that .net framework 4.0 does not include all 3.5 libs, and users have to install .net 3.5 even though they have 4.0?

I see here are some migration issues listed by Microsoft
http://msdn.microsoft.com/en-us/library/ee941656.aspx#windows_presentation_foundation_wpf

Are they all breaking changes so that the backward compatibility is ruined?

Thanks

Best Answer

.Net 3.5/2.0 Applications do not automatically run on the .Net 4.0 runtime. You have to specify explicitly for your application that it should run on .Net 4.0 in your App.config by adding:

<configuration>
  <startup>
    <supportedRuntime version="v4.0" /> 
  </startup>
</configuration>

In case you have third party components you also have to mark them as being ready for 4.0:

<configuration>
   ...
   <runtime>
      ...
      <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
         ...
         <dependentAssembly>
            <assemblyIdentity name="AssemblyName" publicKeyToken="31bf3856ad364e35"/>
            <bindingRedirect oldVersion="3.5.0.0-3.5.0.0" newVersion="4.0.0.0"/>
         </dependentAssembly>
         ...
      </assemblyBinding>
      ...
   </runtime>
   ...
</configuration>

Related Solutions

.net – Difference between decimal, float and double in .NET

float and double are floating binary point types. In other words, they represent a number like this:

10001.10010110011

The binary number and the location of the binary point are both encoded within the value.

decimal is a floating decimal point type. In other words, they represent a number like this:

12345.65789

Again, the number and the location of the decimal point are both encoded within the value – that's what makes decimal still a floating point type instead of a fixed point type.

The important thing to note is that humans are used to representing non-integers in a decimal form, and expect exact results in decimal representations; not all decimal numbers are exactly representable in binary floating point – 0.1, for example – so if you use a binary floating point value you'll actually get an approximation to 0.1. You'll still get approximations when using a floating decimal point as well – the result of dividing 1 by 3 can't be exactly represented, for example.

As for what to use when:

For values which are "naturally exact decimals" it's good to use decimal. This is usually suitable for any concepts invented by humans: financial values are the most obvious example, but there are others too. Consider the score given to divers or ice skaters, for example.
For values which are more artefacts of nature which can't really be measured exactly anyway, float/double are more appropriate. For example, scientific data would usually be represented in this form. Here, the original values won't be "decimally accurate" to start with, so it's not important for the expected results to maintain the "decimal accuracy". Floating binary point types are much faster to work with than decimals.

.net – Differences between Microsoft .NET 4.0 full Framework and Client Profile

What's new in .NET Framework 4 Client Profile RTM explains many of the differences:

When to use NET4 Client Profile and when to use NET4 Full Framework?
NET4 Client Profile:
Always target NET4 Client Profile for all your client desktop applications (including Windows Forms and WPF apps).

NET4 Full framework:
Target NET4 Full only if the features or assemblies that your app need are not included in the Client Profile. This includes:

If you are building Server apps. Such as:
o ASP.Net apps
o Server-side ASMX based web services

If you use legacy client scenarios. Such as:
o Use System.Data.OracleClient.dll which is deprecated in NET4 and not included in the Client Profile.
o Use legacy Windows Workflow Foundation 3.0 or 3.5 (WF3.0 , WF3.5)

If you targeting developer scenarios and need tool such as MSBuild or need access to design assemblies such as System.Design.dll

However, as stated on MSDN, this is not relevant for >=4.5:

Starting with the .NET Framework 4.5, the Client Profile has been discontinued and only the full redistributable package is available. Optimizations provided by the .NET Framework 4.5, such as smaller download size and faster deployment, have eliminated the need for a separate deployment package. The single redistributable streamlines the installation process and simplifies your app's deployment options.

Best Answer

Related Solutions

.net – Difference between decimal, float and double in .NET

.net – Differences between Microsoft .NET 4.0 full Framework and Client Profile

Related Topic