Unable to Trigger an Event from Action

I am setting up spring state-machine transactions, i want to launch Event2 on completion of Event1

These are the states i have

States -> "INITIAL", "SECOND", "THIRD"

I have configured the transactions to send SECOND_EVENT from action of FIRST_EVENT as shown below

transitions.withExternal()
    .source("INITIAL")
    .target("SECOND")
    .event("FIRST_EVENT")
    .action(new Action<String, String>() {
        @Override
        public void execute(StateContext<String, String> context) {
            System.out.println("FIRST_ACTION_EXECUTED");
            context.getStateMachine().sendEvent("SECOND_EVENT");
        }
    })
    .and()
    .withExternal()
    .source("SECOND")
    .target("THIRD")
    .event("SECOND_EVENT")
    .action(new Action<String, String>() {
        @Override
        public void execute(StateContext<String, String> context) {
            System.out.println("TEST SUCCESS");
        }
    });

Here i get evenNotAccepted exception, and i know the reason is that the statemachine.getState() is INITIAL, and it cant change the state from INITIAL to THIRD directly.

So my question is, Is there anyway that i can configure my statemachine to automatically trigger second event on completion of first event

Solution

It's because of the type of actions you're using. There are two main types of actions in the Spring SM - transition actions and state actions - and they resolve on different times. You can see a sequence of resolving of those actions here.

In order to fire events to go to your next state, you should use state actions.

You can configure state actions like so:

   builder.configureStates()
            .withStates()
            .initial(SI)
            .state(F1, context -> context.getStateMachine().sendEvent(E2))
            .state(F2, context -> context.getStateMachine().sendEvent(E3))
            .end(SF);

    builder.configureTransitions()
            .withExternal().source(SI).target(F1).event(E1)
            .and()
            .withExternal().source(F1).target(F2).event(E2)
            .and()
            .withExternal().source(F2).target(SF).event(E3)
                .action(context -> System.out.println("Completing SM!"));

Just firing event E1 manually, will result in the following output (events E2 and E3 are auto-fired through state actions):

STATE ENTERED: SI
STAGE TRANSITIONS From: null To: SI
STATE EXITED: SI
STATE ENTERED: F1
STAGE TRANSITIONS From: SI To: F1
21:45:39.153 [pool-2-thread-1] DEBUG org.springframework.statemachine.support.AbstractStateMachine - Queue event GenericMessage [payload=E2, headers={id=393a5636-a760-57d6-a98b-d31eb75f048e, timestamp=1560969939152}] SF F2 F1 SI  / F1 / uuid=4e8773c1-e755-40de-b431-e53a4b0ca64d / id=null
STATE EXITED: F1
STATE ENTERED: F2
STAGE TRANSITIONS From: F1 To: F2
21:45:39.161 [pool-2-thread-1] DEBUG org.springframework.statemachine.support.AbstractStateMachine - Queue event GenericMessage [payload=E3, headers={id=f5899e8b-e4a5-e079-3a30-66114a7accac, timestamp=1560969939161}] SF F2 F1 SI  / F2 / uuid=4e8773c1-e755-40de-b431-e53a4b0ca64d / id=null
Completing SM!
STATE EXITED: F2
STATE ENTERED: SF
STAGE TRANSITIONS From: F2 To: SF