DAViCal is a server implementing the CalDAV protocol. It's solely a server, with minimal direct user interaction, instead relying on using CalDav clients, such as Apple's iCal.app, Thunderbird with Sunbird, or Evolution.
DAViCal is written in PHP and uses the PostgreSQL database as it's backend to store the calendar information. Currently it only supports PostgreSQL, but there is work to support other databases as well. Install PHP and PostgreSQL, along with the PHP bindings for PostgreSQL, with pacman:
pacman -S postgresql php php-pgsql