Data Sources: Making Homes Smart - Smart Home Automation with Linux and Raspberry Pi - page 205

undeniable—having your data available from any machine in the world (with a network connection) provides a truly
location-less digital lifestyle. But your home is not, generally, location-less. Therefore, you need to consider what type
of useful information about yourself is held on other computers and how to access it.
Calendar
Groupware applications are one of the areas in which Linux desktop software has been particularly weak. Google has
entered this arena with its own solution, Google Calendar, which links into your e-mail, allowing daily reminders to
be sent to your inbox as well as to the calendars of other people and groups.
Calendar events that occur within the next 24 hours can also be queried by SMS, and new ones can be added
by sending a message to GVENT (48368). Currently, this functionality is available only to U.S. users but is a free HA
feature for those it does affect.
The information within the calendar is yours and available in several different ways. First, and most simply, it can
be embedded into any web page as an iframe:
<iframe src=" http://www.google.com/calendar/embed?src=my_email_address «
%40gmail.com&ctz=Europe/London " style="border: 0" width="800" height="600" «
frameborder="0" scrolling="no"></iframe>
This shows the current calendar and allows to you edit existing events. However, you will need to refresh the
page manually for edits to become visible, and new events cannot be added without venturing into the Google
Calendar page.
The apparent security hole that this public URL opens is avoided, because you must already be signed into your
Google account for this to work; otherwise, the login page is shown.
Alternatively, if you want your calendar to be visible without signing into your Google account, then you can
generate a private key that makes your calendar data available to anyone that knows this key. The key is presented as a
secret URL.
To discover this URL, go the Settings link at the top right of your Google Calendar account, and choose Calendars.
This will open a list of calendars that you can edit and those you can't. Naturally, you can't choose to expose the
details of the read-only variants. So, select your own personal calendar, and scroll down to the section entitled Private
Address. The three icons on the right side, labeled XML, ICAL, and HTML, provide a URL to retrieve the data for your
calendar in the format specified. A typical HTML link looks like this:
http://www.google.com/calendar/embed?src=my_email_address «
%40gmail.com&ctz=Europe/London&pvttk=5f93e4d926ce3dd2a91669da470e98c5
The XML version is as follows:
http://www.google.com/calendar/feeds/my_email_address «
%40gmail.com/private-5f93e4d926ce3dd2a91669da470e98c5/basic
The ICAL version uses a slightly different format:
http://www.google.com/calendar/ical/my_email_address «
%40gmail.com/private-5f93e4d926ce3dd2a91669da470e98c5/basic.ics
The latter two are of greater use to us, since they can be viewed (but not edited) in whatever software
you choose.