protected abstract Response render (URL url, HostProxy proxy, DBConnect dbc, Request request, InvalidRequest invalid) throws Exception;
protected Response render (Resource r1, Resource r2, Resource r3, Request request, InvalidRequest invalid) throws Exception {
URL url = r1 != null ? ((UrlResource) r1).getUrl(end) : null;
HostProxy proxy = r2 != null ? ((HostProxyResource)r2).getHostProxy() : null;
if (proxy != null) proxy.setLogger(logger);
DBConnect dbc = r3 != null ? ((JDBCResource) r3).getDBConnect() : null;
return render(url, proxy, dbc, request, invalid);
}