Thursday, September 02, 2004

Processing Meeting requests remotely with WebDAV and OWA

This was something interesting I learned this week. If you want to process meeting requests remotely the same way you can locally with CDOEX then using a combination of WebDAV and some OWA commands can make this happen.

Process the request

Basically when someone invites you to a meeting you will get sent a calendar message that contains all the invitation information. You can differentiate this from a normal message by looking at the DAV:Contentclass and seeing if its set to urn:content-classes:calendarmessage. Now if you want to scan a inbox for any of these messages you could do a WebDAV search against that mailbox for any messages that have this particular content class and also who’s outlookmessage class was set to IPM.Schedule.Meeting.Request which delineates this as a meeting request. Eg

server = "servername"
mailbox = "mailbox"
strURL = "http://" & server & "/exchange/" & mailbox & "/inbox/"
strQuery = ""
strQuery = strQuery & "SELECT ""DAV:href"", ""http://schemas.microsoft.com/exchange/outlookmessageclass"""
strQuery = strQuery & " FROM scope('shallow traversal of """
strQuery = strQuery & strURL & """') Where ""DAV:ishidden"" = False AND ""DAV:isfolder"" = False AND "
strQuery = strQuery & """DAV:contentclass"" = 'urn:content-classes:calendarmessage'
"
set req = createobject("microsoft.xmlhttp")
req.open "SEARCH", strURL, false
req.setrequestheader "Content-Type", "text/xml"
req.setRequestHeader "Translate","f"
req.send strQuery
If req.status >= 500 Then
wscript.echo "Status: " & req.status & " Status text: An error occurred on the server."
ElseIf req.status = 207 Then
wscript.echo "Status: " & req.status & " Status text: An error occurred on the server."
set oResponseDoc = req.responseXML
set oNodeList = oResponseDoc.getElementsByTagName("a:href")
set oclasslist = oResponseDoc.getElementsByTagName("d:outlookmessageclass")
For i = 0 To (oclasslist.length -2)
set oNode1 = oclasslist.nextNode
set oNode = oNodeList.nextNode
if oNode1.Text = "IPM.Schedule.Meeting.Request" then acceptcalmess(oNode.Text)
Next
Else
wscript.echo "Status: " & req.status & " Status text: An error occurred on the server."
End If

sub acceptcalmess(objhref)
wscript.echo objhref
end sub

Now to process the calendar messages this is where you can use the OWA accept and decline commands. Once you issue one of these commands OWA will create a new calendar response message saying that you have accepted or declined this meeting and save this into your drafts folder (the original calendar request message is also deleted). To send this message all you then need to do is move it to the DavMailSubmissionURI. To put this all together with the search example it would look like this

server = "servername"
mailbox = "mailbox"
strURL = "http://" & server & "/exchange/" & mailbox & "/inbox/"
strQuery = ""
strQuery = strQuery & "SELECT ""DAV:href"", ""http://schemas.microsoft.com/exchange/outlookmessageclass"""
strQuery = strQuery & " FROM scope('shallow traversal of """
strQuery = strQuery & strURL & """') Where ""DAV:ishidden"" = False AND ""DAV:isfolder"" = False AND "
strQuery = strQuery & """DAV:contentclass"" = 'urn:content-classes:calendarmessage'
"
set req = createobject("microsoft.xmlhttp")
req.open "SEARCH", strURL, false
req.setrequestheader "Content-Type", "text/xml"
req.setRequestHeader "Translate","f"
req.send strQuery
If req.status >= 500 Then
wscript.echo "Status: " & req.status
wscript.echo "Status text: An error occurred on the server."
ElseIf req.status = 207 Then
wscript.echo "Status: " & req.status
wscript.echo "Status text: " & req.statustext
set oResponseDoc = req.responseXML
set oNodeList = oResponseDoc.getElementsByTagName("a:href")
set oclasslist = oResponseDoc.getElementsByTagName("d:outlookmessageclass")
For i = 0 To (oclasslist.length -2)
set oNode1 = oclasslist.nextNode
set oNode = oNodeList.nextNode
if oNode1.Text = "IPM.Schedule.Meeting.Request" then acceptcalmess(oNode.Text)
Next
Else
wscript.echo "Status: " & req.status
wscript.echo "Status text: " & req.statustext
wscript.echo "Response text: " & req.responsetext
End If

sub acceptcalmess(objhref)

