Dealing with Stateful Communications

The cluster module doesn’t work well with stateful communications where the application state isn’t shared between the various instances. This is because different requests belonging to the same stateful session may potentially be handled by a different instance of the application. This isn’t a problem limited only to the cluster module, but, in general, it applies to any kind of stateless, load-balancing algorithm. Consider, for example, the situation described in the illustration below.