G Suite Developers Blog: Extending Google Calendar to support cross-organizational scheduling

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Extending Google Calendar to support cross-organizational scheduling

April 2, 2010

Editor's Note: This post was written by Gilad Goraly from ScheduleOnce, a company that provides meeting scheduling solutions for Google Calendar. We invited ScheduleOnce to share their experiences building an application on top of Google Apps utilizing some of our APIs.

The Google Apps Marketplace installation process adds a link in Google’s universal navigation and enables Single Sign On (SSO).

The Google Gadget framework is used to include a gadget in Google Calendar and in Gmail.

The Google Calendar API is used to seamlessly integrate with the user’s calendar.

Installation from the Google Apps Marketplace

A quick and easy installation process and a link in Google’s universal navigation

Single Sign On (SSO)

Installation process

The Administrator approves a Two Legged OAuth (2LO) calendar API permission for all domain users. This means that ScheduleOnce can access the calendar API of every user in the domain without requiring the user to re-enter their credentials. This is very convenient for the user.

Every user in the domain automatically gets a link to a Personal ScheduleOnce Dashboard on his Google universal navigation. This is set in the installation manifest:

<Extension id="oneBarLink" type="link">
<Name>ScheduleOnce</Name>
<Url>http://apps.scheduleonce.com/render.aspx?source=${DOMAIN_NAME}&amp;page=dashboard</Url>
</Extension>

The administrator selects a URL and a logo for the application. We use the SSO and ${DOMAIN_NAME} parameter to verify that the user is part of the domain so one cannot maliciously create ScheduleOnce instances. We also use the ${DOMAIN_NAME} parameter for presenting the domain custom logo:
https://www.google.com/a/${DOMAIN_NAME}/images/logo.gif?alpha=1

Single Sign On (SSO)// Create a service for making 2LO requests
GOAuthRequestFactory requestFactory = new GOAuthRequestFactory("cl", "yourCompany-YourAppName-v1");
requestFactory.ConsumerKey = <CONSUMER_KEY>;
requestFactory.ConsumerSecret = <CONSUMER_SECERT>;
CalendarService service = new CalendarService(requestFactory.ApplicationName);
service.RequestFactory = requestFactory;Gadgets in Google Calendar, Gmail and the Start Pagefunction initGadget(){
//Initializing the gadget tabs
tabs.addTab("Pending", {
contentContainer: document.getElementById("pending_id"),
callback: callback
});
tabs.addTab("Scheduled", {
contentContainer: document.getElementById("scheduled_id"),
callback: callback
});
tabs.displayTabs(false);
refresh();

//Initializing the OpenSocial data request
var idspec = opensocial.newIdSpec({ "userId" : "OWNER"});
var req = opensocial.newDataRequest();
req.add(req.newFetchPersonRequest(opensocial.IdSpec.PersonId.OWNER), "get_owner");
req.send(openSocialResponse);
}function makePOSTRequest(){
var url = baseURL + "GadgetHandler.aspx";
var postdata = {opensocialid : openSocialID};
var params = {};
postdata = gadgets.io.encodeValues(postdata);
params[gadgets.io.RequestParameters.METHOD] = gadgets.io.MethodType.POST;
params[gadgets.io.RequestParameters.POST_DATA]= postdata;
params[gadgets.io.RequestParameters.CONTENT_TYPE] = gadgets.io.ContentType.TEXT;
gadgets.io.makeRequest(url, responseHandler, params);
}Integration with Google Calendar

Getting the user's busy times: Since availability is dynamic and dependent on the current calendar status we update it every time it is needed. This ensures there will never be any double booking in the user’s calendar.

// Retrieving the calendar events for a time frame
EventQuery query = new EventQuery();
string uriString = "https://www.google.com/calendar/feeds/" + username + "/private/full?ctz=utc";

query.Uri = new Uri(uriString);
query.StartTime = <time frame start>;
query.EndTime = <time frame end>;

EventFeed calFeed = service.Query(query);
AtomEntryCollection entryColl = calFeed.Entries;

Creating a calendar with tentative meeting times: ScheduleOnce cannot "lock" certain timeframes until the scheduling process is over. For this reason we create a tentative meetings calendar that can be used to see times that were proposed for a meeting.

// Creating a calendar
CalendarEntry calendar = new CalendarEntry();
calendar.Title.Text = <calendar title>;
calendar.Summary.Text = <calendar description>;
calendar.TimeZone = <calendar timezone>;
Uri postUri = new Uri("https://www.google.com/calendar/feeds/default/owncalendars/full");
CalendarEntry createdCalendar = (CalendarEntry)service.Insert(postUri, calendar);

Scheduling the meeting and sending the invitation via Google Calendar: When the meeting organizer schedules the meeting, a meeting entry is created in his calendar and meeting invitations are sent to all attendees.

// Creating a meeting
EventEntry entry = new EventEntry();
entry.Title.Text = <meeting Title>;
When eventTime = new When(<meeting startTime>, <meeting endTime>);
entry.Times.Add(eventTime);
Uri postUri = new Uri("https://www.google.com/calendar/feeds/" + username + "/private/full?ctz=utc");
AtomEntry insertedEntry = service.Insert(postUri, entry);

Tip: Use Calendar API calls in a batch when possible to increase performance.Using Documentation and Help Forumswww.scheduleonce.comBy Gilad Goraly, ScheduleOnce