We use InstallShield InstallScript projects to create our installers and are looking for a good way to migrate to the WiX Toolset. As far as I know there is no UpgradeCode (as for MSI) to update from an Installshield InstallScript project to a WiX project.
The only solution I found so far is:
Is there a better way?
Ok after all those comments I think I understand why this is such an issue. Unfortunately I don't think there is a very simple way to do waht you want to do.
I think your method will be the only real way to migrate from this isntallscript setup based installation. There should be some registry entry in HKLM/SOFTWARE/Microsoft/Windows/CurrentVersion/Uninstall that relates to your product. In here there may be a uninstall command which you could read into a Variable from your burn package and pass that value as a property to your msi.
In you MSI you can have 3 custom actions specifically related to upgrading from the installshield product installation. All these tasks should be deferred custom actions so that they can run with administrator elevation. The first task should copy all the configuration settings to a safe place (generally %temp%\ProductConfig\ would be fine). The second part after saving the configuration would run that uninstall command to remove the product, you may need to append /q or something to make it run passively/quietly. Then at the end of the installation you can copy back the configuration files from temp.
Each of the custom actions should run conditionally on whether or not the property you passed in is set to something. I would schedule the copy cofig after InstallInitialize, the uninstall after the copy and the restore before InstallFinalize just to ensure that everything is copied over after the installer puts all the files on the system.
Ideally you would like to get everything to upgrade without the user needing to interact except in a minimal way by clicking next and Install.
I've only dealt with InstallShield enough to know I really don't like it so if someone else knows more and knows of a better way to do it they'll hopefully chime in.