Trying to use HttpWebRequest to load a page in a file

I have 开发者_开发知识库a ASP.NET MVC app that works fine in the browser.

I am using the following code to be able to write the html of a retrieved page to a file. (This is to use in a PDF conversion component)

But this code errors out continually but not in the browser.

I get timeout errors sometimes asn 500 errors.

Public Function GetPage(ByVal url As String, ByVal filename As String) As Boolean

        Dim request As HttpWebRequest
        Dim username As String
        Dim password As String
        Dim docid As String
        Dim poststring As String
        Dim bytedata() As Byte
        Dim requestStream As Stream

        Try
            username = "pdfuser"
            password = "pdfuser"
            docid = "docid=inv12154"
            poststring = String.Format("username={0}&password={1}&{2}", username, password, docid)
            bytedata = Encoding.UTF8.GetBytes(poststring)

            request = WebRequest.Create(url)
            request.Method = "Post"
            request.ContentLength = bytedata.Length
            request.ContentType = "application/x-www-form-urlencoded"
            requestStream = request.GetRequestStream()
            requestStream.Write(bytedata, 0, bytedata.Length)
            requestStream.Close()
            request.Timeout = 60000

            Dim response As HttpWebResponse
            Dim responseStream As Stream
            Dim reader As StreamReader
            Dim sb As New StringBuilder()
            Dim line As String = String.Empty

            response = request.GetResponse()
            responseStream = response.GetResponseStream()

            reader = New StreamReader(responseStream, System.Text.Encoding.ASCII)

            line = reader.ReadLine()
            While (Not line Is Nothing)
                sb.Append(line)
                line = reader.ReadLine()
            End While

            File.WriteAllText(filename, sb.ToString())


        Catch ex As Exception
            MsgBox(ex.Message)
        End Try
        Return True

    End Function

I would recommend you simplifying your code and disposing disposable resources such as streams and stream readers. You could also use WebClient:

Using client = New WebClient()
    Dim values = New NameValueCollection()
    values.Add("username", "pdfuser")
    values.Add("password", "pdfuser")
    values.Add("docid", "inv12154")
    Dim result = client.UploadValues(url, values)
    File.WriteAllBytes(filename, result)
End Using