For about the last year I have abandoned the use of my workplace calendar system (based on Microsoft Outlook and Exchange) and using paper diaries in favour of Google Calendar. This solution offers a number of advantages for me, it is entirely web based, it is platform independent and I can even see my appointments on my mobile phone thanks to the mobile version. I've also been using Mozilla Thunderbird, an excellent open source email program, for years. So it was very interesting to read Rob Parsons' post on getting these two technologies working together through a couple of add ons. It looks like Mozilla Thunderbird could become the Personal Information Manager of choice for those who use Web 2.0 services to manage their affairs thanks to an increasing number of addons. On the horizon is also an add on to integrate it with the popular web based task management system Remember the Milk, and apparently it is already possible to integrate Thunderbird with Google Mail.

You'll need two add ons to get this working, the first is Mozilla Lightning which adds calendar and tasks functionality to Thunderbird. Within the last couple of days version 0.9 has been released which contains many big fixes. Older versions are available in the Ubuntu package repositories, but it is best to use the latest version. Now if you are a 64bit Linux user you might get tripped up on the main add ons page, the button may say "Download Now (Linux), but it means 32 bit Linux, and that version of Lightning won't work on your system. Fortunately there is a 64 bit version and this is under the main project site at: http://www.mozilla.org/projects/calendar/, you can click on this link to get the version you need. You should download the add on for your operating system to your local hard disc, then open up Thunderbird, go to Tools -> Add-ons -> Install, find the file you downloaded and install it. You may have to restart Thunderbird to get it to pick up the extension. 

Now you will have full local calendar and task functionality in Thunderbird. You can switch between the views by going to "Go" and selecting the view required. By default you will be shown a screen with your emails on it and a small calendar panel to the right. The next step is to get Lightning to have the same information in it as Google Calendar. At the end of these step we will be able to see the information in Google Calendar and also update it from Thunderbird. You'll need to download the Provider for Google Calendar version 0.5 (this goes with Lighting 0.9) and install it in the same was as Lighting, after a restart of Thunderbird (all of these restarts could start to remind me of MS Windows!) you will be able to get at your Google Calendar by:

1. Go to the Calendar view by selecting Go -> Calendar 
2. On the left hand side under "Calendar" right click and select "New Calendar"
3. You will now see a wizard and you should pick "On the Network" to the section marked "Locate calendar"
4. You should now see a section marked "Create a new calendar" - select "Google Calendar"
5. You now need to locate the correct address of your calendar:
   • In a browser open Google Calendar
   • Click on "Settings" by your sign in name at the top right of the screen
   • Click on the "Calendars" tab next to "General"
   • Under "My Calendars" click on the name of the calendar you want to link to (the leftmost column)
   • At the bottom of the next screen will be some buttons beside the text "Private address", right click over the button marked "ICAL" and select "Copy Link Location"
6. Paste the address found by following the steps above into the "Location" box
7. You should now be prompted for your Google user name and pasword. After you enter these you will see your Google Calendar in Thunderbird!
8. I would recommend you delete the default calendar "Home" by right clicking over it and selecting "Delete" unless you particularly need it.

Go ahead and test out the calendar, you should find that entering a new appointment in Lightning also updates Google Calendar. This makes for a great addition to Thunderbird provides a nice way to use Google Calendar without having to visit the web site every time. It should be possible to do things like accept invitations sent by mail and add the details to your calendar automatically, but I haven't tried this yet.