Detect if an assembly is available

Question

I'm implementing an installer in Java, that is supposed to download and install an application for non-privileged users in Windows (from XP and up). The application is written in C++, and depend on the usual VC runtime-libraries (msvcm90.dll and friends). In order to save bandwidth, I want to avoid downloading the VC redistributables if they already are available for the user. I do however have a problem finding a reliable method to detect if an assembly is installed.

If the assembly is missing, I will deploy it as described here:

http://msdn.microsoft.com/en-us/library/ms235291%28VS.80%29.aspx

So the question is simply how to detect if a (any) assembly is installed on the machine. It's no requirement that this can be done from Java. I can easily write a small probe in C++ and link it statically for the task.

jgaa

Answer 1

Seems a fairly complicated trick really as depending on the setup these may already be located in several possible places. Perhaps your best bet would be testing for the existence of these DLL's using the WinAPI LoadLibrary - this should find any DLL that is shared and appropriate to the build automatically.

Even better LoadLibrary a DLL that requires them as Ben suggests.

Answer 2

If you are willing to write a small test program, then rather than writing one that looks for your dependencies, write one that has the same dependencies as your application. Try to run it. If it runs, the dependencies are in place. If it fails, the probable reason is that the dependencies are missing.