Creating vCalendars programmatically in C#
Have you ever wanted to send out meeting requests from your code? Well I wanted to do just that today. And I didnt want to reference the Outlook dll's. I simply wanted to send an email to an attendee's email address.
After much searching and alot of useless code I found a gem at http://chuckdotnet.blogspot.com. I took the code there and modified it slightly so that you can send the meeting request to multiple recipients (attendees) at once.
below is the method that creates the system.net.mailmessage object with all the necessary alternateviews, so that when opened in outlook it behaves exactly like a meeting request that was sent from within outlook. remember to add using System.Net.Mail;using System.Net.Mime; to the top of your code.
public static MailMessage CreateMeetingRequest(DateTime start, DateTime end, string subject, string summary,
string location, string organizerName, string organizerEmail, string attendeeName, string attendeeEmail)
{
MailAddressCollection col = new MailAddressCollection();
col.Add(new MailAddress(attendeeEmail, attendeeName));
return CreateMeetingRequest(start, end, subject, summary, location, organizerName, organizerEmail, col);
}
public static MailMessage CreateMeetingRequest(DateTime start, DateTime end, string subject, string summary,
string location, string organizerName, string organizerEmail, MailAddressCollection attendeeList)
{
MailMessage msg = new MailMessage();
// Set up the different mime types contained in the message
System.Net.Mime.ContentType textType = new System.Net.Mime.ContentType("text/plain");
System.Net.Mime.ContentType HTMLType = new System.Net.Mime.ContentType("text/html");
System.Net.Mime.ContentType calendarType = new System.Net.Mime.ContentType("text/calendar");
// Add parameters to the calendar header
calendarType.Parameters.Add("method", "REQUEST");
calendarType.Parameters.Add("name", "meeting.ics");
// Create message body parts
// create the Body in text format
string bodyText = "Type:Single Meeting\r\nOrganizer: {0}\r\nStart Time:{1}\r\nEnd Time:{2}\r\nTime Zone:{3}\r\nLocation: {4}\r\n\r\n*~*~*~*~*~*~*~*~*~*\r\n\r\n{5}";
bodyText = string.Format(bodyText,
organizerName,
start.ToLongDateString() + " " + start.ToLongTimeString(),
end.ToLongDateString() + " " + end.ToLongTimeString(),
System.TimeZone.CurrentTimeZone.StandardName,
location,
summary);
AlternateView textView = AlternateView.CreateAlternateViewFromString(bodyText, textType);
msg.AlternateViews.Add(textView);
//create the Body in HTML format
