How do I create an "internet calendar subscription" for Outlook?

Question

Currently, the user adds a "new internet calendar", but it's a one-time download of the ICS file. I want the user to click a button to get his personal calendar added as a subscription to Outlook. I want the automatically updating "internet calendar subscription".

Like in SharePoint, the button called "Connect to Outlook" which adds the calendar you're viewing to your Outlook as an automatically syncing calendar.

Answer 1

Creating iCals in C# and this CodeProject post tell me you should use the DDay iCal Library.

DDay.iCal is an iCal (RFC 5545) class library for .NET 2.0 and above, Silverlight. It aims at being as RFC 5545 compliant as possible, while targeting compatibility with popular calendaring applications, like Apple iCal, Outlook 2007, etc.

Some sample code of iCal + MVC + DDay.iCal

public ActionResult iCalendar(string DownloadFileName)
{
    DDay.iCal.iCalendar iCal = new DDay.iCal.iCalendar();

    Event evt = iCal.Create<Event>();
    evt.Start = iCalDateTime.Today.AddHours(8);
    evt.End = evt.Start.AddHours(18); // This also sets the duration
    evt.Description = "The event description";
    evt.Location = "Event location";
    evt.Summary = "18 hour event summary";

    evt = iCal.Create<Event>();
    evt.Start = iCalDateTime.Today.AddDays(5);
    evt.End = evt.Start.AddDays(1);
    evt.IsAllDay = true;
    evt.Summary = "All-day event";

    ISerializationContext ctx = new SerializationContext();
    ISerializerFactory factory = new DDay.iCal.Serialization.iCalendar.SerializerFactory();
    IStringSerializer serializer = factory.Build(iCal.GetType(), ctx) as IStringSerializer;

    string output = serializer.SerializeToString(iCal);
    var contentType = "text/calendar";
    var bytes = Encoding.UTF8.GetBytes(output);

    return File(bytes, contentType, DownloadFileName);
}