Sending Meeting Requests to Outlook via ASP.NET Mail Message
Numerous programs on my company deal with event registration. Naturally, that involves sending our employees meeting requests. Here’s the best way I’ve found so far for doing that. The long function at the end is from a web-service already in use for a few months.
Meeting Request
To make these ICS files dynamically, I use the .Net library DDay.iCal. It’s aewsome.
It took some trial and error, but at the end I was able to create events that work well for all versions of Outlook.
Unlike the solutions I’ve found on the web, this one doesn’t use the office interop thing, so I don’t need outlook installed on the server. I’m using a regular SMTP mail message and add the ICS as attachment.
Anyway, assuming you know how to send mails and how to generate the right ICS for your event (we’ll get to that later), this is the way to send it to Outlook:
First the variables:
//init the message with your defaults (from, to, subject, etc) MailMessage message = initMailMessage(); string iCal = initICal(parameters ...);
And the code that adds the attachment:
//Add the attachment, specify it is a calendar file.
System.Net.Mail.Attachment attachment =
System.Net.Mail.Attachment.CreateAttachmentFromString(
iCal, new ContentType("text/calendar"));
attachment.TransferEncoding = TransferEncoding.Base64;
attachment.Name = "EventDetails.ics"; //not visible in outlook
message.Attachments.Add(attachment);
sendMailMessage(message);
Ok. That’s probably disappointing, since you can’t just copy-paste this code and make it work. I’m including more code you may want to use, but first some rules for the ICS files you’re about to create:
Rules of Thumb
- Make sure to specify the Method property – should be Publish or Request. Outlook won’t accept the file without it.
- Add an Organizer – or Outlook 2007 won’t let people save the event.
- Add the meeting’s subject and description to the ICS file, but also as the mail’s subject and body. Outlook may display either one.
Now for that extra code.
This one is pretty simple – sends an SMTP message:
private static void sendMailMessage(MailMessage mailMessage)
{
string mailHost = "Ask.Someone.com";
SmtpClient smtpClient = new SmtpClient(mailHost, 25);
smtpClient.DeliveryMethod =
SmtpDeliveryMethod.PickupDirectoryFromIis;
smtpClient.Send(mailMessage);
}
This fine function creates the ICS:
[WebMethod(Description =
"Send an appointment with much details.")]
public void SendAppointment(string from, string to,
string title, string body, DateTime startDate,
double duration, string location, string organizer,
bool updatePreviousEvent, string eventId,
bool allDayEvent,
int recurrenceDaysInterval, int recurrenceCount)
{
iCalendar iCal = new iCalendar();
// outlook 2003 needs this property,
// or we'll get an error (a Lunar error!)
iCal.Method = "PUBLISH";
// Create the event
Event evt = iCal.Create();
evt.Summary = title;
evt.Start = new iCalDateTime(startDate.Year,
startDate.Month, startDate.Day, startDate.Hour,
startDate.Minute, startDate.Second);
evt.Duration = TimeSpan.FromHours(duration);
evt.Description = body;
evt.Location = location;
if (recurrenceDaysInterval > 0)
{
RecurrencePattern rp = new RecurrencePattern();
rp.Frequency = FrequencyType.Daily;
rp.Interval = recurrenceDaysInterval; // interval of days
rp.Count = recurrenceCount;
evt.AddRecurrencePattern(rp);
}
evt.IsAllDay = allDayEvent;
//organizer is mandatory for outlook 2007 - think about
// trowing an exception here.
if (!String.IsNullOrEmpty(organizer))
evt.Organizer = organizer;
if (!String.IsNullOrEmpty(eventId))
evt.UID = eventId;
//"REQUEST" will update an existing event with the same
// UID (Unique ID) and a newer time stamp.
if (updatePreviousEvent)
iCal.Method = "REQUEST";
// Save into calendar file.
iCalendarSerializer serializer =
new iCalendarSerializer(iCal);
//serializer.Serialize(@"iCalendar.ics");
string icalData = serializer.SerializeToString();
//send the iCal data. Also sends the subject and body
//on the mail.
SendAppointmentFromICalWithMailTitle(from, to,
icalData, title, body);
}
See Also:
- DDay.iCal – The iCal C# library.
- http://www.mavetju.org/programming/outlook-ics.php – This helped at the beginning, but written in Perl. Which is weird.
- http://chuckdotnet.blogspot.com/2007/10/send-outlook-meeting-requests-with.html – A VB.Net version, creating his own iCal and using Alternate Views.
