在仅具有4.0框架的机器上参考2.0库运行.NET 4.0应用程序

Question

This would be a real pain to try to duplicate, so I'm hoping someone has a quick answer...

Suppose I have a .NET 4.0 application, with a reference to a .NET 2.0 library (SharpZipLib in this case). This of course works fine on a normal machine with .NET 2.0 and 4.0 installed.

If the server running this application has only .NET 4.0 and not 2.0 (or 3.0/3.5 etc.), what do I need to do to allow the .NET 2.0 library to run properly?

From what I've read, it looks like I may be able to put in a config setting for supportedRuntime , but I'm not quite understanding what exactly that does.

Will a config setting work, or would only .NET 4.0 libraries function in this environment?

(This is a hypothetical environment - I don't plan on ever having my own servers with 4.0 and not 2.0, but if someone is crazy enough to do it, I want to be able to support them).

Thanks

Answer 1

The CLR can load older assemblies in the .net 4.0 framework.

Here's a good read:

http://msdn.microsoft.com/en-us/magazine/ee819091.aspx

EDIT: updated quote from article. Particularly notice the bold

The .NET Framework 4 runtime—and all future runtimes—will be able to run in-process with one another. While we did not back-port this functionality to older runtimes (1.0 through 3.5), we did make sure that 4 and beyond will be able to run in-process with any single older runtime. In other words, you will be able to load 4, 5 and 2.0 in the same process, but you will not be able to load 1.1 and 2.0 in the same process. .NET Frameworks 2.0 through 3.5 all run on the 2.0 runtime and so have no conflicts with one another, as shown in Figure 2.

Answer 2

From http://neilblackburn.blogspot.com/2009/10/net-framework-40-backward-compatibility.html (and, transitively, http://mtaulty.com/CommunityServer/blogs/mike_taultys_blog/archive/2009/08/03/installing-net-framework-v4-0-and-running-net-2-0-3-0-3-5-3-5sp1-applications.aspx ):

Now, I knew that you can't just take a 3.5 Service Pack 1 application and run it on the V4.0 CLR. It needs a V2.0 CLR or reconfiguring with a <supportedRuntimes/> tag in order to bend the application to run on the V4.0 CLR and that bending might be something that you don't want to do.

Answer 3

From the link in bryanmac's answer ( In-Process Side-by-Side ):

This means that if an application is recompiled to run against the .NET Framework 4 runtime and still has dependent assemblies built against .NET 2.0, those dependents will load on the .NET 4 runtime as well.

That can mean, however, that there may be bugs due to being run on a different runtime.

Answer 4

如果您拥有SharpZipLib的源代码，则可以将其重建为.NET 4.0