Abstract
˜q™ç¯‡æ–‡ç« 主è¦æ˜¯ä»‹¾l了(ji¨£n)jBPM 4.0的基¼‹€æž¶æž„,以åŠ(qi¨¢ng)通过一个简å•çš„例åæ¥è®©å¤§å®¶çŸ¥é“怎么应用jBPM. ä¸ÞZ»€ä¹ˆé€‰æ‹©4.0版本å‘?以åŽçš„主‹¹ç‰ˆæœ¬åº”该是4.0版本çš?所以直接写4.0版本的了(ji¨£n).
<jbpm-configuration>
<import resource="jbpm.default.cfg.xml" />
<import resource="jbpm.tx.jta.cfg.xml" />
<import resource="jbpm.jpdl.cfg.xml" />
<import resource="jbpm.identity.cfg.xml" />
<import resource="jbpm.jobexecutor.cfg.xml" />
</jbpm-configuration>
<process-engine-context>
<repository-service />
<repository-cache />
<execution-service />
<history-service />
<management-service />
<identity-service />
<task-service />
<hibernate-configuration>
<cfg resource="jbpm.hibernate.cfg.xml" />
</hibernate-configuration>
...........
</process-engine-context>
<transaction-context>
<repository-session />
<db-session />
<message-session />
<timer-session />
<history-session />
<mail-session>
<mail-server>
<session-properties resource="jbpm.mail.properties" />
</mail-server>
</mail-session>
</transaction-context>
˜q™ä¸ªé…置文äšg主è¦åŒ…å«äº?process-engine-context'å’?'transaction-context'çš„é…¾|?
Object get(String key);
<T> T get(Class<T> type);
Object set(String key, Object value);
/**
* constructs the object.
* @param wireContext {@link WireContext} in which the object is created. This is also the {@link WireContext}
* where the object will search for other object that may be needed during the initialization phase.
* @return the constructed object.
*/
Object construct(WireContext wireContext);
/**
*called by the WireContext to initialize the specified object.
*/
void initialize(Object object, WireContext wireContext);
public interface Binding {
String getCategory();
/** does this binding apply to the given element? */
boolean matches(Element element);
/** translates the given element into a domain model java object.
* Use the parse to report problems.
*/
Object parse(Element element, Parse parse, Parser parser);
}
jbpm.cfg.xml �gt; jBPMConfigurationParser -> Binding �gt; Descriptor --> WireContext
或者更清楚çš?我们å¯ä»¥çœ‹ä¸‹ä¸‹é¢˜q™å¼ å›?sup>[
1].
我们ä¸å¦¨ä¹Ÿçœ‹ä¸‹ConfigurationTest‹¹‹è¯•.
public void testConfigurationServices() {
ProcessEngine processEngine = new Configuration()
.setXmlString(
"<jbpm-configuration>" +
" <process-engine-context>" +
" <repository-service />" +
" <execution-service />" +
" <management-service />" +
" </process-engine-context>" +
"</jbpm-configuration>"
)
.buildProcessEngine();
assertNotNull(processEngine);
assertNotNull(processEngine.getExecutionService());
assertNotNull(processEngine.getManagementService());
}
Configuration ¾cÀL˜¯jBPMçš„å…¥å?ä½ å¯ä»¥ä»Ž Configuration¾cÖM¸åˆ›å¾ProcessEngine,而从ProcessEngineä¸èŽ·å–到RepositoryService, ExecutionService, TaskService½{‰ç‰. Configuration¾c»é‡Œæœ‰ä¸¤ä¸ªå®žçŽ°ç±»,一个是JbpmConfiguration,˜q™æ˜¯é»˜è®¤çš„jBPM自带的Configuration解æžå™? å¦å¤–一个是SpringConfiguration,˜q™ä¸ªæ˜¯jBPMå’ŒSpring的集æˆ? 在这é‡?我们ž®±åªçœ‹ä¸‹JbpmConfiguration的实çŽ?在JbpmConfiguration¾c»é‡Œ,我们å¯ä»¥çœ‹åˆ°ä»–是˜q™ä¹ˆåŽ»è°ƒç”¨Parseræ? 解æžxmlçš?
protected void parse(StreamInput streamSource) {
isConfigured = true;
JbpmConfigurationParser.getInstance()
.createParse()
.pushObject(this)
.setStreamSource(streamSource)
.execute()
.checkErrors("jbpm configuration " + streamSource);
}
在这é‡?我们å¯ä»¥çœ‹åˆ°,jbpmçš„é…¾|®æ–‡ä»¶æ˜¯æœ‰ä¸¤ä¸ªå…ƒç´ 组æˆçš„,一个是process-engine-context,å¦å¤–一个是transaction-context. å…¶ä¸process-engine-context里é¢çš„å…ƒç´ æ˜¯åŒ…æ‹¬äº?ji¨£n)对外å‘布的æœåŠ? 比如repository-service, execution-service½{‰ç‰. 而transaction-context则包括了(ji¨£n)他的内部真æ£å®žçŽ°,比如repository-service对应repository-session. 也å¯ä»¥ç®€å•çš„把repository-servie看åšæ˜¯API, repository-session看åšæ˜¯SPI. ˜q™æ ·åšçš„好处æ˜?SPI的实çŽ?对API一点媄(ji¨£ng)å“都没有,很大½E‹åº¦ä¸Šæ供了(ji¨£n)一个容易集æˆçš„ç‰ÒŽ(gu¨©)€?
说到˜q™é‡Œ,应该对jBPMçš„IOC介ç»çš„å·®ä¸å¤šäº?我自己在用JBoss IDM project[2]æ¥å®žçŽ°jBPMçš„Identity moduleæ—?需è¦å¢žåŠ 如下的é…ç½®.
<jbpm-configuration>
<process-engine-context>
<jboss-idm-identity-session-factory jndi="java:/IdentitySessionFactory" />
</process-engine-context>
<transaction-context>
<jboss-idm-identity-session realm="realm://JBossIdentity" />
</transaction-context>
</jbpm-configuration>
于是,我需è¦å¢žåŠ 以下的¾cÀL¥å®Œæˆå¯¹è±¡çš„创建和实例åŒ? JbossIdmIdentitySessionFactoryBinding,JbossIdmIdentitySessionFactoryDescriptor,JbossIdmIdentitySessionBinding, JbossIdmIdentitySessionDescriptor 然åŽ,åœ?span class="emphasis">jbpm.wire.bindings.xml里é¢æ³¨å†Œæˆ‘ä»¬æ–°åŠ çš„Binding. 从上é¢æˆ‘们所说的,ä¸éš¾çœ‹å‡ºæœ¬èín˜q™ä¸ªIOC的实现机制也是很½Ž€å•çš„,而且也很å®ÒŽ(gu¨©)˜“扩展,如果说到时候和Spring, JBoss MC½{‰IOC容器的集æˆä¹Ÿæ˜¯å¾ˆæ–¹ä¾¿çš?
