How to retrieve an object's security descriptor property by using Visual Basic .NET

Imports System.Net
Imports System.IO

Module Module1
    Sub Main()
        ' TODO: Replace with your object URL.
        Dim sUri As String = "http://ExchServer/Public/MyFolder/Test.EML"

        Dim myUri As System.Uri = New System.Uri(sUri)
        Dim HttpWRequest As HttpWebRequest = WebRequest.Create(myUri)

        Dim strSDType As String = "descriptor"
        Dim sQuery As String
        sQuery = "<?xml version='1.0' encoding='utf-8'?>" & _
         "<propfind xmlns=""DAV:"">" & _
         "<prop xmlns:r=""http://schemas.microsoft.com/exchange/security/"">" & _
         "<isfolder/>" & _
         "   <r:" & strSDType & "/>" & _
         "</prop>" & _
         "</propfind>"

        ' TODO: Replace with the appropriate user credential.
        Dim myCred As NetworkCredential = New NetworkCredential("Domain\UserName", "Password")
        Dim MyCredentialCache As CredentialCache = New CredentialCache()
        MyCredentialCache.Add(myUri, "Basic", myCred)
        HttpWRequest.Credentials = MyCredentialCache

        ' Set headers.
        HttpWRequest.KeepAlive = False
        HttpWRequest.Headers.Set("Pragma", "no-cache")
        HttpWRequest.ContentType = "text/xml"
        HttpWRequest.Headers.Set("Translate", "f")
        HttpWRequest.Headers.Set("Depth", "0")
        HttpWRequest.ContentLength = sQuery.Length

        'Set the request timeout to 5 minutes.
        HttpWRequest.Timeout = 300000
        ' set the request method
        HttpWRequest.Method = "PROPFIND"

        ' Store the data in a byte array.
        Dim ByteQuery() As Byte = System.Text.Encoding.ASCII.GetBytes(sQuery)
        HttpWRequest.ContentLength = ByteQuery.Length
        Dim QueryStream As Stream = HttpWRequest.GetRequestStream()
        ' write the data to be posted to the Request Stream
        QueryStream.Write(ByteQuery, 0, ByteQuery.Length)
        QueryStream.Close()

        ' Send the request and get the response.
        Dim HttpWResponse As HttpWebResponse = HttpWRequest.GetResponse()

        ' Get the status and the headers.
        Dim iStatCode As Integer = HttpWResponse.StatusCode
        Dim sStatus As String = iStatCode.ToString()
        Console.WriteLine("Status: {0} {1}", sStatus, HttpWResponse.StatusDescription.ToString())

        Console.WriteLine("Request Headers:")
        Console.WriteLine(HttpWRequest.Headers.ToString())
        Console.WriteLine("Response Headers:")
        Console.WriteLine(HttpWResponse.Headers.ToString())

        ' Get the response stream.
        Dim strm As Stream = HttpWResponse.GetResponseStream()

        ' Read the response stream.
        Dim sr As StreamReader = New StreamReader(strm)
        Dim sText As String = sr.ReadToEnd()
        Console.WriteLine("Response: {0}", sText)

        ' Close the stream.
        strm.Close()

        ' Clean up
        HttpWRequest = Nothing
        HttpWResponse = Nothing
        MyCredentialCache = Nothing
        myCred = Nothing
        strm = Nothing
        sr = Nothing
    End Sub
End Module