The Database subsystem uses the Berkeley DB from Sleepycat Software (the database API is not public). The Database subsystem stores and retrieves calendar data to and from the database, including events, todos (tasks), and alarms. Calendar data is based on iCalendar format, and the schema used for Calendar Server data is a super set of the iCalendar standard.
The Database subsystem returns data in a low-level format, and the Core UI generator then translates the low-level data and sends it through WCAP.
For a distributed calendar database, Calendar Server uses the Distributed Wire Protocol (DWP) to provide a networking capability. For more information, see 1.10.5 Distributed Database Service: csdwpd in Calendar Server Version 6.3.
For information about the calendar database, refer to Chapter 16, Administering Calendar Server Databases with the csdb Utility.