Liferay7 BPM门户开发之2: BPMN 2.0 规范入门 （Activiti BPMN extensions）

Liferay最大的问题是BPM弱,如果做企业开发,BPM必不可少,所以直入主题,做个BPMN2入门.

本文参考地址：http://activiti.org/userguide/index.html#bpmnConstructs

BPMN 2.0中的重要概念：

• Events 事件 
• Sequence Flow 顺序流
• Gateways 网关
• Tasks 任务
• Sub-Processes and Call Activities 子流程
• Transactions and Concurrency 事务并发
• Process Initiation Authorization 初始化认证
• Data objects 流程数据

其他相关项：

• Form properties 表单属性
• External form rendering 外部表单集成

1、Events

1、1 Timer Event Definitions

由时间触发的时间，用于

• start event
• intermediate event
• boundary event

必须有确切的一个元素，分别是：

timeDate

<timerEventDefinition> <timeDate>2011-03-11T12:13:14</timeDate> </timerEventDefinition>

在确切的时间点执行

timeDuration

<timerEventDefinition> <timeDuration>P10D</timeDuration> </timerEventDefinition>

 从最后一个任务完成后10天开始执行

timeCycle

<timerEventDefinition>
　　<timeCycle activiti:endDate="2015-02-25T16:42:11+00:00">R3/PT10H</timeCycle>
</timerEventDefinition>
或者变量形式：
<timerEventDefinition>
　　<timeCycle>R3/PT10H/${EndDate}</timeCycle>
</timerEventDefinition>

循环3次，间隔10小时

也可以使用cron expressions ：http://www.quartz-scheduler.org/documentation/

1.2 Signal Event Definitions

一个例子：https://github.com/chanjarster/activiti-learn/wiki/%E8%AF%A6%E8%A7%A3signal%20event

1.3 Message Event Definitions

想象一下，作为一个嵌入式的流程引擎（不是国内很多固化Hardcode式的流程引擎），Activiti关心的是实际从第三方应用系统接收的消息。这将是环境依赖和需要特定平台的活动。
比如：

• 连接到JMS（java消息服务）队列
• 处理一个WebService
• REST请求
• MQ队列的消息处理
• XMPP消息监听
• ......

总之，消息是和应用程序相关联的。

在您收到您的应用程序中的一个消息后，您必须决定该如何处理它。如果消息应该触发一个新的流程实例的开始，process instance的启动不应该使用runtimeService.startProcessInstanceByKey，在以下方法中选择：

• ProcessInstance startProcessInstanceByMessage(String messageName);
• ProcessInstance startProcessInstanceByMessage(String messageName, Map<String, Object> processVariables);
• ProcessInstance startProcessInstanceByMessage(String messageName, String businessKey, Map<String, Object> processVariables);

<definitions id="definitions"
  xmlns="http://www.omg.org/spec/BPMN/20100524/MODEL"
  xmlns:activiti="http://activiti.org/bpmn"
  targetNamespace="Examples"
  xmlns:tns="Examples">

  <message id="newInvoice" name="newInvoiceMessage" />
  <message id="payment" name="paymentMessage" />

  <process id="invoiceProcess">

    <startEvent id="messageStart" >
        <messageEventDefinition messageRef="newInvoice" />
    </startEvent>
    ...
    <intermediateCatchEvent id="paymentEvt" >
        <messageEventDefinition messageRef="payment" />
    </intermediateCatchEvent>
    ...
  </process>

</definitions>

有不同的方式来启动事件，Message Event Definitions 就非常有用了

例如订单可能来自call center ，也可以来自web shop

1.4 Start Events

开始事件总是捕捉型（Catching）的，比如一个消息接收，比如一个时间触发，总是有指定的触发。

<startEvent id="request" activiti:initiator="initiator" />

启动：

try {
  identityService.setAuthenticatedUserId("bono");
  runtimeService.startProcessInstanceByKey("request");
} finally {
  identityService.setAuthenticatedUserId(null);
}

