I am trying to create a new installer (using Wix) which will going to substitute the current one (InstallShield). Problem is many clients already have the application installed using the current installer. I need my new Wix installer to detect currently installed application perform the update or force the user to uninstall current application before running the new Wix installer.
I am new with creating installers. I need to know which GUIDs (and version numbers) must be the same for the system to know this is actually the same application just a new version. I didn't create the old InstallSheeld installer but I do have access to its code.
Thank you very much.
To uninstall the old InstallShield package, you should find out your old upgrade code and use that within your new WiX installer and do a major upgrade (which will ensure that the old package is uninstalled and removed). Check this Wix Upgrade document for doing the major upgrade.
Since we are on the topic, you can also make use of the Dark.exe to convert the current MSI into WiX source files.