˜q™é‡Œ,我们看下jBPM-PVM概念和架æž?˜q™ä¹Ÿæ˜¯jBPM整个™å¹ç›®çš„æ ¸å¿?j¨©)所åœ?
Environment 的概å¿?主è¦æœ‰ä»¥ä¸‹çš„作用.
public abstract <T> T get(Class<T> type);
/** searches an object based on type. The search doesn take superclasses of the context elements
* into account.
* @return the first object of the given type or null in case no such element was found.
*/
public abstract <T> T get(Class<T> type, String[] searchOrder);
public interface RepositoryService {
NewDeployment createDeployment();
ProcessDefinitionQuery createProcessDefinitionQuery();
...
}
ExecutionService的一些方�
public interface ExecutionService {
ProcessInstance startProcessInstanceById(String processDefinitionId);
ProcessInstance signalExecutionById(String executionId);
...
}
public interface ManagementService {
void executeJob(long jobDbid);
JobQuery createJobQuery();
}
Command 概念的引å…?主è¦æ˜¯æƒ³å¯ÒŽ(gu¨©)‰€æœ‰çš„æ“作åšä¸€ä¸ªå°è£? å¯ä»¥è¯´ä¸Šé¢æ¯ä¸ªService的方法的实现都是通过实现一个Commandæ¥æ“ä½?然åŽé€šè¿‡CommandService调用到åŽé¢å…·ä½“的实现. 我们先æ¥çœ‹ä¸‹Command的接å?
public interface Command<T> extends Serializable {
T execute(Environment environment) throws Exception;
}
很简å?很典型的Command模å¼.
public interface CommandService {
/**
* @throws JbpmException if command throws an exception.
*/
<T> T execute(Command<T> command);
}
CommandService ˜q˜æœ‰ä¸€ä¸ªç‰¹æ€?ž®±æ˜¯å¯ä»¥é…ç½®Interceptor,比如事务ž®±æ˜¯åœ¨è¿™ä¸€Serviceä¸æ¥é…ç½®.看下CommandServiceçš„é…¾|?
<command-service>
<retry-interceptor />
<environment-interceptor />
<standard-transaction-interceptor />
</command-service>
Tip
å¯ä»¥è¯´CommandService是最适åˆå¤„ç†æ¨ªæˆªé?cross-cutting)çš„é—®é¢?比如事务,安全½{‰çš„. CommandService默认下是DefaultCommandService,如果是在使用ejb的情况下, 它的实现¾cÕd°±æ˜¯EjbLocalCommandServiceå’ŒEjbRemoteCommandService¾c? 所ä»?˜q™é‡Œæ˜¯è¿œ½E‹è°ƒç”?˜q˜æ˜¯æœ¬åœ°è°ƒç”¨,对用戯‚€(g¨¨)Œè¨€,都是é€æ˜Žçš?- retry-interceptor的主è¦ä½œç”¨å½“¼„°åˆ°StaleObjectException(也就是optimistic lockingå¤ÞpÓ|)æ—?˜q‡ä¸€å®šçš„æ—‰™—´åŽå†ž®è¯•.
- environment-interceptor的主è¦ä½œç”¨å°±æ˜?ä¿è¯command是在Environment范围内执è¡?也就是在执行command之å‰,openEnvironment,执行之åŽ,closeEnvironment.
- standard-transaction-interceptor的主è¦ä½œç”¨å°±æ˜¯å¤„ç†äº‹åŠ?
- authorization-interceptor,主è¦æ˜¯å¤„ç†æƒé™æ ¡éª?
我们先看下ActivityBehaviour的接å?
public interface ActivityBehaviour extends Serializable {
void execute(ActivityExecution execution) throws Exception;
}
public interface ExternalActivityBehaviour extends ActivityBehaviour {
//handles an external trigger.
void signal(ActivityExecution execution, String signalName, Map<String, ?> parameters) throws Exception;
}
public interface Transition extends ObservableElement {
/** the activity from which this transition leaves. */
Activity getSource();
/** the activity in which this transition arrives. */
Activity getDestination();
}
在pvmä¸?也包括了(ji¨£n)对event的支æŒ?event的接å£å¦‚ä¸?
public interface EventListener extends Serializable {
void notify(EventListenerExecution execution) throws Exception;
}
ClientProcessDefinition definition = ProcessDefinitionBuilder.startProcess("jeffProcess")
.startActivity("initial", new AutomaticActivity())
.initial()
.transition("first")
.endActivity()
.startActivity("first", new WaitStateActivity())
.transition("end", "endSignal")
.endActivity()
.startActivity("end", new AutomaticActivity())
.endActivity()
.endProcess();
我们最åŽä»Žæ•´ä½“上æ¥çœ‹ä¸‹˜q™äº›API之间的蔾p?我觉得Developer Guide上的˜q™ä¸ªå›„¡‰‡å¾ˆæ¸…楚的æè¿°äº?ji¨£n)他的架构æ€èµ\.
˜q™é‡Œéœ€è¦æ³¨æ„çš„æ˜?本èínPVM内部的浽E‹å®šä¹‰æ¨¡åž‹æ˜¯POJOçš?æ‰€ä»¥å¦‚æžœä½ åªæ˜¯æƒÏxµ‹è¯•æµ½E‹çš„æ£ç¡®æ€?ä½ åªéœ€è¦ç›´æŽ¥ä‹É用Clientçš„API,比如ClientProcessDefinition, ClientProcessInstance½{‰çš„API.
ä¸éœ€è¦åŽ»è°ƒç”¨RepositoryService, ProcessEngineService. ˜q™äº›Serviceæ˜¯é’ˆå¯¹ä½ æŠŠProcessDefinition在ä¿å˜åœ¨æ•°æ®åº“的情况下æ‰éœ€è¦ç”¨çš?
