Team calendar

The code in this article will show you how to build a web page that can:

• retrieve information from the Outlook calendars of your team members
• show this information in a single neat overview.

The code is written in VB.NET, but it can easily be converted into C# or any other language.

Configuration

Just copy all the files in the sample code to the root of an existing web site, but take care not to overwrite any existing files.
If a file named "index.aspx" already exists, just copy the file from the sample code after renaming it to something else, e.g. "calendar.aspx".
If a file named "web.config" already exists, don't overwrite it, this will destroy all the existing settings. Just open the existing "web.config" file, and add these 5 lines to the existing "appSettings" settings.

<add key="ServerName" value="ExchangeServerName"/>
<add key="WindowsDomain" value="OURDOMAIN"/>
<add key="UserForReadingCalendars" value="ExchReader"/>
<add key="PwdForReadingCalendars" value="secret"/>
<add key="Usernames" value="Anne,John,Fred,Kate"/>    

Then, change the value for each of these keys according to your own situation:

1. The "ServerName" setting is the name of the Exchange server on the network
2. The "WindowsDomain" setting is the name of the Windows domain controlling the user database
3. The user indicated in the key "UserForReadingCalendars" should at least have read permissions on the Outlook calendars. Each user listed in the 5th setting should grant this permission through Outlook's configuration settings. For Outlook 2003, see Share my Outlook calendar.
4. The "PwdForReadingCalendars" is the password of the user in the key "UserForReadingCalendars"
5. The last setting "Usernames" is a list of your team members, separated by commas. The names should be the names of their mail boxes (i.e. the logon names). These users should share their calenders to the user that was set in the 3rd setting.

How it works

The first part is to retrieve the calendars from the Exchange server. There are several ways to do this:

• ADO (ExOLEDB provider)
• CDOEX
• WebDAV

I chose the WebDAV method. It has one inconvenience: it's slow when there are lots of calendars to be read.

In this case, we need to create a request that will read the calendar on a particular date. This is the code that will retrieve all the events in the calendar, especially the properties: start, end, busy status, and of course: the content:

Function LookUpCalendar(ByVal Name As String, ByVal dDate As DateTime) As XmlDocument 
   Dim strURL As String = "http://" & ConfigurationSettings.AppSettings("ServerName") & "/exchange/" & Name & "/calendar/" 
   Dim strRequest As String = "<?xml version=""1.0""?>" & _
       "<g:searchrequest DAV:?? xmlns:g="">" & _
       "<g:sql>SELECT ""urn:schemas:calendar:location"", ""urn:schemas:httpmail:subject"", " & _
       """urn:schemas:calendar:dtstart"", ""urn:schemas:calendar:dtend"", " & _
       """urn:schemas:calendar:busystatus"", ""urn:schemas:calendar:instancetype"" " & _
       "FROM Scope('SHALLOW TRAVERSAL OF """ & strURL & """') " & _
       "WHERE NOT ""urn:schemas:calendar:instancetype"" = 1 " & _
       "AND ""DAV:contentclass"" = 'urn:content-classes:appointment' " & _
       "AND ""urn:schemas:calendar:dtstart"" > '" & _
       String.Format("{0:yyyy/MM/dd}", dDate) & " 00:00:00' " & _
       "AND ""urn:schemas:calendar:dtend"" < '" & _
       String.Format("{0:yyyy/MM/dd}", dDate.AddDays(1)) & " 00:00:00' " & _
       "ORDER BY ""urn:schemas:calendar:dtstart"" ASC" & _
       "</g:sql></g:searchrequest>"     
    Dim strStatusText As String = "" 
    Dim Status As Integer 
    Dim ResponseXmlDoc As XmlDocument = SendRequest("SEARCH", strURL, strRequest, strStatusText, Status) 
    'Display the results. 
    If (Status >= 200 And Status < 300) Then 
       AddInfo("Success! " & "Result = " & Status & ": " & strStatusText, 2)
       Return ResponseXmlDoc 
    ElseIf Status = 401 Then 
       AddInfo("<BR /><FONT color=red>Permission denied!</FONT>", 2)
       AddInfo("<FONT color=red>Check your permissions for this item.</FONT>", 2)
    Else AddInfo("<FONT color=red>Request failed.</FONT>", 
       AddInfo("<FONT color=red>Result = " & Status & ": " & strStatusText</FONT>, 2)
    End If 
    Return Nothing 
End Function 

The result will be an XmlDocument object. 

The function calls another function: SendRequest. This is standard code that will send the WebDAV SEARCH request:

Function SendRequest(ByVal strCommand As String, ByVal strURL As String, ByVal strBody As String, _
        ByRef strStatusText As String, ByRef iStatCode As Integer) As XmlDocument 
    Try 
        ' Create a new CredentialCache object and fill it with the network credentials required to access the server. 
        Dim Username As String = ConfigurationSettings.AppSettings("UserForReadingCalendars") 
        Dim Password As String = ConfigurationSettings.AppSettings("PwdForReadingCalendars") 
        Dim strDomain As String = ConfigurationSettings.AppSettings("WindowsDomain") 
        Dim myCred As New NetworkCredential(Username, Password, strDomain) 
        Dim myUri As System.Uri = New System.Uri(strURL) 
        Dim MyCredentialCache As New CredentialCache MyCredentialCache.Add(myUri, "NTLM", myCred) 
        ' Create the HttpWebRequest object. 
        Dim objRequest As HttpWebRequest = CType(WebRequest.Create(strURL), HttpWebRequest) 
        ' Add the network credentials to the request. 
        objRequest.Credentials = MyCredentialCache 
        ' Specify the method. objRequest.Method = strCommand 
        ' Set Headers objRequest.KeepAlive = True 
        objRequest.Headers.Set("Pragma", "no-cache") 
        objRequest.ContentType = "text/xml" 
        'Set the request timeout to 5 minutes 
        objRequest.Timeout = 300000 
        If (strBody.Length > 0) Then 
            ' Store the data in a byte array 
            Dim ByteQuery() As Byte = System.Text.Encoding.ASCII.GetBytes(strBody) 
            objRequest.ContentLength = ByteQuery.Length 
            Dim QueryStream As Stream = objRequest.GetRequestStream() 
            ' Write the data to be posted to the Request Stream 
            QueryStream.Write(ByteQuery, 0, ByteQuery.Length) 
            QueryStream.Close() 
         End If 
         ' Send the method request and get the response from the server. 
         Dim objResponse As HttpWebResponse = CType(objRequest.GetResponse(), HttpWebResponse) 
         ' Get the Status code iStatCode = objResponse.StatusCode 
         strStatusText = objResponse.StatusDescription 
         ' Get the XML response stream. 
         Dim ResponseStream As System.IO.Stream = objResponse.GetResponseStream() 
         ' Create the XmlDocument object from the XML response stream. 
         Dim ResponseXmlDoc As New System.Xml.XmlDocument 
         ResponseXmlDoc.Load(ResponseStream) 
         ' Clean up. ResponseStream.Close() 
         objResponse.Close() 
         Return ResponseXmlDoc 
     Catch ex As Exception 
         ' Catch any exceptions. Any error codes from the method requests on the server will be caught here, also. 
         AddInfo("& ex.ToString &"", 2) 
     End Try 
     Return Nothing 
 End Function 

Finally, all the results are brought together in a DataTable object, and presented in a schedule with our ScheduleGeneral custom control. The control will do all the work, we just bind it to the DataTable.

Points of interest

The project is an example of how to retrieve a list of Outlook calendar events from an Exchange server with WebDAV.

History

This is the first version 1.0.