Lightweight Mini-FSM

更多详情参考：https://cloud.tencent.com/developer/article/2418561

Background

Based on the design concepts of Cola StateMachine and Spring StateMachine, the design has been simplified and the ActionResult returned after the execution of Action has been expanded. The execution of Action uses reactive programming, implemented based on Flux and Mono. The main interface definitions of the Mini-FSM finite state machine include:

• StateMachine: This maintains the context of the state machine.
• StateMachineEventResult: The return result of the state machine event transition, including obtaining the current state, Action results, etc.
• State: This passes event information and is used for state transition. The core processing of FSM, StateContext refers back to the context of the state machine.
• Event: This can be defined based on the enumeration class.
• Action: This corresponds to the specific event execution processing.
• ActionResult: The return result of event execution, encapsulating the details of the result.
• Guard: The condition, indicating whether it is allowed to reach a certain state.
• Transition: The transition, indicating from one state to another, including TransitionKind type, TransitionData data.

The execution characteristics of the Mini-FSM execution framework are:

• Stateless: The Statemachine state machine itself is stateless, with no thread safety issues.
• Lightweight: Ultra-lightweight framework with only three external dependency packages.
• Multiple forms:
  • Execution method: Supports synchronous and asynchronous event triggering.
  • Transition method: Supports internal transition (the current state and the next state remain consistent) and external transition forms.
  • Result return: The triggering of the event allows the return of the Action execution result, and supports obtaining execution time, execution exceptions, and other information.

Architecture

The implementation of the Mini-FSM framework is as follows: Users trigger the current state transition based on the Event event and return the transition result.

• sendEvent: Action accepts the sendEvent request for processing, and encapsulates the transition information for the transit operation.
• transit: Based on TransitionData processing, 1. Verify execution conditions based on Guard; 2. Trigger execution Apply based on Action and return the execution result.

Transition types are divided into two categories:

• EXTERNAL: External transition, where the Event execution changes the state.
• INTERNAL: Internal transition, where the Event execution does not change the state, and the current state and the next state remain consistent. It is a special case of EXTERNAL transition.

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中文文档

背景说明

基于Cola StateMachine 和 Spring StateMachine 的设计思想进行简化，扩展了Action执行后的返回结果ActionResult。其中Action的执行使用响应式编程，基于Flux和Mono实现。Mini-FSM有限状态机的主要接口定义包括：

• StateMachine：状态机，维护状态机的上下文
• StateMachineEventResult：状态机事件转换的返回结果，包括获取当前状态、Action结果等
• State：状态，传递事件信息并用于状态转换，FSM核心处理，StateContext 反向引用状态机的上下文
• Event：事件，可基于枚举类定义
• Action：动作，对应具体事件的执行处理
• ActionResult：事件执行的返回结果，封装结果详情
• Guard：条件，表示是否允许到达某个状态
• Transition：流转，表示从一个状态到另一个状态，包括TransitionKind类型，TransitionData 数据

Mini-FSM执行框架执行特点：

• 无状态: Statemachine状态机本身是无状态（Stateless）的，无线程安全问题
• 轻量级: 超轻量级框架，仅三个外部依赖包
• 多形式：
  • 执行方式：支持同步、异步事件触发
  • 流转方式：支持内部流转(现态与次态保持一致)、外部流转形式
  • 结果返回：事件触发Action执行，允许返回Action执行结果，支持获取执行耗时、执行异常等信息

实现架构

Mini-FSM框架实现如下所示：用户基于Event事件触发当前状态转移并返回转移结果

• sendEvent：Action接受sendEvent请求处理，封装封装transition信息进行transit操作
• transit：基于TransitionData处理，1. 基于Guard校验执行条件；2. 基于Action触发执行Apply并返回执行结果

Transition流转类型分为两类：

• EXTERNAL：外部流转，Event执行变更状态
• INTERNAL：内部流转，Event执行不变更状态，现态与次态保持一致，是EXTERNAL流转的特例