˜q™é‡Œ,我们ž®†åˆ©ç”¨PVM所æ供的Model,æ¥å®žçŽîC¸€ä¸ªåŸºæœ¬çš„工作‹¹å¼•æ“?
public interface ActivityBehaviour extends Serializable {
void execute(ActivityExecution execution) throws Exception;
}
public class Display implements ActivityBehaviour {
String message;
public Display(String message) {
this.message = message;
}
public void execute(ActivityExecution execution) {
System.out.println(message);
}
}
éšå¼(implicit)çš„executeæ–ÒŽ(gu¨©)³•æ‰§è¡Œ™åºåº
如果我们在execute()æ–ÒŽ(gu¨©)³•ä¸?没有昄¡¤ºçš„调用executionä¸çš„æ–ÒŽ(gu¨©)³•,比如waitForSignal(),take(transition)½{‰æ–¹æ³?那么默认的顺åºæ˜¯˜q™æ ·çš?我们先用˜q™ä¸ªDisplay,æ¥åˆ›å»ÞZ¸‹é¢çš„process.
ClientProcessDefinition processDefinition = ProcessDefinitionBuilder.startProcess("helloworld")
.startActivity("a", new Display("Hello"))
.initial()
.transition("b")
.endActivity()
.startActivity("b", new Display("World"))
.endActivity()
.endProcess();
processDefinition.startProcessInstance();
ž®×ƒ¼š(x¨¬)得到如下的结æž?
Hello
World
我们˜q™ä¸ªDisplay的节点就是采用的éšå¼execution执行æ–ÒŽ(gu¨©)³•.
public interface ExternalActivityBehaviour extends ActivityBehaviour {
//handles an external trigger.
void signal(ActivityExecution execution, String signalName, Map<String, ?> parameters) throws Exception;
}
我们接下æ¥å®žçŽîC¸€ä¸ªç®€å•çš„WaitState,实现ExternalActivityBehaviour的接å?
public class WaitState implements ExternalActivityBehaviour {
public void execute(ActivityExecution execution) {
execution.waitForSignal();
}
public void signal(ActivityExecution execution,
String signalName,
Map<String, Object> parameters) {
execution.take(signalName);
}
}
ClientProcessDefinition pd = ProcessDefinitionBuilder.startProcess("helloworld")
.startActivity("a", new WaitState())
.initial()
.transition("b", "b-transition")
.endActivity()
.startActivity("b", new WaitState())
.endActivity()
.endProcess();
ClientProcessInstance instance = pd.startProcessInstance();
instance.isActive("a")
instance.signal("b-transition");
instance.isActive("b")
接下æ?我们åŸÞZºŽå‰é¢ä¸¤ç§èŠ‚点的实çŽ?æ¥å®žçŽîC¸€ä¸ªç¨å¾®æ¯”较æ£å¼çš„‹¹ç¨‹(loan process).
ClientProcessDefinition pd = ProcessDefinitionBuilder.startProcess("loanprocess")
.startActivity("submit loan request", new Display("submit a loan request"))
.initial()
.transition("evaluate", "evaluate-transition")
.endActivity()
.startActivity("evaluate", new WaitState())
.transition("wiremoney", "approve")
.transition("end", "reject")
.endActivity()
.startActivity("wiremoney", new Display("wire the money"))
.transition("archive")
.endActivity()
.startActivity("archive", new WaitState())
.transition("end", "done")
.endActivity()
.startActivity("end", new WaitState())
.endActivity()
.endProcess();
instance = pd.startProcessInstance();
instance.signal("approve");
instance.signal("done");
˜q™æ ·çš„è¯,整个‹¹ç¨‹ž®×ƒ¼š(x¨¬)èµ°å‘äº?ji¨£n)end节点.
事äšg的订阅å¯ä»¥é€šè¿‡å®žçŽ°EventListeneræ¥å®žçŽ?
public interface EventListener extends Serializable {
void notify(EventListenerExecution execution) throws Exception;
}
具体的Event是由ObservableElementå’?span class="emphasis">EventNameæ¥æž„æˆçš„.
public interface EventListenerExecution extends OpenExecution {
void fire(String eventName, ObservableElement eventSource);
}
我们æ¥å®žçŽîC¸€ä¸ªç®€å•çš„EventListener, å«PrintLn
public class PrintLn implements EventListener {
String message;
public PrintLn(String message) {
this.message = message;
}
public void notify(EventListenerExecution execution) throws Exception {
System.out.println(message);
}
}
我们看下是怎么æ¥å®šä¹‰ä¸€ä¸ªå…·å¤‡æœ‰Eventsçš„ProcessDefinition:
ClientProcessDefinition pd = ProcessDefinitionBuilder.startProcess("ab")
.startActivity("a", new Display("Testing Event"))
.initial()
.transition("b")
.startEvent(Event.END)
.listener(new PrintLn("leaving a"))
.listener(new PrintLn("second message while leaving a"))
.endEvent()
.startEvent(Event.TAKE)
.listener(new PrintLn("taking transition"))
.endEvent()
.endActivity()
.startActivity("b", new WaitState())
.startEvent(Event.START)
.listener(new PrintLn("entering b"))
.endEvent()
.endActivity()
.endProcess();
我们å¯ä»¥çœ‹åˆ°,一个事件å¯ä»¥æœ‰æ— 穷多个的Listener(s).
è‡Ïx¤,我们主è¦çœ‹äº†(ji¨£n)PVM里é¢å†…部Model的一些设è®?ä¸€äº›æ ¸å¿?j¨©)的概念和API.
