Validating XML fragment against schema

[teclioness]

Hi,

I am finding diffcult to validate a xml fragment to validate against a schema.
The situation is as follows:

I am making an xml string on the fly, but before submitting it to another server, I need to validate that it is a valid xml against schema. I have the schema saved locally on the server. Here is the xml:

<?xml version='1.0' encoding='UTF-8'?>
<portalReq xmlns='http://www.e-paycapita.com/portal'>
<requestID>1234</requestID>
<language>en</language>
<source>l</source>
<returnURL>http://www.portsmouth.gov.uk</returnURL>
<backURL>http://bbc.co.uk</backURL>
<cart>
<items><item itemNumber='1'>
<reference>CTax123</reference>
<fundCode>05</fundCode>
<accountName>Mr. A J Kaul</accountName>
<amount>112.56</amount>
</item>
</items>
</cart>
</portalReq>

I have attached the schema file as .txt with this post.
I have come across XmlValidatingReader class and tried to use it, but even if I take out one required element from xml, it does not produce error: Following is the code:

Private Function ValidateXML(ByVal objStr As StringReader)
        Dim reader As XmlValidatingReader = Nothing
        Dim myschema As New XmlSchemaCollection

        Try
            'Create the XML fragment to be parsed.
            Dim xmlFrag As String = objStr.ReadToEnd

            'Create the XmlParserContext.
            Dim context As New XmlParserContext(Nothing, Nothing, "", XmlSpace.None)

            'Implement the reader.
            reader = New XmlValidatingReader(xmlFrag, XmlNodeType.Element, context)

            'Add the schema.
            Dim strXSD As String = Server.MapPath("abc.xsd")
            myschema.Add("http://www.abc.com/abc", strXSD)

            'Set the schema type and add the schema to the reader.
            reader.ValidationType = ValidationType.Schema
            reader.Schemas.Add(myschema)

            'Add the handler to raise the validation event.
            AddHandler reader.ValidationEventHandler, AddressOf Me.ValidationEventHandle

            While reader.Read
            End While
            Label1.Text = Label1.Text + "Completed validating xmlfragment"

        Catch XmlExp As XmlException
            Label1.Text = Label1.Text + XmlExp.Message
        Catch XmlSchExp As XmlSchemaException
            Label1.Text = Label1.Text + XmlSchExp.Message
        Catch GenExp As Exception
            Label1.Text = Label1.Text + GenExp.Message
        End Try
    End Function
    Public Sub ValidationEventHandle(ByVal sender As Object, ByVal args As ValidationEventArgs)
        m_success = False
        Console.WriteLine((ControlChars.CrLf & ControlChars.Tab & "Validation error: " & args.Message))
    End Sub 'ValidationEventHandle
    Private Function validateXML(ByVal xml As String)
        Try
            'Is the xml string valid?
            If (xml Is Nothing Or xml.Length < 1) Then
                Return False
            End If

            Dim srXml As StringReader = New StringReader(xml)
            Return validateXML(srXml)
        Catch ex As Exception
            ValidationError = ex.Message
            Return False
        End Try
    End Function
    Public Property ValidationError()
        Get
            Return "<ValidationError>" + ValidationError + "</VALIDATIONERROR>"
        End Get
        Set(ByVal Value)
            ValidationError = Value
        End Set
    End Property
    Public Sub validationCallBack(ByVal sender As Object, ByVal args As ValidationEventArgs)
        Label1.Text = "Error:" + args.Message
    End Sub

Please help!!