[Interest] Qt Installer framework: installer that installs updates, not only new installs

[Wiebe Cazemier]

Hello, 

I'm creating installers for my current project (online and offline) with Qt Installer Framework 1.5. The installer works, but I'm having problems with using the installer to install updates. 

I have these issues:

[1] when running the offline or online installer again for a new version, it won't automatically detect that it's updating existing software. Instead, it will complain about the target directory already existing.

[2] In 'programs and features' in Windows, opening the uninstaller also gives you the option to look for updates. When I actually put an update on the repository URL, the installer does nothing when I press next. When there is no update, it does know enough to say 'no updates available'.

So, how do I make my installer update-aware? I case of [1], is it a matter of scripting an uninstall of the old version? If so, how :)?

And, another issue: how best to implement a self-updater in the software I'm making? Simply download the XML from the repository URL and if there is an update, download and run the offline or online installer?

Regards,

Wiebe