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Spring Statemachine

Spring State Machine is a framework within the Spring ecosystem that provides abstractions and tools for building finite state machines (FSMs) in Java applications. Finite state machines are used to model and manage the behavior of systems with discrete states and transitions. Spring State Machine simplifies the development of stateful applications, such as workflow engines, embedded controllers, and process automation systems.

Key features and components of Spring State Machine include:

  • State Configuration: You can define states, transitions, and events in a structured manner using Spring State Machine’s configuration API. States represent the discrete states of your application, transitions define how your application moves from one state to another, and events trigger these transitions.

  • Stateful Logic: You can attach stateful logic to states and transitions, allowing you to execute code when entering, exiting, or staying in a particular state, or when a transition occurs.

  • Hierarchical States:Spring State Machine supports hierarchical states, allowing you to model complex state structures. States can be organized into nested state hierarchies.

  • Choice and Fork States: You can use choice states to make decisions based on conditions, and fork states to create parallel execution paths.

  • Entry and Exit Actions: Define actions that are executed when entering or exiting states. This is useful for initializing or cleaning up resources associated with a state.

  • Guards Attach guards to transitions to make decisions on whether a transition can occur based on conditions or criteria.

  • Persistence: Spring State Machine supports different persistence backends, allowing you to save and restore the state of the state machine. Common persistence options include relational databases, Redis, and in-memory storage.

  • Listeners and Observers: You can register listeners and observers to track state machine events, transitions, and state changes.

  • Error Handling:Spring State Machine provides mechanisms for handling errors and exceptions, including error states and error-handling transitions.

  • Extensibility: The framework is extensible, allowing you to plug in custom implementations for various components, such as state resolvers, persisters, and region factories.

  • Integration with Spring: Spring State Machine seamlessly integrates with other Spring projects, such as Spring Boot, Spring Data, and Spring Integration, making it easier to build end-to-end applications with Spring.
  • Here’s a simplified example of how to create a basic Spring State Machine configuration:

    public class MyStateMachineConfig extends 
    StateMachineConfigurerAdapter<String, String>
        public void configure
        <String, String> transitions)
                throws Exception 

    In this example, a Spring configuration class defines a simple state machine with two states (“START” and “END”) and two transitions triggered by events (“EVENT1” and “EVENT2”).

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