Public Function validieren(ByVal file As String) As String
 
Dim result As String
Dim resulterrors As String
 
Dim header As String
 
'reset UI information 
[error] = ""
result = ""
resulterrors = ""
isValid = True
header = ""
 
Dim xml As New XmlTextReader(file)
Dim xsd As New XmlValidatingReader(xml)
'xml.XmlResolver = 
Try
 
xsd.ValidationType = ValidationType.Schema
 
'and validation errors events go to... 
AddHandler xsd.ValidationEventHandler, AddressOf MyValidationEventHandler
 
'wait until the read is over, its occuring in a different thread - kinda like 
' when your walking to get a cup of coffee and your mind is in Hawaii 
While xsd.Read()
End While
 
' Check whether the document is valid or invalid. 
If isValid Then
header = "Document is valid"
Else
header = "Document is invalid"
End If
Catch a As UnauthorizedAccessException
'dont have access permission 
[error] = a.Message
Catch a As Exception
'and other things that could go wrong 
[error] = a.Message
Finally
    'Close the reader.
    If Not (xsd Is Nothing) Then
        xsd.Close()
    End If
 
End Try
resulterrors = [error]
result = header
If InStr(result, "is valid") <> 0 Then
    validieren = ""
Else
    validieren = "Result:" & result & vbCrLf & "Resulterrors:" & resulterrors
End If
End Function
'handle our validation errors
Public Sub MyValidationEventHandler(ByVal sender As Object, ByVal args As _
  System.Xml.Schema.ValidationEventArgs)
    isValid = False
    'MsgBox("Exception=" & args.Exception.ToString & vbCr & "Message=" & 
    ' args.Message & "Severity=" & args.Severity)
    [error] += args.Message + ControlChars.Lf + ControlChars.Lf
End Sub 'MyValidationEventHandler

Private Function Schema_Pruefung(ByVal strXML As String) As Boolean
    ' Variablendeklaration
    Dim XMLSchema As Object
    Dim XMLdom As Object
    Dim blnRueckgabe As Boolean
    Dim fso As Scripting.FileSystemObject
    ' Fehlerbehandlung
    On Error GoTo fehler
    ' Variableninitialisierung
    blnRueckgabe = True
    ' Objektinstanzierung
    Set XMLSchema = CreateObject("Msxml2.XMLSchemaCache.4.0")
    Set XMLdom = CreateObject("Msxml2.DOMDocument.4.0")
    Set fso = CreateObject("Scripting.FileSystemObject")
 
    ' Schemaprüfung
    ' XML-Daten aus Temp-Datei (über XSD-Schema) in DOM einlesen
    XMLdom.async = False
    XMLdom.validateOnParse = True
    XMLdom.Load (strXML)
 
    ' Schema-Prüfung
    If XMLdom.parseError.errorcode <> 0 Then
        ' Fehlermeldung
        blnRueckgabe = False
        MsgBox ("Errorcode=" & XMLdom.parseError.errorcode)
        ' XML_Fehler XMLdom.parseError
    End If
 
    ' XML-Objekte zerstören
    Set XMLdom = Nothing
    Set XMLSchema = Nothing
    ' Objekt zerstören
    Set fso = Nothing
    ' Rückgabe
    Schema_Pruefung = blnRueckgabe
    Exit Function
' Fehlerbehandlung
fehler:
    ' Rückgabe
    Schema_Pruefung = False
End Function