Hey Toby,
Thanks for clarifying. So if I understand correctly you would like to access calendar, event and ticket data, which is managed by our plugins.
We don’t have an API or XML export, but you should be able to access all the details through the database. With some custom development you should be able to create the required XML structure from the data.
Though this might not be the answer you were hoping for, I hope I understood your question correctly. Is this it?
Andras