PHP objects are not persistent. On ajax call, the server accepts info without any hangover - i.e. info from previous server actions. Session data is available though, but that's hardly the same as the data is usually in a file (or DB). You can set objects to be persistent, but that's a pretty big consideration. PHP is build up, tear down. So, without object persistence or storing the state of dead objects in sessions, you need to create all your objects from scratch.