- The iTip RFC – RFC 2446 – Had to read parts of it.
How not to Code: The String Identity Function
Yesterday I started working on a small system that’s been having some problems lately. Reviewing the code, I quickly came across the following function:
public static string IsNullToString(string _str)
{
string name = null;
if (_str != null)
{
name = _str.ToString();
}
return name;
}
Now, it seems that if that function receives a null it returns a null, and for other string it’s returning that string. Remembering that String is a sealed class and cannot be inherited, and that String.ToString() does very little, I fail to see why this function is used every time a string is printed out, 108 times in the code…
See Also:
Converting DataSets to Strongly-Typed DataSets
One of the first things shown to me when I started working in my company was Microsoft’s Data Access Application Block. One thing that bothered me was that I constantly had to convert DataSets it returned to strongly typed DataSets used in our programs, which usually meant merging the returned data set with a newly created DataTable. To relieve myself of those repeating tedious 6 lines of code, I made this little class that converts untyped DataSets and DataTables to a strongly typed DataTable.
In a first attempt to solve this problem, I used reflation to create an instance of the typed DataTable, so I had to pass the method the type of the DataTable, and cast it back to itself.
This is a more elegant solution, using generics:
/// <summary>
/// Helper methods and functions.
/// </summary>
/// <typeparam name="T">A strongly type DataTable.
/// A DataTable of type T will be returned from the DataSet.
/// </typeparam>
public static class DataSetAdapter<T>
where T : DataTable, new()
{
/// <summary>
/// Convert the first DataTable from a DataSet to a
/// strongly-typed data table.
/// </summary>
public static T convert(DataSet dataSet)
{
if (dataSet == null)
return null;
if (dataSet.Tables.Count == 0)
return null;
DataTable dataTable = dataSet.Tables[0];
return convert(dataTable);
}
/// <summary>
/// Convert an ordinary DataTable to a strongly-typed
/// data table.
/// </summary>
public static T convert(DataTable dataTable)
{
if (dataTable == null)
return null;
T stronglyTyped = new T();
// add data from the regular DataTable to the
// strongly typed DataTable.
stronglyTyped.Merge(dataTable);
return stronglyTyped;
}
}
The use of the class if pretty straightforward, just pass the DataSet and the Type:
DataSet employeesDataSet = OracleHelper.ExecuteDataset( connectionString, storedProcedure, parameters); EmployeesDataTable employees = DataSetAdapter<EmployeesDataTable>.convert(employeesDataSet);
Links:
Using Sharepoint’s File Type Icons
We have an old web part that displays documents from a list, and shows an icon next to file. After reading the list, the web part has a long “if-else” block that checks the files extension and displays the proper image. The images come from sharepoint template directory. I need to update this web part to display more file types icons. At first we though to create a list that maps images to extensions, but after little research I’ve decided to read sharepoint’s docicon.xml file.
First, we need to find the file docicon.xml. The file usually sits under
C:\Program Files\Common Files\Microsoft Shared\web server extensions\12\template\xml\docicon.xml
The xml directory is not mapped on the IIS, but we can still find it using this little trick:
string path = MapPathSecure("~/_layouts/");
path = Path.Combine(path, @"..\xml\docicon.xml");
Now all that’s left is to read the xml and add the data to a collection:
(This is actually the first time using XmlDataReader, but how wrong can I be?)
First, we define two members, for all files and the default icon, and then go through the XML nodes:
protected NameValueCollection fileTypeIcons;
protected string defaultIcon;
protected void readIconsXml()
{
XmlReader reader = XmlReader.Create(path);
reader.ReadToFollowing("ByExtension");
//find the first child. This doesn't skip the first node.
reader.ReadToFollowing("Mapping");
while (reader.ReadToNextSibling("Mapping"))
{
readOneNodeMapping(reader);
}
//find the default icon
reader.ReadToFollowing("Default");
reader.ReadToFollowing("Mapping");
defaultIcon = reader.GetAttribute("Value");
}
protected void readOneNodeMapping(XmlReader reader)
{
string tempKey = null;
string tempValue = null;
tempValue = reader.GetAttribute("Value");
tempKey = reader.GetAttribute("Key");
if ((tempKey != null) && (tempValue != null))
fileTypeIcons.Add(tempKey, tempValue);
}
And that’s it. We have all icons defined in the site ready in our project.
