jbpm 与 工作流模式 多路选择（Multiple Choice）

多路选择（Multiple Choice）

Description A point in the workow process where, based on a decision or workow control
data, a number of branches are chosen.

描述:    在工作流程中某一点,当某一个活动执行结束后,根据一个decision 或者 工作流控制数据, 可以选择一个或多个分支执行.

同义词:Conditional routing, selection, OR-split.

java 代码

/*
 * JBoss, Home of Professional Open Source
 * Copyright 2005, JBoss Inc., and individual contributors as indicated
 * by the @authors tag. See the copyright.txt in the distribution for a
 * full listing of individual contributors.
 *
 * This is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 2.1 of
 * the License, or (at your option) any later version.
 *
 * This software is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this software; if not, write to the Free
 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
 */
package org.jbpm.jpdl.patterns;

import junit.framework.*;

import org.jbpm.context.def.*;
import org.jbpm.context.exe.*;
import org.jbpm.graph.action.Script;
import org.jbpm.graph.def.*;
import org.jbpm.graph.exe.*;
import org.jbpm.graph.node.*;

/**
 * http://is.tm.tue.nl/research/patterns/download/swf/pat_6.swf
 */
public class Wfp06MultiChoiceTest extends TestCase {

  private static ProcessDefinition multiChoiceProcessDefinition = createMultiChoiceProcessDefinition();

  public static ProcessDefinition createMultiChoiceProcessDefinition() {
    ProcessDefinition pd = new ProcessDefinition(
      new String[]{"start-state start",
                   "state a",
                   "fork multichoice",
                   "state b",
                   "state c",
                   "join syncmerge",
                   "end-state end"},
      new String[]{"start --> a",
                   "a --> multichoice",
                   "multichoice --to b--> b",
                   "multichoice --to c--> c",
                   "b --> syncmerge",
                   "c --> syncmerge",
                   "syncmerge --> end"});

    // create the script
    Script script = new Script();
    script.addVariableAccess(new VariableAccess("transitionNames","write",null));
    script.setExpression(
      "transitionNames = new ArrayList();" +
      "if ( scenario == 1 ) {" +
      "  transitionNames.add( \"to b\" );" +
      "} else if ( scenario == 2 ) {" +
      "  transitionNames.add( \"to c\" );" +
      "} else if ( scenario >= 3 ) {" +
      "  transitionNames.add( \"to b\" );" +
      "  transitionNames.add( \"to c\" );" +
      "}" );

    // put the script in the multichoice handler
    Fork fork = (Fork) pd.getNode("multichoice");
    fork.setScript( script );

    pd.addDefinition( new ContextDefinition() );

    return pd;
  }

  public void testMultiChoiceScenario1() {
    ProcessDefinition pd = multiChoiceProcessDefinition;
    Token root = executeScenario(pd, 1);
    Token tokenB = root.getChild("to b"); // the default token names are extracted from the leaving transitions
    Token tokenC = root.getChild("to c"); // the default token names are extracted from the leaving transitions
    assertNotNull( tokenB );
    assertNull( tokenC );
    assertEquals( 1, root.getChildren().size() );
    assertSame( pd.getNode("b"), tokenB.getNode() );
  }

  public void testMultiChoiceScenario2() {
    ProcessDefinition pd = multiChoiceProcessDefinition;
    Token root = executeScenario(pd, 2);
    Token tokenB = root.getChild("to b"); // the default token names are extracted from the leaving transitions
    Token tokenC = root.getChild("to c"); // the default token names are extracted from the leaving transitions
    assertNull( tokenB );
    assertNotNull( tokenC );
    assertEquals( 1, root.getChildren().size() );
    assertSame( pd.getNode("c"), tokenC.getNode() );
  }

  public void testMultiChoiceScenario3() {
    ProcessDefinition pd = multiChoiceProcessDefinition;
    Token root = executeScenario(pd, 3);
    Token tokenB = root.getChild("to b"); // the default token names are extracted from the leaving transitions
    Token tokenC = root.getChild("to c"); // the default token names are extracted from the leaving transitions
    assertNotNull( tokenB );
    assertNotNull( tokenC );
    assertEquals( 2, root.getChildren().size() );
    assertSame( pd.getNode("b"), tokenB.getNode() );
    assertSame( pd.getNode("c"), tokenC.getNode() );
  }

  public static Token executeScenario(ProcessDefinition pd, int scenario) {
    ProcessInstance pi = new ProcessInstance( pd );
    ContextInstance ci = (ContextInstance) pi.getInstance( ContextInstance.class );
    pi.signal();
    Token root = pi.getRootToken();
    assertSame( pd.getNode("a"), root.getNode() );
    ci.setVariable( "scenario", new Integer(scenario) );
    root.signal();
    return root;
  }
}

