Is it possible to load an assembly targeting a different .NET runtime version in a new app domain?
- by Notre
Hello,
I've an application that is based on .NET 2 runtime. I want to add a little bit of support for .NET 4 but don't want to (in the short term), convert the whole application (which is very large) to target .NET 4.
I tried the 'obvious' approach of creating an application .config file, having this:
<startup useLegacyV2RuntimeActivationPolicy="true">
<supportedRuntime version="v4.0" />
</startup>
but I ran into some problems that I noted here.
I got the idea of creating a separate app domain. To test it, I created a WinForm project targeting .NET 2. I then created a class library targeting .NET 4. In my WinForm project, I added the following code:
AppDomainSetup setup = new AppDomainSetup();
setup.ApplicationBase = "path to .NET 4 assembly";
setup.ConfigurationFile = System.Environment.CurrentDirectory +
"\\DotNet4AppDomain.exe.config";
// Set up the Evidence
Evidence baseEvidence = AppDomain.CurrentDomain.Evidence;
Evidence evidence = new Evidence(baseEvidence);
// Create the AppDomain
AppDomain dotNet4AppDomain = AppDomain.CreateDomain("DotNet4AppDomain", evidence, setup);
try
{
Assembly doNet4Assembly = dotNet4AppDomain.Load(
new AssemblyName("MyDotNet4Assembly, Version=1.0.0.0, Culture=neutral, PublicKeyToken=66f0dac1b575e793"));
MessageBox.Show(doNet4Assembly.FullName);
}
finally
{
AppDomain.Unload(dotNet4AppDomain);
}
My DotNet4AppDomain.exe.config file looks like this:
<startup useLegacyV2RuntimeActivationPolicy="true">
<supportedRuntime version="v4.0" />
</startup>
Unfortunately, this throws the BadImageFormatException when dotNet4AppDomain.Load is executed. Am I doing something wrong in my code, or is what I'm trying to do just not going to work?
Thank you!
