Comparing Two "Identical" Virtual Software Archives

Here's the scenario: Customer creates a VSA for App X -- it doesn't work. You create a VSA for the same application -- it works great.

Wouldn't it be nice if you could quickly compare the two VSAs to find out what the customer did differently that kept the application working?

Here's how I did it:

I've done this with two tools, the Wise Windows Installer Editor and a 3rd party tool called FileSync. (http://www.fileware.com/products.htm#FileSync)

Examining the Files

Import both of your VSAs, and find the Read Only directory name associated with each. (e.g. Customer Layer is "C:\fslrdr\1" and your layer is "C:\fslrdr\3")

Use the FileSync utility to identify differences by pointing it at both directories. It will show you the files that only exist in one layer when compared to the other.

Checking the Registry

Next, find the registry keys for each layer (e.g. Customer Layer's keys are in HKEY_LOCAL_MACHINE\SOFTWARE\fslrdr\1\, and your layer's keys are in HKEY_LOCAL_MACHINE\SOFTWARE\fslrdr\3). Export the two keys to .reg files with regedit. Import the regkeys into their own MSI file in the Windows Installer Editor, and save them. Then use the 'Visual MSIDiff' function in the tools menu to compare the two MSIs. Go to the Registry Table, and you will find a list of keys that are highlighted when they differ.