Making an application portable - registering DLLs, and DLLs in system32

Question

I want to make an application portable (on Windows XP), so that it can run directly from a CD. The application requires some DLLs and OCXs to be registered, and some of these need to be in system32 when registered (for some reason).

What are the consequences of registering a lot of DLLs with regsvr32 in a wrapper program/script around the application? Could this mess up a system? And what happens when the files are removed (since they are on a removable media)?. I guess I could unregister them again when the portable application is stopped, but what if one of them is a common DLL which is also used by other applications? Would unregistering it break those other applications?

I assume that copying files randomly to system32 when staring a portable application is a bad idea. Why would an application require that some DLLs and OCXs are in the System32-folder? Is there a way to work around it? Is the only way to make the wrapper program/script make sure that none of the files already exist before copying, and remove them after running the application?

Has the way these things work changed in Windows Vista and 7?

The application I want to make portable is the demo version of the (Norwegian) genealogy application Embla Familie og Slekt (Norwegian website, translated by Google). My grandfather, who did a lot of genealogy work, passed away recently, so I would like to distribute his work to my relatives. It would be great if all they had to do was insert a CD, and the software would pop up. Installing it and setting it up to use my grandfather's data is a bit complicated for a novice computer user. (I have tried to contact the authors without success, but I will try again if I get it to work, to make sure that distributing the demo is legal)

Thank you, and please forgive my ignorance - I usually don't run Windows. :)

Answer 1

I don't know why the DLL's would have to be in System32; they shouldn't have to be, it is bad practice to but application DLL's in the systems' directory.

Yes, DLL's and OCX's that expose COM object (e.g. those that need to be registered), do need to be registered and listed in the registry. However, with Windows XP and later there is registration free COM. The short explanation is that for each .DLL and .EXE you create a filename.ext.manifest file that lists all the components that it exports and uses. Unfortunately reality is more complex. See this article for a description. It is theoretically possible to come up with the information you need for the manifest files, but you will need a good understanding of COM.

Answer 2

Many years ago, I understood that when Windows needed a dll file that wasn't registered, it automatically looked in the directory of the exe file. In such a world, making the application portable is very easy.

I have no idea if I am remembering this right (or even more or less right) or whether or not it is still the case, but copying all the files to a USB stick and putting it in another computer would be a fairly quick and easy check.