CalCore is an advanced, flexible calendaring component for Python. It allows the Python developer to write advanced calendaring applications either using their own event storage or integrating with external calendar servers. It features support for private calendars, shared calendars, resource booking, integration with iCalendar clients (Apple iCal, Mozilla Sunbird, KOrganizer) using the iCalendar protocol, invitation workflow, meeting support, including helper functions to look for free time, and recurring event support. It is being used as the core of Nuxeo's CalZope and CPSSharedCalendar products.
The Darwin Calendar Server is a standards-compliant server that allows multiple users to collaboratively share calendaring information. It provides a shared location on the network to store schedules, and allows users to send each other and manage invitations. In order to provide interoperability with multiple calendaring clients, the server implements the CalDAV protocol, which is an extension of WebDAV, which is in turn an extension of HTTP.