Outlook Appointments, ASP and vCalendar Page 2
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The Custom VB vCalendar Class and DLL
I created a custom Visual Basic class to serve as a wraper around the process of
creating the vCalendar text file. The class does limited date validation (that
responsibility is left to the ASP code), but does some time zone adjustment and
parses the date into a vCalendar-ready text string, prior to writing the formatted
text to a .vcs file.
This class exposes only the most basic properties of the Outlook Appointment item.
If more properties need to be set, you could determine the format by following the
instructions on the previous page for using Outlook to create a vCalendar template
and add those properties to the VB Class. Note that Property Let and Property Get
procedures are used to populate the following private variables:
Private dtmStart As Date
Private dtmEnd As Date
Private strLocation As String
Private strSubject As String
Private strDescription As String
Private strOutputFilePath As String
Private intTimeZoneBias As Integer
The class has only one Method which parses the variables into strings and creates the
.vcs file. This method returns the path to the .vcs file as a string value. This file path
is needed by the ASP page, as we will see later. Notice the relatively simple code
involved with this proces:
Public Function CreateVCSEvent() As Boolean
On Error Resume Next
Dim strStartDate As String
Dim strEndDate As String
Dim strToday As String
Dim iFileNumber As Integer
Dim strVCalFile As String
' VCS uses GMT so all values must be adjusted according to
' your Time Zone. Mountain Time (Denver) is -7
' TimeZone Offset from GMT is always Negative. Make it positive.
intTimeZoneBias = intTimeZoneBias * (-1)
dtmStart = DateAdd("h", intTimeZoneBias, dtmStart)
dtmEnd = DateAdd("h", intTimeZoneBias, dtmEnd)
' Format user-supplied data in VCS required format.
' Note that the style "Hhnnss" returns time in 24-hour format.
strStartDate = Format(dtmStart, "yyyymmdd") & "T" & Format(dtmStart, "Hhnnss")
strEndDate = Format(dtmEnd, "yyyymmdd") & "T" & Format(dtmEnd, "Hhnnss")
' If no date was passed, for example, "8:30 am", the date defaults to 12/30/1899
' Since this date is of no value, test for it and convert it to the current date.
' (Code could also be added to handle dates passed with no TIME value.)
If Left(strStartDate, 8) = "18991230" Then
strToday = Format(Date, "yyyymmdd")
strStartDate = strToday & Mid(strStartDate, 9)
End If
If Left(strEndDate, 8) = "18991230" Then
strToday = Format(Date, "yyyymmdd")
strEndDate = strToday & Mid(strEndDate, 9)
End If
' Create the file based on the path provided by the user. Use the
' Subject as the name of the file.
iFileNumber = FreeFile
If Right(strOutputFilePath, 1) = "\" Then
strVCalFile = strOutputFilePath & strSubject & ".vcs"
Else
strVCalFile = strOutputFilePath & "\" & strSubject & ".vcs"
End If
' Create the .vcs file. Use the Start and End dates and Subject as a unique UID
Open strVCalFile For Output As #iFileNumber
Print #iFileNumber, "BEGIN:VCALENDAR"
Print #iFileNumber, "VERSION:1.0"
Print #iFileNumber, "BEGIN: VEVENT"
Print #iFileNumber, "DTStart:" & strStartDate
Print #iFileNumber, "DTEnd:" & strEndDate
Print #iFileNumber, "Location;ENCODING=QUOTED-PRINTABLE:" & strLocation
Print #iFileNumber, "SUMMARY;ENCODING=QUOTED-PRINTABLE:" & strSubject
Print #iFileNumber, "DESCRIPTION;ENCODING=QUOTED-PRINTABLE:" & strDescription
Print #iFileNumber, "UID:" & strStartDate & strEndDate & strSubject
Print #iFileNumber, "PRIORITY:3"
Print #iFileNumber, "End:VEVENT"
Print #iFileNumber, "End:VCALENDAR"
Close #iFileNumber
' Note that more properties could easily be added
End Function
In order for this class to be used by our ASP page, it is necessary to compile it into
an Active-X dll and register it on the server. The download for
this article includes a VB project with the code and an ASP page to execute it. I named
the DLL VCSWrap and if you unzip the contents of the download into a folder named vCal
under the C:\Inetpub\wwwroot\ directory, then you can register it with this line:
regsvr32 C:\Inetpub\wwwroot\Vcal\VCalWrap.dll