1.5 None Start Event

一个无启动事件在技术上意味着启动过程实例的触发器是未指定的。而且没有子元素节点。

一个有启动表单的例子：

<startEvent id="request" activiti:formKey="org/activiti/examples/taskforms/request.form" />

图形是一个空心圆：

1.6 Timer Start Event

时间启动事件，是一个时钟在中间的圆：

1.7 Boundary Events

边界事件是catching型的，连接到一个活动（一个边界事件永远不会throwing）的事件。
这意味着，当活动正在运行时，事件正在侦听某种类型的触发器。当事件被捕获时，该活动被中断，顺序流下行。

<boundaryEvent id="escalationTimer" cancelActivity="true" attachedToRef="firstLineSupport">
  <timerEventDefinition>
    <timeDuration>PT4H</timeDuration>
  </timerEventDefinition>
</boundaryEvent>

<boundaryEvent id="boundary" attachedToRef="task" cancelActivity="true">
          <messageEventDefinition messageRef="newCustomerMessage"/>
</boundaryEvent>

2. Sequence Flow

2.1 Conditional sequence flow

带有UEL条件表达式的顺序流

<sequenceFlow id="flow" sourceRef="theStart" targetRef="theTask">
  <conditionExpression xsi:type="tFormalExpression">
    <![CDATA[${order.price > 100 && order.price < 250}]]>
  </conditionExpression>
</sequenceFlow>

2.2 Default sequence flow

任务和网关都可以有默认顺序流。

<exclusiveGateway id="exclusiveGw" name="Exclusive Gateway" default="flow2" />
<sequenceFlow id="flow1" sourceRef="exclusiveGw" targetRef="task1">
  <conditionExpression xsi:type="tFormalExpression">${conditionA}</conditionExpression>
</sequenceFlow>
<sequenceFlow id="flow2" sourceRef="exclusiveGw" targetRef="task2"/>
<sequenceFlow id="flow3" sourceRef="exclusiveGw" targetRef="task3">
  <conditionExpression xsi:type="tFormalExpression">${conditionB}</conditionExpression>
</sequenceFlow>

flow2就是默认顺序流，当所有条件不满足，则选择默认顺序流。

3 Gateways

 3.1 Exclusive Gateway

异或网关

     输入：只要有一个活动节点到达该网关那么就触发

     输出：有多个输出点时，只会触发一个

<exclusiveGateway id="exclusiveGw" name="Exclusive Gateway" />

<sequenceFlow id="flow2" sourceRef="exclusiveGw" targetRef="theTask1">
  <conditionExpression xsi:type="tFormalExpression">${input == 1}</conditionExpression>
</sequenceFlow>

<sequenceFlow id="flow3" sourceRef="exclusiveGw" targetRef="theTask2">
  <conditionExpression xsi:type="tFormalExpression">${input == 2}</conditionExpression>
</sequenceFlow>

<sequenceFlow id="flow4" sourceRef="exclusiveGw" targetRef="theTask3">
  <conditionExpression xsi:type="tFormalExpression">${input == 3}</conditionExpression>
</sequenceFlow>

3.2 Parallel Gateway

并行网关，可以有多个输入和输出(fork, join or both) ，实现AND逻辑

输入：该网关所有的输入节点都必须完成后才能触发该网关

输出：该网关的所有输出接点都将触发（除非转移条件不通过）

<startEvent id="theStart" />
<sequenceFlow id="flow1" sourceRef="theStart" targetRef="fork" />

<parallelGateway id="fork" />
<sequenceFlow sourceRef="fork" targetRef="receivePayment" />
<sequenceFlow sourceRef="fork" targetRef="shipOrder" />

<userTask id="receivePayment" name="Receive Payment" />
<sequenceFlow sourceRef="receivePayment" targetRef="join" />

<userTask id="shipOrder" name="Ship Order" />
<sequenceFlow sourceRef="shipOrder" targetRef="join" />

<parallelGateway id="join" />
<sequenceFlow sourceRef="join" targetRef="archiveOrder" />

