This Spring Web Flow (SWF) sample application illustrates:
Use of stateful middle-tier components as flow variables to carry out the execution of business logic.
This sample shows how to use SWF to develop such components without coupling your application code to SWF APIs.
Use of custom state exception handlers to handle exceptions.
Use of the evaluate-action to evaluate expressions against the flow request context;
in this example to call the "makeGuess" method on a flow-scoped "game" bean.