void OnBeginRequest (object o, EventArgs args)
{
HttpApplication application = (HttpApplication) o;
HttpContext context = application.Context;
string file_path = context.Request.FilePath;
string base_path = VirtualPathUtility.GetDirectory (file_path);
string id = UrlUtils.GetSessionId (base_path);
if (id == null)
return;
string new_path = UrlUtils.RemoveSessionId (base_path, file_path);
context.Request.SetFilePath (new_path);
context.Request.SetHeader (HeaderName, id);
context.Response.SetAppPathModifier (id);
}