Updating a DLL in the GAC

Question

I have an API DLL that several third party applications reference.

Some of these applications want things two ways in terms of updates. 1) I want the latest stuff 2) D

Answer 1

How difficult is it to update the GAC DLL so that the references to it don't break but the binary contents differs?

You can't do it directly. You can only put signed DLLs into the GAC. When you build your app against a signed DLL, the compiler takes a hash of the contents of the DLL and puts it in the app. When the .NET runtime loads the app, it checks this hash against the real copy of the DLL. If this DLL doesn't match the one you built with, .NET throws an exception.

The way to work around this is to:

1. Put in place a version numbering scheme for your GAC DLL. This can be as straightforward as always incrementing the version number when you do a build.
2. In your app.config, add a element

In effect a binding redirect says, "if you're looking for a DLL with version numbers in the range 1.x to 1.y, look at version 1.z instead".

Edit: There are ways round the .NET strong name integrity check, but I recommend designing your application around the standard strong name mechanism before trying to circumvent it.