@Flow
public class MainFlow {
}

@State(start = true)
public class StartState {

    @Transition
    @Transactional
    public void one() {
    }

    @Transition(to = "end")
    public void end() {
    }
}

@State(end = true)
public class EndState {

    @Transition
    public void one() {
    }

    @Transition(to = "start")
    public void restart(@TransitionArgument int i) {
    }
}

Without giving a detailed explanation, you can follow the annotation and infer that we have a flow with two states (start and end); each state has two transitions. To use this flow, we can use the FlowSession like so:

// instantiate flow with id "main"
FlowInstance instance = flowSession.instantiate("main"); 

// calls StartState.one() and stays in the start state
instance.performTransition("one"); 

// calls StartState.end() and transitions to end state
instance.performTransition("end"); 

// calls EndState.restart(5) and transitions to start state
instance.performTransition("restart", 5);
...

Now, you can ask where we got the names “main”, “one”, “end” and others; I’m sure you can see that the MainFlow class would be the flow with id “main”, but we never said so explicitly in the code. The BeanPostProcessor uses naming strategies that take the ids explicitly set in the annotations or, if the annotation does not have the id set, it takes the class name or the bean name as the identity of the flow, state or transition.
Also, you may notice that the states somehow get attached to the main flow, even though we never defined this. Again, there is a bit of “intelligence” in the module that automatically registers a state with a flow even if no flow id is set if there is only one flow. In more complex applications (ones that use more than one flow), you must explicitly set the flowId value in the @State annotation.
We are going to put much more work into this module, but we can confidently state that the module is an exciting piece of code. The design of the module will allow us to use service orchestration language in the transitions (take a look at the TransitionAction interface and its implementations for a hint of possible solution).

Service Orchestration

The SO module will allow the developers to create a workflow-style structure, where the transitions carry business logic. In the transitions — I’m sure you’ll forgive me for the slightly non-technical description — you will be able to call any number of services; naturally, the transition will be able to participate in a JTA transaction.

Spring AJAX

This is a buzz-word like no other, but it is still very clumsy to create rich applications using the Spring Framework. We propose to create a module that will allow declarative AJAX handling code. The handling code will work with AjaxSessions and JsonViews by default, but there will be nothing stopping you from creating much more complex AJAX handling structures. Along with the Java-side support, we will give you JSP tag libraries to handle all mundane AJAX code.