一ã€Â  Â?˜q行期环境就是一个é¤é¦?/strong>
1ã€Â  Â?æ供必è¦çš„æœåŠ?br /> 作äØ“(f¨´)一个é¤é¦†ï¼Œå¿…须有厨师åšé¥æˆ‘åƒï¼Œå¿…须有桌å和椅å。作ä¸ø™¿è¡ŒæœŸçŽ¯å¢ƒåŒæ ·å¦‚æ¤åQŒæˆ‘è¦å‘消æ¯åQŒä½ å¾—æ供我å‘消æ¯çš„ServiceåQŒæˆ‘è¦èŽ·å–节点ä“QåŠ¡ï¼Œä½ å¾—æ‰”ç»™æˆ‘TaskServiceã€?br />
2ã€Â  Â?æ供获喘q™äº›æœåŠ¡çš„统一方å¼
好å§åQŒæˆ‘ä¸ä¼š(x¨¬)亲自到厨房告诉厨师我惛_ƒä»€ä¹ˆï¼ˆå› äØ“(f¨´)我担å¿?j¨©)è¿™æ ·ä¸€æ¥æˆ‘ä¼?x¨¬)åƒä¸ä¸‹åŽ»ï¼?j¨ª)åQŒæˆ‘也ä¸ä¼?x¨¬)亲自到攉™“¶å°ç»™é’±ã€‚这些æœåŠ¡æœ‰ä¸€ä¸ªç»Ÿä¸€çš„获å–æ–¹å¼ï¼š(x¨¬)æœåŠ¡å‘˜ã€‚我æƒ? åƒä»€ä¹ˆå’Œ¾l“èÌŽåQŒå‘Šè¯‰æœåŠ¡å‘˜å›_¯ã€‚关键是˜q™ä¸€æ–¹å¼è¦ç»Ÿä¸€åQŒè¦‘›_¤Ÿ½Ž€å•ã€‚Spring最懒，把æœåŠ¡ç»™ä½ 全部注入了(ji¨£n)åQŒå½“ç„¶ä½ ä¹Ÿå¯ä»¥æ¡ä½BeanFactoryçš? ¾U¤çº¤¾l†æ‰‹åQŒä¸€ä¸ªä¸€ä¸ªçš„getã€?br />
3ã€Â  Â?æ供特定于我¾U¿ç¨‹ä¸å®‰å…¨çš„æœåŠ¡
我点äº?ji¨£n)一盘鱼香肉ä¸ï¼Œéš”å£ä¹Ÿç‚¹äº?ji¨£n)一盘鱼香肉ä¸ï¼Œ¾l“æžœæœåŠ¡å‘˜è®©æˆ‘们åƒåŒä¸€ç›˜é±¼é¦™è‚‰ä¸ã€‚我立刻跌™“væ¥ï¼š(x¨¬)é ï¼Œä½ ä»¬çš„æœåŠ¡ä¸æ˜¯çº¿½E‹å®‰å…¨çš„å—？åQHibernate çš„Sessionæ£æ˜¯å±žäºŽ˜q™ä¹ˆä¸€¿U情况，需è¦çŽ¯å¢ƒè¿›è¡Œéš”¼›»ï¼Œæˆ‘的唯一èŒè´£ž®±æ˜¯åƒé¥åQ我的领域逻辑是如何优¾ŸŽçš„˜q›é¤åQäØ“(f¨´)æ¤è¿˜è¦ä¸æ–é‡æž„我åƒé¥çš„姿势哩ã€?br /> 好ä¸å®ÒŽ(gu¨©)˜“åƒå®Œé¥ï¼Œä»˜å®Œ‹Æ¾ï¼Œæ£å‡†å¤‡ç¦»åœºã€‚æœåŠ¡å‘˜é£Žåº¦¾˜©ç¿©åœ°èµ°åˆ°æˆ‘çš„èínæ—，我以ä¸ø™¿˜æœ‰æ‰“折券供应åQŒç»“果是åQšæœåŠ¡å‘˜ž®å§è½Õd¯æœ±å”‡åQšå…ˆç”Ÿï¼ŒéºÈƒ¦(ch¨³)æ‚(zh¨¨n)¨æŠŠåƒå‰©çš„盘å清‹z—完毕ã€?br /> 崩溃åQ?br /> åƒæ•°æ®åº“˜qžæŽ¥çš„打开åQŒå…³é—ã€äº‹åŠ¡çš„打开ã€æ交ç‰éƒ½å±žäºŽè¿è¡ŒæœŸçŽ¯å¢ƒåº”该åšçš„事情ã€?br />
4ã€Â  Â?其他的七七八å…?br /> æ‚事ä¸å°‘åQŒä¾‹å¦‚统一的事件机制ã€æƒé™æ‹¦æˆªç‰½{‰ã€?br />
二ã€Â  Â?jBPM4çš„è¿è¡ŒæœŸçŽ¯å¢ƒ
好å§åQŒå…ˆæ¥çœ‹çœ‹å¦‚何å¾ç«‹jBPM4çš„è¿è¡ŒæœŸçŽ¯å¢ƒåQ?br />
Â
 Â
Â
  Environment environment = environmentFactory.openEnvironment();
  try {
Â
   Â
 everything available in this block Â
  } finally {
    environment.close();
  }
两个关键的类åQšEnvironmentFactoryå’ŒEnvironmentã€?br />
EnvironmentFactory是全局的，在整个应用程åºä¸ä¿æŒä¸€ä¸ªå®žä¾‹å³å¯ã€?br />
Environment则是æ¯æ¬¡æ–ÒŽ(gu¨©)³•è°ƒç”¨åˆ™è¦new一个ã€?br />
看看Environment的主è¦æ–¹æ³•ï¼š(x¨¬)
public abstract <T> T get(Class<T> type);
是的åQŒenvironment为我们的代ç æ供所需è¦çš„æœåŠ¡¾cÕd®žä¾‹ã€?br />
那么åQŒå¦‚何获得environmentåQ?br /> ¾l§ç®‹çœ‹ï¼š(x¨¬)
staticåQŒæˆ‘喜欢也。方ä¾Ñ€å¿«æøP¼Œä¸ç®¡æ˜¯åœ¨åœîC¸Šã€èžR上还是房™å¶ä¸ŠåQŒéšå¤„都å¯è°ƒç”¨ã€?br />
那么åQŒäØ“(f¨´)什么Environmentæ¯æ¬¡è°ƒç”¨è¦new呢？
好å§åQŒå½“ä½ éœ€è¦èŽ·å–æ•°æ®åº“Session的时候，是ä¸æ˜¯æ¯‹Æ¡éƒ½è¦new呢。Environmentæ供的æœåŠ¡é‡ŒåŒ…括äº?ji¨£n)éž¾U¿ç¨‹å®‰å…¨çš„æ•°æ®åº“æ“作æœåŠ¡ã€?br />
三ã€Â  Â?jBPM4˜q行期环境的实现
1ã€JbpmConfiguration
JbpmConfiguration是jBPM4里最é‡è¦çš„ç±»åQŒå®ƒæ˜¯æ•´ä¸ªåº”用程åºçš„å…¥å£ã€‚它实现äº?ji¨£n)EnvironmentFactory接å£ã€?br />
     JbpmConfigurationåŠ è²jBPMæ€Èš„é…置文äšgåQŒè¿˜æ˜¯å¤§æ¦‚扫一下这个酾|®æ–‡ä»Óž¼š(x¨¬)
  <process-engine-context>
Â
    <repository-service />
    <repository-cache />
    <execution-service />
    <history-service />
    <management-service />
    <identity-service />
    <task-service />
    <hibernate-configuration>
      <cfg resource="jbpm.hibernate.cfg.xml" />   Â
