Spring State Machine Example Project

This project serves as an example of using Spring State Machine to implement a simple use case. The use case involves creating a state machine, passing variables through the context, resetting the state machine to a specific state, and sending events.

The project is built with Java 17 and uses Spring State Machine version 4.0.0.

• Java 17
• Maven
• Spring State Machine 4.0.0

1. Clone the repository:

   git clone https://github.com/heyuall/spring-state-machine-demo.git

2. Build the project:

   mvn clean install

1. State Machine Config (StateMachineConfig.java): This configuration class uses StateMachineFactory to configure the state machine. This approach is suitable when dealing with multiple state machines, allowing for effective lifecycle management.

2. State Machine Persistence Config (StateMachinePersistenceConfiguration.java): This configuration class focuses on state machine persistence. It utilizes JpaPersistingStateMachineInterceptor to persist the state machine context, storing it in the automatically created "state_machine" table.

3. State Machine Service Config (StateMachineServiceConfig.java): This configuration class is responsible for setting up the state machine service. It wires up the StateMachineFactory and StateMachineRuntimePersister to create a DefaultStateMachineService that manages state machines.

This service, implemented in StateMachineUseCaseExampleService, demonstrates a simple use case using Spring State Machine. The steps are as follows:

1. Instantiate State Machine:

   • Acquires a new state machine instance from the StateMachineService using acquireStateMachine.
   • Generates a unique identifier for the state machine.

2. Pass Variables to Context:

   • Creates a map of variables, e.g., machineIdentifier, to be passed through the state machine context.
   • Sets these variables in the state machine's extended state for potential retrieval during transitions.

3. Force Reset to a Specific State:

   • Utilizes resetStateMachineReactively to forcefully reset the state machine to a designated state (e.g., States.THIRD).
   • This action effectively places the state machine in a predetermined state, ready for further processing.

4. Resume by Sending an Event:

   • Sends an event (e.g., Events.END) to the state machine using sendEvent.
   • This step demonstrates a transition to the end state.

5. Note on Resuming:

   • A comment indicates that attempting to resume the state machine after reaching the end state may not be allowed, as it's already at the last state.

6. Run the Use Case:

   • The use case is initiated on application start by implementing CommandLineRunner and calling stateMachineUseCase.

These steps illustrate a basic flow in working with Spring State Machine, involving instantiation, context manipulation, state resetting, and event triggering.

The state machine is created, and the use case is executed when the application starts.
The CommandLineRunner implementation in StateMachineUseCaseExampleService initiates the use case.

The state machine context is automatically persisted in the state_machine table, which is created by Spring State Machine.

To run the application, execute:

java -jar target/stateMachineDemo0.0.1-SNAPSHOT.jar