Question

I’m attempting to update a legacy VB6 component (not written by me) to the .NET platform. There is one function which posts an XML string to a URL:

Function PostToUrl(ByRef psUrl, ByRef psData, Byref psResponseText, ByRef psErrorMsg, ByRef psUsername, ByRef psPassword)

    On Error Resume Next    
    Dim objWinHTTP

    PostToUrl = False
    psErrorMsg = ""
    psResponseText = ""
    Dim m_lHTTPREQUEST_SETCREDENTIALS_FOR_SERVER
    m_lHTTPREQUEST_SETCREDENTIALS_FOR_SERVER    =0  

    Set objWinHTTP = CreateObject("WinHttp.WinHttpRequest.5.1")


    objWinHTTP.Open "POST", psUrl

    If psUsername <> "" Then
        Call objWinHTTP.SetCredentials(psUsername, psPassword, m_lHTTPREQUEST_SETCREDENTIALS_FOR_SERVER)
    End If
    objWinHTTP.SetRequestHeader "Host", "http://www.xxx.com/CSIHTTP.asp"
    objWinHTTP.SetRequestHeader "X-Method", "Submit"
    objWinHTTP.SetRequestHeader "Content-Type", "text/xml"

    objwinHTTP.setTimeouts 3000, 15000, 15000, 120000


    Call objWinHTTP.Send(psData)

    ' Handle errors  '


    If Err.Number <> 0 Then

        psErrorMsg = Err.Description & " test"
        PostToUrl = False

    ElseIf objWinHTTP.Status <> 200 AND objWinHTTP.Status <> 202 Then

        psErrorMsg = "(" & objWinHTTP.Status & ") " & objWinHTTP.StatusText
        PostToUrl = False

    Else

        psErrorMsg = objWinHTTP.ResponseText & "(" & objWinHTTP.Status & ") " & objWinHTTP.StatusText
        PostToUrl = True

    End If

    Set objWinHTTP = Nothing
End Function

I’ve updated this to:

Public Function PostXml(ByVal XML As String) As Boolean

        Try
            Dim URL As String = My.Settings.NTSPostURL 
            'TODO: supply username and password!  '
            Dim Bytes As Byte() = Me.Encoding.GetBytes(XML)
            Dim HTTPRequest As HttpWebRequest = DirectCast(WebRequest.Create(Me.PostURL), HttpWebRequest)
            Dim Cred As New NetworkCredential("username", "password", "http://www.xxx.com")

            With HTTPRequest
                .Method = "POST"
                .ContentLength = Bytes.Length
                .ContentType = "text/xml"
                .Credentials = Cred
                .Timeout = 120000
                .Method = "Submit"
            End With

            Using RequestStream As Stream = HTTPRequest.GetRequestStream()
                RequestStream.Write(Bytes, 0, Bytes.Length)
                RequestStream.Close()
            End Using

            Using Response As HttpWebResponse = DirectCast(HTTPRequest.GetResponse(), HttpWebResponse)

                If Response.StatusCode <> HttpStatusCode.OK Then

                    Dim message As String = [String].Format("POST failed. Received HTTP {0}", Response.StatusCode)

                    Throw New ApplicationException(message)

                End If

            End Using

        Catch ex As WebException
            Dim s As String = ex.Response.ToString() & " " & ex.Status.ToString()
            Throw
        End Try

    End Function

However when I run the .NET code the server returns the error ‘403 Forbidden – protocol error’ on the line:
Using Response As HttpWebResponse = DirectCast(HTTPRequest.GetResponse(), HttpWebResponse)
. The VB6 code runs fine. Can anyone identify any discrepancies between the two that might be causing this? It’s left me stumped….

Answer 1

After much pain I’ve finally managed to get it working. Problem was with the text encoding, I’ve changed it to ASCII and it all works:

Try
            Dim Bytes As Byte() = Me.Encoding.GetBytes(XML)
            Dim HTTPRequest As HttpWebRequest = DirectCast(WebRequest.Create(Me.PostURL), HttpWebRequest)

            With HTTPRequest
                .Method = "POST"
                .ContentLength = Bytes.Length
                .ContentType = "text/xml"
                .Credentials = New NetworkCredential("user", "password") 'myCache
            End With

            Using RequestStream As Stream = HTTPRequest.GetRequestStream()
                RequestStream.Write(Bytes, 0, Bytes.Length)
                RequestStream.Close()
            End Using

            Using Response As HttpWebResponse = DirectCast(HTTPRequest.GetResponse(), HttpWebResponse)

                Return Response.StatusCode

            End Using

        Catch ex As WebException
            Dim s As String = ex.Status.ToString
            Throw
        End Try

Thanks to all who helped. Upvotes all round.