• SCXML Parser
• 核心 API，用于 SCXML 文档的解析模块，该 SCXML 文档中的各个元素解析组装成对应的 Java 对象实现。
• DataModel
• 核心 API，用于实现 SCXML 状态机中的数据模型定义，将 SCXML 文档中的 datamodel 元素对应的子元素封装成 Java 对象，供状态机引挚在后续操作中使用。
• Context and Evaluators
• 核心 API，用于实现对 SCXML 状态机中上下文环境的保存和更改，以及对 SCXML 文档中表达式语言（例如 <log expr=”${data.value}” />）的解析操作。
• Executor
• 引挚执行器的实例化模块，核心 API，通过此模块完成一个完整引挚执行器的组装和实例化，并提供引挚启动，停止服务器基础功能模块。
• Triggering Event
• 核心 API，SCXML 引挚中事件的定义实现和执行模块。此模块完成一个外部事件的封装，事件池的组织以及具体的事件作用流程控制。
• Custom Actions
• 高级 API，SCXML 状态机引挚的自定义事件支持。除了 SCXML 标准自带的 <var >、<assign> 和 <log> 等标准事件外，程序人员可以进行自定义事件的开发工作，例如系统平台的构件添加、构件删除操作等，需要程序人员的扩展开发工作。以下代码为 Custom Actions 的使用范例。

          
               
       
        commons-scxml
                
       
        commons-scxml
                
       
        0.9
            
           
               
       
        commons-jexl
                
       
        commons-jexl
                
       
        1.1
            
           
               
       
        xalan
                
       
        xalan
                
       
        2.6.0
            
       
     

import org.apache.commons.scxml.SCXMLListener; import org.apache.commons.scxml.env.AbstractStateMachine; import org.apache.commons.scxml.model.ModelException; import org.apache.commons.scxml.model.State; import org.apache.commons.scxml.model.Transition; import org.apache.commons.scxml.model.TransitionTarget; import java.util.Timer; import java.util.TimerTask; public class StopWatch extends AbstractStateMachine {
   /**      * The events for the stop watch.      */     public static final String EVENT_START = "watch.start",             EVENT_STOP = "watch.stop", EVENT_SPLIT = "watch.split",             EVENT_UNSPLIT = "watch.unsplit", EVENT_RESET = "watch.reset";     /**      * The fragments of the elapsed time.      */     private int hr, min, sec, fract;     /**      * The fragments of the display time.      */     private int dhr, dmin, dsec, dfract;     /**      * The stopwatch "split" (display freeze).      */     private boolean split;     /**      * The Timer to keep time.      */     private Timer timer;     /**      * The display decorations.      */     private static final String DELIM = ":", DOT = ".", EMPTY = "", ZERO = "0";     public StopWatch() throws ModelException {
   super(StopWatch.class.getClassLoader().getResource("stopwatch.xml"));         getEngine().addListener(getEngine().getStateMachine(), new EntryListener());         System.out.println(StopWatch.class.getClassLoader().getResource("stopwatch.xml"));     } public void reset() {
   hr = min = sec = fract = dhr = dmin = dsec = dfract = 0;         split = false;     } public void running() {
   split = false;         if (timer == null) {
   timer = new Timer(true);             timer.scheduleAtFixedRate(new TimerTask() {
   @Override                 public void run() {
                       increment();                 }             }, 100, 100);         }     } public void paused() {
   split = true;     } public void stopped() {
   timer.cancel();         timer = null;     } public String getDisplay() {
           String padhr = dhr > 9 ? EMPTY : ZERO;         String padmin = dmin > 9 ? EMPTY : ZERO;         String padsec = dsec > 9 ? EMPTY : ZERO;         return new StringBuffer().append(padhr).append(dhr).append(DELIM).                 append(padmin).append(dmin).append(DELIM).append(padsec).                 append(dsec).append(DOT).append(dfract).toString();     } public String getCurrentState() {
   return ((State)getEngine().getCurrentStatus().getStates().iterator().next()).getId();     } private void increment() {
   if (fract < 9) {
   fract++;         } else {
   fract = 0;             if (sec < 59) {
   sec++;             } else {
   sec = 0;                 if (min < 59) {
   min++;                 } else {
   min = 0;                     if (hr < 99) {
   hr++;                     } else {
   hr = 0; //wrap                     }                 }             }         } if (!split) {
   dhr = hr;             dmin = min;             dsec = sec;             dfract = fract;         }     } /**      * A SCXMLListener that is only concerned about "onentry"      * notifications.      */     protected class EntryListener implements SCXMLListener {
   public void onEntry(final TransitionTarget entered) {
               System.out.println("Current State:"+entered.getId());         } public void onTransition(final TransitionTarget from,                                  final TransitionTarget to, final Transition transition) {
   // nothing to do         } public void onExit(final TransitionTarget exited) {
   // nothing to do         }     } }

public static void main(String[] args) throws ModelException {
       StopWatch stopWatch = new StopWatch();     Scanner input=new Scanner(System.in);     System.out.println("event: watch.start watch.stop watch.reset watch.split watch.unsplit");     while(true){
           String event=input.nextLine();         if(event.trim()!=null&&!event.trim().equals("")){
   if(event.equals("exit")) break;             else{
                   stopWatch.fireEvent(event);                 System.out.println(stopWatch.getCurrentState());                 System.out.print(stopWatch.getDisplay());             }         }     } }