    </hibernate-configuration>
    <hibernate-session-factory />
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  </process-engine-context>
  <transaction-context>
    <repository-session />
    <pvm-db-session />
    <job-db-session />
    <task-db-session />
    <message-session />
    <timer-session />
    <history-session />
  </transaction-context>
</jbpm-configuration>
é…置文äšg被分ä¸ÞZº†(ji¨£n)两部分，分别是：(x¨¬)process-engine-contextå’Œtransaction-contextã€?br /> 对应于两个IOC容器åQˆWireContextåQ‰çš„é…置文äšgã€?br />
作äØ“(f¨´)EnvironmentFactoryåQŒJbpmConfigurationæŒæœ‰æˆå“process-engine-context对应的IOC容器 åQˆå…¨å±€çš„）(j¨ª)实例åQŒæŒæœ‰åŠæˆå“transaction-contextçš„WireDefinition。当调用openEnvironmentæ–ÒŽ(gu¨©)³• æ—Óž¼ŒJbpmConfigurationä¼?x¨¬)new EnvironmentåQŒç„¶åŽå°†process-engine-context IOCå¡«å……å…¥environmentåQŒåŒæ—¶åˆå§‹åŒ–transaction-context IOCåQŒåƈž®†å…¶ä¹Ÿå¡«å……å…¥environmentã€‚è¿™æ ·é€šè¿‡environmentž®±å¯ä»¥èŽ·å¾—所有所需è¦çš„æœåŠ¡åQŒåŒ…括全局的和éžçº¿½E‹å®‰å…¨çš„æœåŠ¡å®žä¾‹ã€‚也ž®±æ˜¯ environmenté€è¿‡IOC容器æä¾›äº?ji¨£n)查扑ք¿UæœåŠ¡çš„能力ã€?br />
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2ã€ä¸Ž¾U¿ç¨‹¾l‘定的environment
environmentåˆå§‹åŒ–之å?é¿å…å‚æ•°ä¼ é€’å¾—ä¸€å¡Œç³Šæ¶‚çš„æ–¹å¼ž®±æ˜¯ž®†environment与线½E‹ç»‘定。看Environment的代ç ：(x¨¬)
  static ThreadLocal<Stack<Environment>> currentEnvironmentStack = new ThreadLocal<Stack<Environment>>();
是的åQŒåœ¨openEnvironmentæ—Óž¼Œæœ‰è¿™ä¹ˆä¸€è¡Œä»£ç ：(x¨¬)
˜q™æ ·environmentž®×ƒ¸Ž¾U¿ç¨‹¾l‘定äº?ji¨£n)，å¯ä»¥é€šè¿‡Environment.getCurrent()ä»ÀL„调用äº?ji¨£n)ã€?br />
哪里有压˜q«ï¼Œå“ªé‡Œž®±æœ‰æ”¾æŠ—ã€?br /> 在environment.close()æ–ÒŽ(gu¨©)³•é‡Œï¼š(x¨¬)
OKåQŒç»“æŸã€?br />
一ã€Â  Â?Jbpm4 IOC容器介ç»
IOC容器的目的是½Ž¡ç†¾l„äšg和实现组件之间的解耦。和Spring里的BeanFactory对应åQŒJbpm4里的接å£æ˜¯ContextåQŒå…·ä½“实现则æ˜? WireContext。Context实际在Jbpm4里有更多的å«ä¹‰ï¼Œå®ƒä¸ŽEnvironment一èµøP¼Œå…±åŒæž„æˆäº?ji¨£n)代ç è¿è¡Œçš„˜q行期环境。在˜q™ä¸ªçŽ¯å¢ƒ 里å¯ä»¥èŽ·å–ç³»¾lŸçš„¾l„äšgåQŒæ›´ä¸ºé‡è¦çš„是æ供了(ji¨£n)æ•°æ®åº“连接（sessionåQ‰å’Œäº‹åŠ¡åQˆè¿™ä¸ªç¨åŽä¼š(x¨¬)è®ÔŒ¼‰(j¨ª)ã€?br />
å…ˆæ¥çœ‹çœ‹Context接å£çš„æ ¸å¿?j¨©)方法ï¼?x¨¬)
  <T> T get(Class<T> type);
很明显，æ供两ç§ä»Žå®¹å™¨é‡ŒèŽ·å–¾l„äšg的方法，一¿U是通过nameåQŒä¸€¿U是通过typeã€?br />
对于IOC容器æ¥è¯´åQŒä¸€èˆ¬æƒ…况下都会(x¨¬)æ供一¿UåŠ è½½çš„æ–¹å¼åQŒæ¯”如从xmlæ–‡äšg˜q›è¡ŒåŠ è²ã€ä»Žèµ„æºæ–‡äšg˜q›è¡ŒåŠ è²ã€‚Jbpm4é€è¿‡WireParser具备从xmlåŠ è²çš„能力ã€?br />
æ¤å¤–åQŒW(xu¨¦)ireContext通过一个Map¾~“å˜åˆå§‹åŒ–åŽçš„组件ã€?br />
二ã€Â  Â?Jbpm4 IOC容器实现
容器的实现有五个关键¾cÕd’ŒæŽ¥å£åQŒåˆ†åˆ«æ˜¯åQšWireParserã€Bindingã€Descriptorã€WireDefinitionå’ŒW(xu¨¦)ireContextã€?br /> Â
WireParserè¯Õd–xmlæ–‡äšgåQŒåŒæ—¶WireParserä¼?x¨¬)åŠ è½½ä¸€¾pÕdˆ—çš„Binding(默认从jbpm.wire.bindins.xmlæ–‡äšgè¯Õd–åŠ è²)ã€?br />
Bindingè´Ÿè´£æ ÒŽ(gu¨©)®xmlé‡Œå…ƒç´ çš„tagž®†xmlå…ƒç´ è½¬æ¢ä¸ºå¯¹åº”çš„Descriptorã€?br />
Descriptorè´Ÿè´£åˆå§‹åŒ–对象。它们被æ·ÕdŠ 到WireDefinitionã€?br />
