Question

my goal is to track all logged users in my web portal to develop some kind of administration app that provides stats to admin users. I have some idea of how to develop it but I’m not sure if is the right thing to do. Basically a listener will put a custom some object inside the servlet context and the login servlet will fill it with user information every time a user logs in and out and other information.

Thank you even if you only read it!

Answer 1

In fact, you always keep session data somewhere inside your application context. It’s up to you where to keep it, depending on the workload – you may keep it either in the servlet itself (meaning its own memory) or somewhere else (for example, in a dedicated database).
Choosing second option will cause you to use additional interfaces and data transfers (between your servlet and the DB), but it’s much more scalable and is the best option for huge workloads.
Simply, if you have 10 active sessions and high activity, you better use local memory. If you have 100k+ active sessions and low activity – some shared resource is your choice.
It is optimal for you to start with local memory and then perform some load testing to determine if you need a separate data domain for the sessions.