Handling multiple application versions via Commandline

I h开发者_运维百科ave a situation where we are releasing a new version of our application, and I was wondering how other people handle the situation where they have a datafile and opening/editing that file.

In the previous version of the application users could make a backup file which contains all the necessary parts of the system to transport and restore that file onto another system. Except the file contains no version information.

If the user uninstalls our old version and installs the new version, then these backup files work perfectly.

If the user upgraded to our new version of the application, and also leaves the old version installed then the backups that they took previously when they open (via Double clicking) then they open in the new version BUT the user probably expected them to open in the previous version.

Which of the following choices would be the nicest to the user?

1. Open the file with the new version and leave it be, they installed the new version so that's life

2. Present a dialog box showing that they have 2 versions installed and what version do they want to open the file with

3. If the file is from the old version, automatically launch the old version from the new version passing across the same command line parameters that came in.

If the file is from new version, open new version. If file is from old version, show dialog box to select