How to make a state available to all beans in a "session"?

Question

I have the following design. When a client makes a request to the server, the server creates a state that holds all sorts of info. There are various stateless and stateful beans which need to read and write to this state. Refer to this unprofessional diagram:

The ComputationCycle class is where the processing starts and works by phases. During each phase it calls upon other Manager classes (which behave like utility classes) to help in the computation (diagram shows only for 1 phase). The state is being read and written to both from the CC class and the managers, both are stateless.

State holds Employee, Department and Car classes (in some irrelevant data structure) which are stateful. These classes can also call the Manager classes. This is done by a simple @Inject Manager1. The same way CC uses managers.

My problem is how to access the stateful state (and its contained classes) from the stateless classes (and from the Car, Department and Employee classes too, although I think solving one will solve the other). I can't inject a stateful bean into a stateless bean. So after the client makes a request and the computation cycle starts, how do I access the state related to this request?

One solution is to pass the state to every method in the stateless classes, but this is really cumbersome and bloaty because all methods will have an "idiotic" State argument everywhere.

How can I make this design work the way I want it to?

Answer 1

I can't inject a stateful bean into a stateless bean.

You can absolutely inject dependencies this way.

If the stateful bean is @RequestScoped, any call into the stateless bean on that thread that hits a CDI injected contextual reference (iow proxy) will find its way to the right instance of the stateful bean.

As long as you use CDI, you don't need to trouble yourself with trying to stash things away in your own threadlocals.