WireDefinition被WireParser˜q”回¾l™WireContext。WireContext创å¾å¯¹è±¡æ—¶ä¼š(x¨¬)讉K—®WireDefinition里的DescriptoråQŒåŒæ—¶å°†åˆå§‹åŒ–对象的ä»ÕdŠ¡å§”托¾l™Descriptor自èínã€?br />
需è¦æ³¨æ„的是：(x¨¬)Jbpm4在åˆå§‹åŒ–对象时有ç€å››ç§½{–ç•¥åQŒåˆ†åˆ«æ˜¯åQšåšg˜qŸåˆ›å»ºå’Œåˆå§‹åŒ–ã€åšg˜qŸåˆ›å»ºå’Œç«‹åˆ»åˆå§‹åŒ–ã€ç«‹åˆÕdˆ›å»ºå’Œå»¶è¿Ÿåˆå§‹åŒ–ã€ç«‹åˆÕdˆ›å»ºå’Œç«‹åˆ»åˆå§‹åŒ–ã€?br />
立刻创å¾åQšåœ¨WireContext创å¾å®Œæ¯•åŽå¯¹è±¡å°±å·²ç»åˆ›å¾ã€?br /> 延迟创å¾åQšè°ƒç”¨WireContextçš„getæ–ÒŽ(gu¨©)³•èŽ·å–该对象时æ‰åˆ›å»ø™¯¥å¯¹è±¡ã€?br /> åˆå§‹åŒ–：(x¨¬)一般完æˆå¯¹è±¡å±žæ€§çš„注入½{‰æ“作ã€?br />
三ã€Â  Â?Jbpm4 IOC容器在Jbpm4里的应用
IOC容器在Jbpm4里最é‡è¦çš„ä½œç”¨å°±æ˜¯åŠ è½½Jbpmçš„æ€Èš„é…置文äšgåQˆé»˜è®¤æ˜¯jbpm.cfg.xmlåQ‰ï¼Œ˜q™ä¹Ÿæ˜¯æ•´ä¸ªJbpm应用的è“vç‚V€‚大概扫一下这个酾|®æ–‡ä»Óž¼š(x¨¬)
<jbpm-configuration xmlns="http://jbpm.org/xsd/cfg">
  <process-engine-context>
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    <repository-service />
    <repository-cache />
    <execution-service />
    <history-service />
    <management-service />
    <identity-service />
    <task-service />
    <hibernate-configuration>
      <cfg resource="jbpm.hibernate.cfg.xml" />   Â
    </hibernate-configuration>
    <hibernate-session-factory />
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  </process-engine-context>
  <transaction-context>
    <repository-session />
    <pvm-db-session />
    <job-db-session />
    <task-db-session />
    <message-session />
    <timer-session />
    <history-session />
  </transaction-context>
</jbpm-configuration>
å¯ä»¥çœ‹åˆ°é…置文äšg被分ä¸ÞZº†(ji¨£n)两部分，分别是：(x¨¬)process-engine-contextå’Œtransaction-context。在实际应用ä¸ï¼Œå®ƒä»¬ 分别对应ç€ä¸¤ä¸ªä¸åŒçš„WireContext:ProcessEngineContextå’ŒTransactionConextã€? ProcessEngineContext覆盖äº?ji¨£n)jbpm4里最é‡è¦çš„æœåŠ¡ç±»åQŒè¿™äº›ç±»æ˜¯å…¨å±€å”¯ä¸€çš„，当然åQŒProcessEngineContext也是 独æ¤ä¸€ä»½ã€‚本是åŒæ ¹ç”ŸåQŒå‘½˜qå„ä¸åŒã€‚TransactionConext则是在毋ơopenEnvironmentæ—‰™‡æ–°åˆ›å»ºï¼Œå› äØ“(f¨´)其包å«äº†(ji¨£n)æ•°æ®åº“连接和 事务ã€?br />
贯穿于整个Jbpm4ä¸ï¼Œ˜q™ä¸¤ä¸ªContext被压到Environment里（Environment和线½E‹ç»‘定）(j¨ª)åQŒåœ¨ä»ÖM½•éœ€è¦çš„地方都能æ供一æ¡é¾™çš„æœåŠ¡ã€‚于是，在很多领域类里，利用˜q™äº›æœåŠ¡å®žçŽ°å……血模型ž®±æ˜¯å¾ˆé¡ºç†æˆç« 的一件事äº?ji¨£n)ã€?br />
æ€È»“: ProcessEngineContext¾l™å¼•æ“Žé¢†åŸŸæ¨¡åž‹æ供全局的组件查找；TransactionConextæ供数æ®åº“相å…ÏxœåŠ¡ã€?br />
jBPM3 vs jBPM4
JBoss Goup ç›®å‰å·²ç»å‘布äº?/span> jBPM4 Alpha1 版本åQŒåœ¨ç‰ˆæœ¬ 4 ä¸æœ€å¤§çš„å˜åŒ–ž®±æ˜¯å¼•å…¥ PVM åQˆæµ½E‹è™šæ‹ŸæœºåQ‰çš„概念åQŒè€Œå¼•æ“Žå†…部的调度½Ž—法ä¸é‡è¦çš„ Token 机制åQŒåœ¨æ–°ç‰ˆä¸ä¹ŸåŽÀLŽ‰äº?ji¨£n)，¾Uµè§‚整个代ç åQŒå˜åŒ–å¯ä»¥è¯´éžå¸¸çš„大åQŒç¬”者接下楞®Þp¯•ç€æ¥æ¯”较一下这¿Uå˜åŒ–，让大家能有个直观的认识。当ç„?/span> Jbpm4 åœ?/span> JBoss 的官方网站上çš?/span> Road map ä¸ï¼Œåœ¨ä»Šòq´çš„ 7 æœ?/span> 1 åäh‰ä¼?x¨¬)å‘布第一个æ£å¼ç‰ˆæœ¬ï¼Œå› æ¤åŽç®‹å¯èƒ½˜q˜ä¼š(x¨¬)有å˜åŒ–ã€?/span>
1ã€?/span>  ‹¹ç¨‹å®šä¹‰å¯¹è±¡çš„å˜åŒ–：(x¨¬)
Jbpm3 ‹¹ç¨‹å®šä¹‰å¯¹è±¡å…³ç³»å›¾ï¼š(x¨¬)
