How to make sure httpwebrequest/response is cleared on each fetch?

[p_nivalis]

I am wondering if there is a way to be 100% certain the httpwebrequest/response is cleared so that each time it retrieves the web source, it is fresh source and not cached (or old)?

Here is the code I am currently using:

    Public Function GetDataFromURL(ByVal sURL As String) As String

        GetDataFromURL = String.Empty

        Debug.Print("*GetDataFromUrl: started")
        Dim NewHTML As String = String.Empty

        sURL = Trim(sURL)

        Try

            Dim oReq As System.Net.HttpWebRequest
            Dim oResp As System.Net.HttpWebResponse

            oReq = System.Net.HttpWebRequest.Create(sURL)

            With oReq
                .Referer = RandomReferer()
                .UserAgent = RandomUserAgent()
                .Timeout = 30000
                .KeepAlive = False
                .AllowWriteStreamBuffering = True
            End With

            oResp = oReq.GetResponse

            Dim sr As New IO.StreamReader(oResp.GetResponseStream)
            Return sr.ReadToEnd

        Catch ex As Net.WebException

            Debug.Print("*WebException: " & ex.Message)

            If ex.Status = Net.WebExceptionStatus.ProtocolError Then

                Debug.Print("*Status Code: {0}", CType(ex.Response, Net.HttpWebResponse).StatusCode)
                Debug.Print("*Status Description: {0}", CType(ex.Response, Net.HttpWebResponse).StatusDescription)

                Dim strError As New System.Text.StringBuilder

                With strError
                    .Append(My.Computer.Clock.LocalTime.ToString.Trim)
                    .Append(": ")
                    .Append(ex.Message.Trim)
                End With

                ' ## Show the user the last 5 errors while attempting to retrieve source (Unfinished)
                'frmMain.ToolStripMenuItem2.Text = strError.ToString
                'frmMain.ToolStripMenuItem2.Image = frmMain.ImageList1.Images(3)

            End If

        Catch ex As Exception

            Return String.Empty
            Debug.Print("*Error Fetching URL Data: " & ex.Message)

        Finally

            Debug.Print("*GetDataFromUrl: ended")

        End Try

    End Function

Thanks in advance

 

[JohnH]

Set the DefaultCachePolicy property for the request, This is an instance of HttpRequestCachePolicy class that can be initialized by the constructor to for example preset values of HttpRequestCacheLevel enumeration. The response can be checked with IsFromCache and LastModified properties to see how updated the returned info is.

I just noticed you're doing VB2003, where this info doesn't appear to be available.

 

[JohnH]

You may be able to set some relevant headers for this, see the RFC about request headers (RFC 2616, HTTP/1.1 protocol). But if you see the WebHeaderCollection docs there are some protected headers that cannot be set, unless they are directly exposed as properties.

 

[p_nivalis]

Thank you John, I will play with what you told me when I get back home.

Sorry about that, I am actually using VS2005. I'm going to go update that now.