I have a web application (.NET 3.5) that has this code in Global.asax:

Sub Application_BeginRequest(ByVal sender As Object, ByVal e As EventArgs)
    LinkLoader()
    PathRewriter()
    PathAppender()
End Sub

I want all those functions inside to get called except for when it's an AJAX call back. So, ideally I would have it changed to:

Sub Application_BeginRequest(ByVal sender As Object, ByVal e As EventArgs)
    If not Page.IsCallback then
        LinkLoader()
        PathRewriter()
        PathAppender()
    End If
End Sub

But there is not access to the page object here. So, basically my question is:

How do I check if the request is an AJAX call back inside Application_BeginRequest?

Thank you very much for any feedback.