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Which CLR will an application that uses DLLs that have been compiled for different versions of .net use?

Answer 1

+1 A:

No. If you target the 3.5 version framework, it ill not magically use the 2.0 if 3.5 is not present.

But you can use assemblybinding bindingredirect in the app.exe.config to specify a replacement version:

<configuration>

   ....

  <runtime>
    <assemblybinding xmlns="urn:schemas-microsoft-com:asm.v1">
      <dependentassembly>
        <assemblyidentity name="System" culture="neutral" publickeytoken="969db8053d3322ac" />
        <bindingredirect newVersion="2.0.0.0" oldVersion="1.0.5000.0" />
      </dependentassembly>
      <dependentassembly>
        <assemblyidentity name="System.Windows.Forms" culture="neutral" publickeytoken="969db8053d3322ac" />
        <bindingredirect newVersion="2.0.0.0" oldVersion="1.0.5000.0" />
      </dependentassembly>      
    </assemblybinding>
  </runtime>

</configuration>

See Redirecting Assembly Versions

Mitch Wheat 2010-02-21 09:49:03

Mitch. Your answer is not clear. Are you saying that the DLL WONT use the parents runtime? If not, are 2 CLRs loaded?

Bobby Alexander 2010-02-21 10:27:05

@Bobby Alexander: could you clarify your question please.

Mitch Wheat 2010-02-21 10:33:33

Mitch, What I wanted to know was this: If an exe is built for framework 3.5 but the DLLs it uses (references) are built on .net 1.1, will the dlls automatically run on 2.0 CLR (same as the parent)?

Bobby Alexander 2010-02-22 05:51:37

Answer 2

A:

If your application uses framework 3.5 (which is really CLR 2) and it loads dlls compiled for CLR 1.0 or CLR 1.1 then these dlls will automatically use CLR 2. You can not go the other way - ie. you can not load a CLR 2 dll into a CLR 1 process without some hurt.

In CLR 4 these rules change a bit as you can now have multiple CLR instancs in a given process, this is however only relevant if you instantiate objects through COM, not if you load through normal reflection.

S.Skov 2010-02-21 12:25:07

Answer 3

+1 A:

It is the EXE file that decides what .NET runtime version the process will use. Any assemblies compiled for earlier versions of .NET will have to use "process version". This usually works as .NET has had very few breaking changes.

A .NET 3.5 application using a .NET 1.1 DLL will run that DLL on the CLR 2.0 (.NET 2.0, 3.0 and 3.5 all uses the same CLR 2.0 version).

.NET 4 has a new CLR and one of the new features of .NET 4 is in-process side by side CLR hosting that allows multipe versions of.NET in the same process and that may change the answer..

Arve 2010-02-21 12:37:34

Arve, which framework dlls will they use? I mean, if the 1.1 dlls are running on 2.0 CLR, will it use the parents framework dlls (3.5) or the one it is built on (1.1)?

Bobby Alexander 2010-02-22 05:53:26

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Which CLR will an application that uses DLLs that have been compiled for different versions of .net use?

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