Building a Meeting Scheduler for Android using the new Calendar API

Though developers are quite comfortable thinking in abstractions, we still find a lot of value in code examples and fully developed sample applications. Judging by the volume of comments, tweets, and git checkouts of the Au-to-do sample code we released a few weeks ago, our readers agree.

For Google Apps API developers who want to get started writing mobile apps, here’s a great new resource: a sample application that integrates Google Calendar API v3 with Android and illustrates best practices for OAuth 2.0. This meeting scheduler app built by Alain Vongsouvanh gets the user’s contact list, lets users select attendees, and matches free/busy times to suggest available meeting times. It provides a simple Android UI for user actions such as attendee selection:

The sample code for Meeting Scheduler demonstrates many key aspects of developing with Google Apps APIs. After authorizing all required access using OAuth 2.0, the Meeting Scheduler makes requests to the Calendar API. For example, the class FreeBusyTimesRetriever queries the free/busy endpoint to find available meeting times:

FreeBusyRequest request = new FreeBusyRequest();

request.setTimeMin(getDateTime(startDate, 0));
request.setTimeMax(getDateTime(startDate, timeSpan));

for (String attendee : attendees) {
  requestItems.add(new FreeBusyRequestItem().setId(attendee));
}
request.setItems(requestItems);

FreeBusyResponse busyTimes;
try {
  Freebusy.Query query = service.freebusy().query(request);
  // Use partial GET to retrieve only needed fields.
  query.setFields("calendars");
  busyTimes = query.execute();
      // ...
} catch (IOException e) {
  // ...
}

In this snippet above, note the use of a partial GET request. Calendar API v3, along with many other new Google APIs, provides partial response with GET and PATCH to retrieve or update only the data fields you need for a given request. Using these methods can help you streamline your code and conserve system resources.

For the full context of all calls that Meeting Scheduler makes, including OAuth 2.0 flow and the handling of expired access tokens, see Getting Started with the Calendar API v3 and OAuth 2.0 on Android. The project site provides all the source code and other resources, and there’s a related wiki page with important configuration details.

We hope you’ll have a look at the sample and let us know what you think in the Google Apps Calendar API forum. You’re welcome to create a clone of the source code and do some Meeting Scheduler development of your own. If you find a bug or have an idea for a feature, don’t hesitate to file it for evaluation.

Eric Gilmore   Eric is a technical writer working with the Developer Relations group. Previously dedicated to Google Enterprise documentation, he is now busy writing about various Google Apps APIs, including Contacts, Calendar, and Provisioning.