Syncing events with Google Calendar

I'm writing a service that needs an up-to-date information on a user's calendar. However, I have yet to find a way other than regular polling to receive updates from GCal. Is it possible to set up some开发者_如何学运维 kind of push notification or an event list diff transmission?

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(Disclaimer: I work for Google, and I worked on Google Mobile Sync, specifically calendar sync, but in this answer and everything else I write on this site, I am writing as an individual and not representing Google.)

I don't believe there's a public notification API, I'm afraid. As far as I'm aware, you will need to poll. However, you can of course ask for changes since a particular timestamp; it's not like you have to download the whole calendar every time.

On a secondary note: good luck! I certainly didn't appreciate just how complicated calendaring was until I started working on it...