<userTask id="archiveOrder" name="Archive Order" />
<sequenceFlow sourceRef="archiveOrder" targetRef="theEnd" />

<endEvent id="theEnd" />

 3.3 Inclusive Gateway

Inclusive包容网关（Xor输入，And输出）

     输入：只要有一个活动节点到达该网关那么就触发该网关（同XOR输入）

     输出：该网关的所有输出接点都将触发（除非转移条件不通过）同AND输出

<startEvent id="theStart" />
<sequenceFlow id="flow1" sourceRef="theStart" targetRef="fork" />

<inclusiveGateway id="fork" />
<sequenceFlow sourceRef="fork" targetRef="receivePayment" >
  <conditionExpression xsi:type="tFormalExpression">${paymentReceived == false}</conditionExpression>
</sequenceFlow>
<sequenceFlow sourceRef="fork" targetRef="shipOrder" >
  <conditionExpression xsi:type="tFormalExpression">${shipOrder == true}</conditionExpression>
</sequenceFlow>

<userTask id="receivePayment" name="Receive Payment" />
<sequenceFlow sourceRef="receivePayment" targetRef="join" />

<userTask id="shipOrder" name="Ship Order" />
<sequenceFlow sourceRef="shipOrder" targetRef="join" />

<inclusiveGateway id="join" />
<sequenceFlow sourceRef="join" targetRef="archiveOrder" />

<userTask id="archiveOrder" name="Archive Order" />
<sequenceFlow sourceRef="archiveOrder" targetRef="theEnd" />

<endEvent id="theEnd" />

4. TASKS

 4.1 User Task

需要用户参与的任务

humanPerformer 方式，指定一个执行人

<userTask id='theTask' name='important task' >
    <humanPerformer>
      <resourceAssignmentExpression>
        <formalExpression>kermit</formalExpression>
      </resourceAssignmentExpression>
    </humanPerformer>
  </userTask>

potentialOwner 多个人或组

<userTask id='theTask' name='important task' >
    <potentialOwner>
      <resourceAssignmentExpression>
        <formalExpression>user(kermit), group(management)</formalExpression>
      </resourceAssignmentExpression>
    </potentialOwner>
  </userTask>

还有通过属性来设置

• <userTask id="theTask" name="my task" activiti:assignee="kermit" />
• <userTask id="theTask" name="my task" activiti:candidateUsers="kermit, gonzo" />
• <userTask id="theTask" name="my task" activiti:candidateGroups="management, accountancy" />

4.2 Script Task

略

4.3 Java Service Task

4.4 Business Rule Task

业务逻辑任务，使用JBoss Drools 规则引擎来处理输入输出；

<process id="simpleBusinessRuleProcess">

  <startEvent id="theStart" />
  <sequenceFlow sourceRef="theStart" targetRef="businessRuleTask" />

  <businessRuleTask id="businessRuleTask" activiti:ruleVariablesInput="${order}"
      activiti:resultVariable="rulesOutput" />

  <sequenceFlow sourceRef="businessRuleTask" targetRef="theEnd" />

  <endEvent id="theEnd" />

</process>

4.5 Camel Task

camel.apache 规则引擎任务，一个例子

<process id="PingPongProcess">
  <startEvent id="start"/>
  <sequenceFlow id="flow1" sourceRef="start" targetRef="ping"/>
  <serviceTask id="ping" activiti:type="camel"/>
  <sequenceFlow id="flow2" sourceRef="ping" targetRef="saveOutput"/>
  <serviceTask id="saveOutput"  activiti:class="org.activiti.camel.examples.pingPong.SaveOutput" />
  <sequenceFlow id="flow3" sourceRef="saveOutput" targetRef="end"/>
  <endEvent id="end"/>
</process>

org.activiti.camel.examples.pingPong.SaveOutput类

@Override
public void configure() throws Exception {
  from("activiti:PingPongProcess:ping").transform().simple("${property.input} World");
}