流程定义文件: 

xml 代码

<process-definition name="process">
    <start-state name='start'>
        <transition to='a' />
    <!---->start-state>
    <state name='a'>
        <transition to='multichoice' />
    <!---->state>
    <fork name='multichoice'>
        <transition name='to b' to='b'>
            <condition>#{scenario == 1} or #{scenario >= 3}<!---->condition>
        <!---->transition>
        <transition name='to c' to='c'>
            <condition>#{scenario == 2} or #{scenario >= 3}<!---->condition>
        <!---->transition>
    <!---->fork>
    <state name='b'>
        <transition to='syncmerge' />
    <!---->state>
    <state name='c'>
        <transition to='syncmerge' />
    <!---->state>
    <join name='syncmerge'>
        <transition to='end' />
    <!---->join>
<!---->process-definition>

testMultiChoiceScenario1()

选择 to_b 路径的情况

节点流程执行顺序

    当scenario == 1

    start --> a --> multichoice --> b --> syncmerge --> end

testMultiChoiceScenario2()


选择 to_c 路径的情况

节点流程执行顺序

    当scenario == 2

    start --> a --> multichoice --> c --> syncmerge --> end

testMultiChoiceScenario3()


选择 to_b,to_c 两个路径的情况

节点流程执行顺序

    当scenario == 3

    start --> a --> multichoice --> b --> syncmerge --> end
                            multichoice --> c  --> syncmerge 

本例中流程以synchronizing Merge结束, 下个例子说明.

评论

6 楼 Bluesnails 2008-02-25  

自己懒得写，搭个顺风车回复一下吧，楼主的xml文件确实有问题（在3.2下，即使增加了end节点，也不正确，condition只有定义在decision内才有意义，而且如果多个转移满足condition条件，只会执行第一个满足条件的转移，所以对于多路转移，目前好像只能使用script，我改写的xml文件如下，已通过验证）

<?xml version="1.0" encoding="UTF-8"?>

<process-definition xmlns="urn:jbpm.org:jpdl-3.2" name="multiChoice">
	<start-state name="start">
		<transition name="" to="a"></transition>
	</start-state>
	<state name="a">
		<event type="node-enter">
			<script>System.out.println("---enter node a--");</script>
		</event>
		<transition name="" to="multichoice"></transition>
	</state>
	<fork name="multichoice">
		<script>

			<variable name="transitionNames" access="write"></variable>
			<expression>
				transitionNames = new ArrayList(); if ( scenario == 1 )
				{ transitionNames.add( "to b" ); } else if ( scenario
				==2 ) { transitionNames.add( "to c" ); } else if
				(scenario >= 3 ) { transitionNames.add( "to b" );
				transitionNames.add( "to c" );}
			</expression>
		</script>
		<event type="node-enter">
			<script>System.out.println("---enter node fork--");</script>
		</event>
		<transition name="to b" to="b"></transition>
		<transition name="to c" to="c"></transition>
	</fork>
	<state name="b">
		<event type="node-enter">
			<script>System.out.println("---enter node b--");</script>
		</event>
		<transition name="" to="syncmerge"></transition>
	</state>
	<state name="c">
		<event type="node-enter">
			<script>System.out.println("---enter node c--");</script>
		</event>
		<transition name="" to="syncmerge"></transition>
	</state>
	<join name="syncmerge">
		<event type="node-enter">
			<script>
				System.out.println("---enter node syncmerge--");
			</script>
		</event>
		<transition name="" to="end"></transition>
	</join>
	<end-state name="end"></end-state>
</process-definition>

5 楼 chinakite 2007-02-07  

<condition>#{scenario == 1} or #{scenario >= 3}</condition>
上面这个表达式中如果==右边是字符串怎么办啊?
我测试的结果是有时好使有时不好使, 很奇怪

4 楼 chenjin 2006-12-04  

代码是有些问题, 我没有测过, 直接评自己的理解写的. jbpm3 还不是很完善. 很多东西在jira上的工作还没有完善. 比如m out of n 只能在代码中设置,  xml schema  没有同步等等.

3 楼 jeffen2006 2006-12-01  

找到原因了，你写的那个xml对应不上源文件的定义，源文件是在fork下定义一个script元素来完成的，而目前的jbpm版本不支持此种类型的持久化，下面是jbpm给出的解释：
the script in a fork is not persisted.  script in fork might be removed in later versions of jPDL

2 楼 jeffen2006 2006-11-30  

你有没有用xml来做过这个流程，我试验了一下，按照你写的xml代码:
testMultiChoiceScenario1()
选择 to_b 路径的情况
当scenario == 1
不是按照：
    start --> a --> multichoice --> b --> syncmerge --> end

而是fork成：
start --> a --> multichoice --> b --> syncmerge
                multichoice --> c
同样你后面的文章也是失败的。
很奇怪，用jbpm的这2个例子junit是成功的。难道ProcessDefinition pd = new ProcessDefinition(  
      new String[],new String[])这种写法和xml定义的不一致。请试验一下。

1 楼 jeffen2006 2006-11-30  

xml 代码少了<end-state name="end"></end-state>