图一 jbpm3‹¹ç¨‹å®šä¹‰å¯¹è±¡å…³ç³»å›?/span>
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从上图我们å¯ä»¥çœ‹å‡?gu¨®)™¿?/span> jbpm3 ä¸ï¼Œ GraphElement 是浽E‹å›¾ä¸æ‰€æœ‰æµ½E‹å…ƒç´ 的父对象，而整个浽E‹æ˜¯ç”?/span> ProcessDefinition ã€?/span> Node ã€?/span> Transition 三个主è¦å¯¹è±¡æž„æˆåQ?/span>
 
 图二 PVM实体对象关系å›?/span>     Â
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从上囑֯以看出，ç”׃ºŽ PVM 概念的引入，所以在 jbpm3 ä¸çš„ Graph 包在 jbpm4 ä¸è¢«¿U»é™¤äº?ji¨£n)。在 pvm ä¸ï¼Œåœ¨è®¾è®¡æœŸåQŒæ‰€æœ‰èŠ‚ç‚¹å…ƒç´ çš„çˆ¶ç±»ä¸?/span> ProcessElementImpl åQŒæµ½E‹çš„主覾l„æˆå…ƒç´ Nodelmpl ã€?/span> TransitionImpl ã€?/span> ProcessDefinitionImpl ã€?/span> EventImpl 则都直接或间接ç‘ô承自 ProcessElementImpl 。在˜q行期：(x¨¬) jbpm4 把浽E‹çš„˜q行期行为定义äØ“(f¨´)执行行äØ“(f¨´)åQ?/span> ExecutionImpl åQ‰åŠ(qi¨¢ng)原åæ“作行äØ“(f¨´)åQ?/span> AtomicOperation åQŒå…¶å…·ä½“实现ä¸?/span> ExecuteNode ã€?/span> ProceedToDestination ã€?/span> TakeTranstion ã€?/span> MoveToParentNode ã€?/span> MoveToChildNode ã€?/span> signal åQ‰ï¼Œå…¶ä¸ ExecutionImpl 是浽E‹å®žä¾‹ã€æ´»åŠ¨å®žä¾‹ã€äº‹ä»¶ç›‘å¬å™¨çš„所有执行期行äØ“(f¨´)的实现类ã€?/span>
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图三 jpdl ˜q行期活动实体对象关¾pÕd›¾
 上图æ˜?/span> jbpm4 在è¿è¡ŒæœŸçš„活动实例对象关¾pÕd›¾åQŒä»Žå›¾ä¸æˆ‘们å¯ä»¥çœ‹å‡ºåQŒåœ¨˜q行期， jbpm4 ä¸å®šä¹‰äº†(ji¨£n)两个‹zÕdŠ¨æŽ¥å£ Activity å’?/span> ExternalActivity åQŒå…¶ä¸?/span> ExternalActivity ¾l§æ‰¿è‡?/span> Activity ã€?/span> Activity 是所有自动活动节点的父接å£ï¼Œå…¶å®žçŽ°ç±»ä¸?/span> JpdlActivity åQŒè€?/span> JpdlActivity åˆè¡ç”Ÿå‡ºäº?ji¨£n)ã€?/span> StartActivity ã€?/span> JoinActivity ã€?/span> ForkActivity ã€?/span> EndActivity ã€?/span> CreateTimerActivity ã€?/span> JavaActivity ã€?/span> EsbActivity ½{‰å®žä¾‹æ´»åŠ¨å¯¹è±¡ã€‚è€?/span> ExternalActivity 是具有ç‰å¾…状æ€çš„‹zÕdŠ¨åQ?/span> StateActivity åQ‰çˆ¶æŽ¥å£åQŒåƒäººå·¥‹zÕdŠ¨ TaskActivity ž®±æ˜¯å®žçŽ°äº?ji¨£n)æ¤æŽ¥å£ã€?/span>
 2ã€?/span> Â æ ¸å¿ƒ(j¨©)引擎的调度算æ³?/span>
Jbpm3 çš„æ ¸å¿?j¨©)调度算法是åŸÞZºŽ Token 机制的，在è¿è¡ŒæœŸ˜q™ä¸ª Token åœ?/span> Node Instance 之间‹¹è{åQŒä¾é?/span> Token 的触å‘æ¥æŽ¨è¿›‹¹ç¨‹ã€‚具体的调度机制åQŒå¯å‚åŠ èƒ¡é•¿åŸŽçš„æ–‡ç« åQ?/span> http://blog.csdn.net/james999/archive/2007/09/02/1769592.aspx åQ‰ï¼›å…¶å®ž˜q™ä¸ª Token æ¥è‡ªäº?/span> Pertri-net åQŒæ„Ÿå…´è¶£çš„读者å¯ä»¥åŽ»çœ?/span> Pertri-net ä¸çš„ Token å?/span> Place ã€?/span>
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Jbpm4 则去掉了(ji¨£n) Token åQŒé‚£ä¹ˆå®ƒçš„æ ¸å¿?j¨©)è°ƒåº¦æœºåˆ¶æ˜¯æ€Žæ ·å®žçŽ°çš„å‘¢åQ?/span>
 图五 jbpm4‹¹ç¨‹å¯åŠ¨åºåˆ—å›?/span>
囑օ jbpm4 ‹¹ç¨‹æŽ¨è¿›åºåˆ—å›?/span>
