protected void ButtonLogin_Click(object sender, EventArgs e)
        {
            User usr   = UserDataProcess.controlUser(TextBoxLoginNick.Text, InputLoginPassword.Value);
            User admin = AdminDataProcess.controlAdmin(TextBoxLoginNick.Text, InputLoginPassword.Value);

            LabelNoUser.Text = "";
            if (usr != null)
            {
                if (admin != null)
                {
                    Session["AuthenticatedAdminData"] = admin;
                    UserDataProcess.UpdateUserOnline(admin.UserId, true);
                }
                else
                {
                    Session["AuthenticatedUserData"] = usr;
                    UserDataProcess.UpdateUserOnline(usr.UserId, true);
                }
                Response.Redirect("HomeLibrary.aspx");
            }
            else
            {
                LabelNoUser.Text = "No Authentication!";
            }
        }
        protected void ButtonLogOut_Click(object sender, EventArgs e)
        {
            if (Session["AuthenticatedUserData"] != null)
            {
                User user = (User)Session["AuthenticatedUserData"];
                UserDataProcess.UpdateUserOnline(user.UserId, false);
            }
            else if (Session["AuthenticatedAdminData"] != null)
            {
                User admin = (User)Session["AuthenticatedAdminData"];
                UserDataProcess.UpdateUserOnline(admin.UserId, false);
            }

            Session["AuthenticatedUserData"]  = null;
            Session["AuthenticatedAdminData"] = null;
            ButtonLogOut.Visible = false;
            ButtonLogIn.Visible  = true;
            LinkButton1.Visible  = false;
            ButtonOrder.Visible  = false;
            Response.Redirect("Default.aspx");
        }