Aim

• Always have up-to-date Facebook events, which I’m attending to, in my calendar (I use Google Calendar)
• Additionally sync to other calendar-related services, like Doodle
• Use LAMP server to update (import-export) calendar

Existing solutions

Standard Facebook events export

• webcal: URL is provided by Facebook for all upcoming events. URL is compatible with Google Calendar.
• There were problems with events, which description did contain special (national) characters. Generated iCalendar data was invalid and unreadable by Google Calendar (all events weren’t available)
• It is not possible to filter events in any way. All events, even declined ones, are listed.

Facebook Freedom

• Possibility to select (filter) events by attending status. For example hide all declined and tentative
• Permanent URL expires and must be recreated regularly
• Uses third party server

To implement

• Use Facebook Graph API
• Download list of upcoming (all?) events
• Convert to iCal (whatever compatible to Google Calendar) format
• Place as static file (with permanent URL) on my running Apache server
• Add the calendar file URL to Google Calendar
• Script (automate) steps above for updating the file
  • Read events
  • Convert
  • Update static file
• Schedule the script via cron
• PROFIT!

Framework comparison for converter

bash

• Input: curl
  • A framework (functions library) for parsing JSON Facebook Graph format is required (implement from scratch?)
• Output: echo to text file
  • A framework (functions library) to support iCalendar format required (implement from scratch?)
  • There may be problems with text encoding (charset)

Java

• Input: Existing Facebook API frameworks
  • Spring Social Facebook
  • RestFB
• Output: iCal4j

Security

• Calendar data must be only accessible for authorized (trusted) clients: me, Google Calendar
  • Data should be requested over an encrypted channel (HTTPS) to prevent “man in the middle” attack
  • It seems to be no way to hide URL from proxy in the middle, however the proxy must be normally trusted service.
• Clarified:
  • Google Calendar supports custom CA certificates when reading calendar data over HTTPS. It is possible to add test iCalendar data from https URL on the test server.
• When using a “secret” URL for the static file on Apache server, make sure, that automatic directory index generation (directory listing) is switched off (at least within a folder with the file). Otherwise it will be possible to browse all available files and find out the exact data URL. See configuration example below:

<Directory /usr/local/apache2/htdocs/dontlistme>
 Options -Indexes
</Directory>