> Stateful servers run into huge problems when other people try to access them from non-static ip (usually sticky sessions are IP based). We, at least in apps I

> Stateful servers run into huge problems when other people try to access them from non-static ip (usually sticky sessions are IP based). We, at least in apps I work on, stuff all the shared state into JWT tokens to avoid this. They're not saying that an application server should never query another server, they're saying that the server that functions as a state container should host a domain-specific api for manipulating the state. See figure 2 b; the frontend and stateful application server layers are separate layers.