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

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本文详细介绍了BPMN2.0的核心概念，包括事件、顺序流、网关、任务等，并深入探讨了如何利用这些概念设计流程。同时，文章还介绍了流程初始化认证、流程数据及表单属性等内容。

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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

在确切的时间点执行

timeDuration

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。

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：

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：