图五是在 jbpm4 ä¸å¯åŠ¨ä¸€ä¸ªæµ½E‹å®žä¾‹çš„执行åºåˆ—图，囑օ是节ç‚ÒŽ(gu¨©)Ž¨˜q›çš„执行åºåˆ—图，从上é¢ä¸¤ä¸ªå›¾ä¸æˆ‘们å¯ä»¥çœ‹åˆ°æ ¸å¿?j¨©)的调度是ä¾æ?/span> Execution çš„è{¿UÀL¥å®žçŽ°çš„（ ExecutionImpl å¯ä»¥æ˜?/span> ActivityExecution ã€?/span> ClientProcessInstance ã€?/span> EventListenerExecution 的实例）(j¨ª)åQ?/span> Execution 实际上就是å–代了(ji¨£n) Jbpm3 ä¸çš„ Token åQ?/span> Execution çš„è{¿UÕd®žé™…上ž®±æ˜¯æ ÒŽ(gu¨©)®çŠ¶æ€æœºçš„嘘q（ ActivityExecution ã€?/span> ClientProcessInstance ã€?/span> EventListenerExecution 实例之间的切æ¢ï¼‰(j¨ª)åŠ ä¸Šè°ƒç”¨ç›¸åº”çš„åŽŸåæ“作：(x¨¬) ExecuteNode ã€?/span> MoveToChildNode ã€?/span> MoveToParentNode ã€?/span> ProceedToDesitination ã€?/span> Signal ã€?/span> TakeTransition åQˆè¯¦è§?/span> pvm/internal/model/op 包下的相关类åQ‰æ¥å®žçŽ°çš„。所ä»?/span> Execution 实例的集åˆåŠ(qi¨¢ng)有å‘囑֮žé™…上ž®±æ˜¯˜q行期的路径ã€?/span>
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3ã€?/span>  Event-Action 机制的å˜åŒ?/span>
åœ?/span> jbpm3 ä¸æ˜¯åŸÞZºŽ Event-Action 机制æ¥å®žçŽîCº‹ä»¶ä¸ŽåŠ¨ä½œçš„触å‘çš„åQŒä½†æ˜¯åœ¨ jbpm4 ä¸åˆ™é‡‡ç”¨è§‚察者模å¼æ¥è§¦å‘事äšg的。所有用戯‚‡ªå·±å®šä¹‰çš„动作åQŒå…¨éƒ¨è¦å®žçŽ° EventListener 接å£åQŒè¿™äº›åŠ¨ä½œä½œä¸ºç›‘å¬è€…（ž®±æ˜¯äº‹äšg Event 的观察è€?/span> Observer åQ‰æ³¨å†Œåˆ°ç›¸åº”çš„æµ½E‹å®šä¹‰å¯¹è±¡ä¸ŠåQ?/span> ProcessElement 或è€?/span> Node åQ‰ï¼Œè€Œäº‹ä»?/span> Event 则作ä¸ø™¢«è§‚察的对象（实际上就æ˜?/span> Observerable åQ‰ï¼Œå®žé™…上在 jbpm4 ä¸ä¸“门定义出äº?ji¨£n)一个对è±?/span> ObservableElementImpl åQŒæµ½E‹å®šä¹‰ä¸çš?/span> NodeImpl ã€?/span> TransitionImpl ã€?/span> ProcessDefinitionImpl å‡ç‘ô承自æ¤å¯¹è±¡ï¼Œå› 椘q™äº›å…ƒç´ 本èínž®±å¯ä»¥ä½œä¸?/span> Observerable 而被观察者æ¥ç›‘控ã€?/span>
4ã€?/span>  客户端接å£çš„å˜åŒ–
åœ?/span> jbpm4 ä¸å¯¹å®¢æˆ·ç«¯çš„接壾lŸä¸€ä¸?/span> 7 个æœåŠ¡æŽ¥å£ï¼š(x¨¬) ProcessService ã€?/span> ExecutionService ã€?/span> CommandService ã€?/span> TaskService ã€?/span> ManagementService ã€?/span> HistoryService ã€?/span> IdentityService åQŒè¿™ 7 个接å£å¯ä»¥ä»Ž ProcessEngine 接å£ä¸èŽ·å¾—， jbpm4 在å¯åŠ¨çš„˜q‡ç¨‹ä¸ç”± JbpmConfiguration 负责构å¾å¼•æ“Žã€?/span>
Ø ProcessService- ‹¹ç¨‹å®šä¹‰çš„æœåŠ¡æŽ¥å£ï¼ŒåŒ…括å¯ÒŽ(gu¨©)µ½E‹å®šä¹‰çš„部çÖvã€æŸ¥è¯¢ã€åˆ 除æ“作；
Ø ExecutionService- 执行æœåŠ¡æŽ¥å£åQŒåŒ…括å¯åŠ¨æµ½E‹ã€å®žä¾‹æŽ¨˜q›ã€è®¾¾|®å˜é‡ç‰æ“作åQ?/span>
Ø CommandService-Command 模å¼çš„æœåŠ¡æŽ¥å£ï¼Œå®žé™…上就是将客户端的è¯äh±‚全部ž®è£…在一个调用接å£ä¸åQŒç„¶åŽç”±˜q™ä¸ªæŽ¥å£åŽ»è°ƒç”?/span> Command 接å£çš„众多实玎ͼˆ StartExecutionCmd ã€?/span> SignalCmd ã€?/span> SetVariablesCmd ã€?/span> GetTimersCmd ã€?/span> DeployCmd ã€?/span> NewTaskCmd ã€?/span> SubmitTask ã€?/span> ExecuteJobCmd ½{‰ç‰åQŒå…·ä½“å¯å‚åŠ pvm/internal/cmd åQ?/span> task/internal/cmd 包åŠ(qi¨¢ng)其它包下实现 Command 接å£çš„ç±»åQ‰ï¼Œ˜q™æ˜¯å…¸åž‹çš?/span> Command 模å¼çš„应用，感兴‘£çš„读者å¯ä»¥åŽ»äº?ji¨£n)解设计模å¼ä¸çš?/span> Command 模å¼åQ?/span>
Ø TaskService- 人工‹zÕdŠ¨çš„æœåŠ¡æŽ¥å£ï¼ŒåŒ…括对ä“Q务的创å¾ã€æ交ã€æŸ¥è¯¢ã€ä¿å˜ã€åˆ 除ç‰æ“作åQ?/span>
Ø ManagementService-web ½Ž¡ç†æŽ§åˆ¶å°çš„æœåŠ¡æŽ¥å£åQŒç›®å‰åªæœ‰èŽ·å¾—消æ¯åŠ(qi¨¢ng)计时器的接å£å®žçŽ°åQ?/span>
Ø HistoryService- ç›®å‰æœ‰å¯¹åŽ†å²åº“ä¸çš„æµ½E‹å®žä¾‹ã€æ´»åŠ¨å®žä¾‹è¿›è¡ŒæŸ¥è¯¢ã€æŸä¸ªæµ½E‹å®šä¹‰ä¸çš„所有活动的òq›_‡æŒç®‹æ—‰™—´ã€æŸä¸ªæµ½E‹å®šä¹‰ä¸çš„æŸä¸ªæ´»åŠ¨å®žä¾‹çš„转移的执行次æ•?/span>
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