Everything you’d know about state machine for interviews

Less expecting, more accepting.

State Machine Summary

Why State machine

State machines are powerful because behaviour is always guaranteed to be consistent, making it relatively easy to debug.

This is because operational rules are written in stone when the machine is started.

Interaction with state machine

You can interact with the state machine by sending an event, listening for changes or simply request a current state.

Persist StateMachine

One key point is you have to persist StateMachineContext rather than StateMachine

StateMachinePersister vs StateMachinePersist

For StateMachinePersist, it handling serialization logic of a StateMachineContext. You need to implement at least two methods, read and write

While for StateMachinePersister, persisting and restoring a StateMachine from a persistent storage.

One of it’s implementation, DefaultStateMachinePersister which just a default wrapper of AbstractStateMachinePersister,. It’s Constructor accept one instance of StateMachinePersist, and for the method persiste and restore, they are actually invoke read and write from underlying StateMachinePersist.

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