Req.open "GET", objhref & "?cmd=Accept", false
Req.send
wscript.echo req.status
sDestinationURL = "http://" & server & "/exchange/" & mailbox & "/##DavMailSubmissionURI##/"
sSource = replace(lcase(objhref),"/inbox/","/drafts/")
req.open "MOVE", sSource, False
req.setRequestHeader "Destination", sDestinationURL
req.setRequestHeader "Content-Type", "message/rfc822;"
req.setRequestHeader "Translate", "f"
req.setRequestHeader "Content-Length:", Len(xmlstr)
req.send(xmlstr)
wscript.echo req.status
end sub

The last thing you might want to do in regards to processing calendar messages is to process that actual responses that come back from people so that the attendee status in the appointment is updated with accepted, rejected and any new attendees that are invited. To do this all you need to do is open the responses with the open cmd from OWA and OWA will process the request and update the meeting appropriately. To identify the response calendar messages from a request calendar messages you can use the Oulookmessageclass and see if its of type IPM.Schedule.Meeting.Resp.Pos, IPM.Schedule.Meeting.Resp.Neg, IPM.Schedule.Meeting.Resp.Tent .

server = "servername"
mailbox = "username"
strURL = "http://" & server & "/exchange/" & mailbox & "/inbox/"
strQuery = ""
strQuery = strQuery & "SELECT ""DAV:href"", ""http://schemas.microsoft.com/exchange/outlookmessageclass"""
strQuery = strQuery & " FROM scope('shallow traversal of """
strQuery = strQuery & strURL & """') Where ""DAV:ishidden"" = False AND ""DAV:isfolder"" = False AND "
strQuery = strQuery & """DAV:contentclass"" = 'urn:content-classes:calendarmessage'
"
set req = createobject("microsoft.xmlhttp")
req.open "SEARCH", strURL, false
req.setrequestheader "Content-Type", "text/xml"
req.setRequestHeader "Translate","f"
req.send strQuery
If req.status >= 500 Then
wscript.echo "Status: " & req.status
wscript.echo "Status text: An error occurred on the server."
ElseIf req.status = 207 Then
wscript.echo "Status: " & req.status
wscript.echo "Status text: " & req.statustext
set oResponseDoc = req.responseXML
set oNodeList = oResponseDoc.getElementsByTagName("a:href")
set oclasslist = oResponseDoc.getElementsByTagName("d:outlookmessageclass")
For i = 0 To (oclasslist.length -2)
set oNode1 = oclasslist.nextNode
set oNode = oNodeList.nextNode
select case oNode1.Text
case "IPM.Schedule.Meeting.Resp.Neg" acceptcalmess(oNode.Text)
case "IPM.Schedule.Meeting.Resp.Tent" acceptcalmess(oNode.Text)
case "IPM.Schedule.Meeting.Resp.Pos" acceptcalmess(oNode.Text)
end select
Next
Else
wscript.echo "Status: " & req.status
wscript.echo "Status text: " & req.statustext
wscript.echo "Response text: " & req.responsetext
End If

sub acceptcalmess(objhref)

Req.open "GET", objhref & "?cmd=Open", false
Req.send
wscript.echo req.status
end sub



Note processing the meeting responses this way does not delete the response you have to do this manually.

What about task requests?
Task requests seem to be a little different OWA for example doesn’t give you the option to process task requests. So this method is really not applicable.

7 comments:

Anonymous said...

Cool stuff :o)

I've almost got it working! Getting a bleeding Bad Gateway error :(

If you encountered this on your travels, can you enlighten me?

Asher
asher.hudson@ntu.ac.uk

Glen said...

A 502 Bad Gateway sounds like you maybe trying to move the message across the boundaries of a mailbox. What I mean by this is with WebDAV and ADO you can only copy and move items within the same mailbox. If you tried to move the mail from the drafts folder of one mailbox to the mail submission URI of another mailbox this is the type of error you would get.

Cheers
Glen

Anonymous said...

Hi glen

Thanks for the spark i needed!

The submission URI is the draft folder of my inbox! (it's my account that the original calendar request is created)

Now i understand :) thanks very much!

Asher

Anonymous said...

Work like a charm. Thanks a lot for this useful topic.

Although this works already, I cannot resist to ask. Is it possible to do the same using ONLY webdav?

Regards,
Ward

Glen said...

Yes you can but you would need to do everything manually. Eg create the appointment from the request, send any responses etc. You however may run into problems when you start having recurring meeting that might have exceptions which WebDAV can really handle.Also dealing with things like resources is quite hard in WebDAV.

Cheers
Glen

Bhuban said...

Can I create a MeetingRequest Item manually through Code (C# and EWS API)? When I create a EmailMessage and cast it into MeetingRequest, it gives me an Invalid Cast exception.

--
Thanks,
Bhuban
bhubanmmishra@gmail.com

Glen said...

See http://msdn.microsoft.com/en-us/library/dd633661%28EXCHG.80%29.aspx

Cheers
Glen