string bodyHTML = "<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 3.2//EN\">\r\n<HTML>\r\n<HEAD>\r\n<META HTTP-EQUIV=\"Content-Type\" CONTENT=\"text/html; charset=utf-8\">\r\n<META NAME=\"Generator\" CONTENT=\"MS Exchange Server version 6.5.7652.24\">\r\n<TITLE>{0}</TITLE>\r\n</HEAD>\r\n<BODY>\r\n<!-- Converted from text/plain format -->\r\n<P><FONT SIZE=2>Type:Single Meeting<BR>\r\nOrganizer:{1}<BR>\r\nStart Time:{2}<BR>\r\nEnd Time:{3}<BR>\r\nTime Zone:{4}<BR>\r\nLocation:{5}<BR>\r\n<BR>\r\n*~*~*~*~*~*~*~*~*~*<BR>\r\n<BR>\r\n{6}<BR>\r\n</FONT>\r\n</P>\r\n\r\n</BODY>\r\n</HTML>";
bodyHTML = string.Format(bodyHTML,
summary,
organizerName,
start.ToLongDateString() + " " + start.ToLongTimeString(),
end.ToLongDateString() + " " + end.ToLongTimeString(),
System.TimeZone.CurrentTimeZone.StandardName,
location,
summary);
AlternateView HTMLView = AlternateView.CreateAlternateViewFromString(bodyHTML, HTMLType);
msg.AlternateViews.Add(HTMLView);
//create the Body in VCALENDAR format
string calDateFormat = "yyyyMMddTHHmmssZ";
string bodyCalendar = "BEGIN:VCALENDAR\r\nMETHOD:REQUEST\r\nPRODID:Microsoft CDO for Microsoft Exchange\r\nVERSION:2.0\r\nBEGIN:VTIMEZONE\r\nTZID:(GMT-06.00) Central Time (US & Canada)\r\nX-MICROSOFT-CDO-TZID:11\r\nBEGIN:STANDARD\r\nDTSTART:16010101T020000\r\nTZOFFSETFROM:-0500\r\nTZOFFSETTO:-0600\r\nRRULE:FREQ=YEARLY;WKST=MO;INTERVAL=1;BYMONTH=11;BYDAY=1SU\r\nEND:STANDARD\r\nBEGIN:DAYLIGHT\r\nDTSTART:16010101T020000\r\nTZOFFSETFROM:-0600\r\nTZOFFSETTO:-0500\r\nRRULE:FREQ=YEARLY;WKST=MO;INTERVAL=1;BYMONTH=3;BYDAY=2SU\r\nEND:DAYLIGHT\r\nEND:VTIMEZONE\r\nBEGIN:VEVENT\r\nDTSTAMP:{8}\r\nDTSTART:{0}\r\nSUMMARY:{7}\r\nUID:{5}\r\nATTENDEE;ROLE=REQ-PARTICIPANT;PARTSTAT=NEEDS-ACTION;RSVP=TRUE;CN=\"{9}\":MAILTO:{9}\r\nACTION;RSVP=TRUE;CN=\"{4}\":MAILTO:{4}\r\nORGANIZER;CN=\"{3}\":mailto:{4}\r\nLOCATION:{2}\r\nDTEND:{1}\r\nDESCRIPTION:{7}\\N\r\nSEQUENCE:1\r\nPRIORITY:5\r\nCLASS:\r\nCREATED:{8}\r\nLAST-MODIFIED:{8}\r\nSTATUS:CONFIRMED\r\nTRANSP:OPAQUE\r\nX-MICROSOFT-CDO-BUSYSTATUS:BUSY\r\nX-MICROSOFT-CDO-INSTTYPE:0\r\nX-MICROSOFT-CDO-INTENDEDSTATUS:BUSY\r\nX-MICROSOFT-CDO-ALLDAYEVENT:FALSE\r\nX-MICROSOFT-CDO-IMPORTANCE:1\r\nX-MICROSOFT-CDO-OWNERAPPTID:-1\r\nX-MICROSOFT-CDO-ATTENDEE-CRITICAL-CHANGE:{8}\r\nX-MICROSOFT-CDO-OWNER-CRITICAL-CHANGE:{8}\r\nBEGIN:VALARM\r\nACTION:DISPLAY\r\nDESCRIPTION:REMINDER\r\nTRIGGER;RELATED=START:-PT00H15M00S\r\nEND:VALARM\r\nEND:VEVENT\r\nEND:VCALENDAR\r\n";
bodyCalendar = string.Format(bodyCalendar,
start.ToUniversalTime().ToString(calDateFormat),
end.ToUniversalTime().ToString(calDateFormat),
location,
organizerName,
organizerEmail,
Guid.NewGuid().ToString("B"),
summary,
subject,
DateTime.Now.ToUniversalTime().ToString(calDateFormat),
attendeeList.ToString());
AlternateView calendarView = AlternateView.CreateAlternateViewFromString(bodyCalendar, calendarType);
calendarView.TransferEncoding = TransferEncoding.SevenBit;
msg.AlternateViews.Add(calendarView);
// Adress the message
msg.From = new MailAddress(organizerEmail);
foreach (MailAddress attendee in attendeeList)
{
msg.To.Add(attendee);
}
msg.Subject = subject;
return msg;
}