void Application_PreRequestHandlerExecute(object sender, EventArgs e)
    {
        HttpApplication app = sender as HttpApplication;

        string acceptEncoding = app.Request.Headers["Accept-Encoding"];
        System.IO.Stream prevUncompressedStream = app.Response.Filter;

        if (!(app.Context.CurrentHandler is Page ||
            app.Context.CurrentHandler.GetType().Name == "SyncSessionlessHandler") ||
            app.Request["HTTP_X_MICROSOFTAJAX"] != null)
            return;

        if (acceptEncoding == null || acceptEncoding.Length == 0)
            return;

        acceptEncoding = acceptEncoding.ToLower();

        if (acceptEncoding.Contains("deflate") || acceptEncoding == "*")
        {
            // defalte
            //app.Response.Filter = new System.IO.Compression.DeflateStream(prevUncompressedStream,System.IO.Compression.CompressionMode.Compress);
            app.Response.AppendHeader("Content-Encoding", "deflate");
        }
        else if (acceptEncoding.Contains("gzip"))
        {
            // gzip
            app.Response.Filter = new System.IO.Compression.GZipStream(prevUncompressedStream,System.IO.Compression.CompressionMode.Compress);
            app.Response.AppendHeader("Accept-Encoding", "gzip");
        }
    }