It's taken almost 12 months, but I finally finished a CalDAV plugin for SabreDAV. I've stayed within the standard as much as possible, but had to leave out some features that failed to meet the cost/benefit requirement.
It all uses PDO, and it's tested on both SQLite3 and MySQL.
SabreDAV is primarily intended as a toolkit to implement these protocols in different applications. Despite that, it should be reasonably easy to setup your own CalDAV server. …[Read more]