I might add, simply using files for user data – documents, address
book, calendar – is totally plausible to me. Make these files
non-dotfiles in the home directory. Maybe make them a single file with
a MIME type, so you can just drag and drop your calendar or address
book between systems.
Or use dotfiles. e.g. metacity uses dotfiles to save sessions.
Files lack change notification and make it harder to write
configuration UI such as a generic management tool or the control
center. They make it hard to do lockdown in a generalized way and
support a central data store for an entire network. But this stuff
doesn’t really matter if the file is genuinely data, rather than
preferences. The home directory is where user data lives.
(This post was originally found at http://log.ometer.com/2004-03.html#1)