测试代码：

@Deployment
public void testPingPong() {
  Map<String, Object> variables = new HashMap<String, Object>();

  variables.put("input", "Hello");
  Map<String, String> outputMap = new HashMap<String, String>();
  variables.put("outputMap", outputMap);

  runtimeService.startProcessInstanceByKey("PingPongProcess", variables);
  assertEquals(1, outputMap.size());
  assertNotNull(outputMap.get("outputValue"));
  assertEquals("Hello World", outputMap.get("outputValue"));
}

5. Sub-Processes and Call Activities 子流程

 子流程是嵌入式的，不可重用，必须从None Start Event开始

而Call Activities本身调用的就是完整的流程

 

7. Process Initiation Authorization 初始化认证

<process id="potentialStarter">
  <extensionElements>
    <activiti:potentialStarter>
       <resourceAssignmentExpression>
         <formalExpression>group2, group(group3), user(user3)</formalExpression>
       </resourceAssignmentExpression>
    </activiti:potentialStarter>
  </extensionElements>

  <startEvent id="theStart"/>
  ...
或
<process id="potentialStarter" activiti:candidateStarterUsers="user1, user2"
                               activiti:candidateStarterGroups="group1">
      ...

8. Data objects 流程数据

<process id="dataObjectScope" name="Data Object Scope" isExecutable="true">
  <dataObject id="dObj123" name="StringTest123" itemSubjectRef="xsd:string">
    <extensionElements>
      <activiti:value>Testing123</activiti:value>
    </extensionElements>
  </dataObject>
  ...

9. Form properties 表单属性

• StartFormData FormService.getStartFormData(String processDefinitionId)
• TaskFormdata FormService.getTaskFormData(String taskId)

<userTask id="task">
  <extensionElements>
    <activiti:formProperty id="room" />
    <activiti:formProperty id="duration" type="long"/>
    <activiti:formProperty id="speaker" variable="SpeakerName" writable="false" />
    <activiti:formProperty id="street" expression="#{address.street}" required="true" />
  </extensionElements>
</userTask>

表单属性 room 对应--〉 流程变量 room 类型： String
表单属性 duration 对应--〉 流程变量 duration 类型： java.lang.Long
表单属性 speaker 对应--〉 流程变量 SpeakerName. 它是TaskFormData对象.
表单属性 street 对应--〉 Java bean 属性 street定义在流程变量 address

<startEvent id="start">
  <extensionElements>
    <activiti:formProperty id="speaker"
      name="Speaker"
      variable="SpeakerName"
      type="string" />

    <activiti:formProperty id="start"
      type="date"
      datePattern="dd-MMM-yyyy" />

    <activiti:formProperty id="direction" type="enum">
      <activiti:value id="left" name="Go Left" />
      <activiti:value id="right" name="Go Right" />
      <activiti:value id="up" name="Go Up" />
      <activiti:value id="down" name="Go Down" />
    </activiti:formProperty>

  </extensionElements>
</startEvent>

<startEvent>
  <extensionElements>
    <activiti:formProperty id="numberOfDays" name="Number of days" value="${numberOfDays}" type="long" required="true"/>
    <activiti:formProperty id="startDate" name="First day of holiday (dd-MM-yyy)" value="${startDate}" datePattern="dd-MM-yyyy hh:mm" type="date" required="true" />
    <activiti:formProperty id="vacationMotivation" name="Motivation" value="${vacationMotivation}" type="string" />
  </extensionElements>
</userTask>

表单：

10. External form rendering 外部表单集成

 提交表单属性，第三方表单系统发送数据：

ProcessInstance FormService.submitStartFormData(String processDefinitionId, Map<String,String> properties)
 
FormService.submitTaskFormData(String taskId, Map<String,String> properties)

获得属性，Acticiti接收处理数据：

• StartFormData FormService.getStartFormData(String processDefinitionId) 
• TaskFormdata FormService.getTaskFormData(String taskId).

关于作者： 王昕（QQ:475660） 在广州工作生活30余年。十多年开发经验，在Java、即时通讯、NoSQL、BPM、大数据等领域较有经验。
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