1 Flowable简介
什么是BPMN
先来看下百度百科的定义：
由BPMI(The Business Process Management Initiative)开发了一套标准叫业务流程建模符号(BPMN - Business Process Modeling Notation)。在 BPMI Notation Working Group超过2年的努力，于2004年5月对外发布了BPMN 1.0 规范。后BPMI并入到OMG组织，OMG于2011年推出BPMN2.0标准，对BPMN进行了重新定义**(Business Process Model and Notation**)。BPMN的主要目标是提供一些被所有业务用户容易理解的符号，从创建流程轮廓的业务分析到这些流程的实现，直到最终用户的管理监控。BPMN也支持提供一个内部的模型可以生成可执行的BPEL4WS。因此BPMN的出现，弥补了从业务流程设计到流程开发的间隙。
BPMN定义了一个业务流程图（Business Process Diagram），该业务流程图基于一个流程图（flowcharting），该流程图被设计用于创建业务流程操作的图形化模型。而一个业务流程模型（Business Process Model），指一个由图形对象（graphical objects）组成的网状图，图形对象包括活动（activities)和用于定义这些活动执行顺序的流程控制器（flow controls）。
大白话理解：
BPMN是一套符号的标准，这些符号描述了如果做一个业务，并且这个业务在做的过程中被人监控和控制。业务人员和开发人员通过这套图形可以很好的完成协作。
什么是Flowable
官方描述如下：
Flowable提供了一个组高效的核心开源业务流程引擎，为开发人员，系统管理员和业务用户提供工作流和业务流程管理（BPM）平台。全部用Java编写，并且基于Apache 2.0许可的开源，代码在社区维护。其核心是一个快速，经过试验和测试的动态BPMN流程引擎，附带DMN决策表和CMMN Case管理引擎.
大白话理解：
Flowable是BPMN的一个基于java的软件实现，不过Flowable不仅仅包括BPMN，还有DMN决策表和CMMN Case管理引擎，并且有自己的用户管理、微服务API等一系列功能，是一个服务平台。
Flowable官网、开源社区
Flowable官方网站：
https://www.flowable.org/
Flowable开源代码仓库：
https://github.com/flowable/flowable-engine
Flowable 最新版本(V6.4.0)截止目前下载地址:
Tomcat 版本安装包：
https://download.csdn.net/download/houyj1986/10871025
https://github.com/flowable/flowable-engine/releases/download/flowable-6.4.0/tomcat-flowable-6.4.0.zip
EAR版本版本安装包：
https://download.csdn.net/download/houyj1986/10871018
https://github.com/flowable/flowable-engine/releases/download/flowable-6.4.0/flowable-6.4.0.zip
Flowable源代码（V6.4.0）下载地址：
https://download.csdn.net/download/houyj1986/10871014
Flowable流程示例
一个简单度假申请流程主要过程如下：
1、员工提交请假信息，如工号，请假天数
2、经理点击审批通过或者拒绝
3、如果拒绝直接进入系统发邮件服务通知员工
4、如果通过系统记录该员工的请假天数，减少可用天数
5、员工看到自己请假审批通过，点击完成请假。
Flowable的BPMN流程图: 
流程图的BMPN文件如下:
<?xml version="1.0" encoding="UTF-8"?>
<definitions xmlns="http://www.omg.org/spec/BPMN/20100524/MODEL" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:flowable="http://flowable.org/bpmn" xmlns:bpmndi="http://www.omg.org/spec/BPMN/20100524/DI" xmlns:omgdc="http://www.omg.org/spec/DD/20100524/DC" xmlns:omgdi="http://www.omg.org/spec/DD/20100524/DI" typeLanguage="http://www.w3.org/2001/XMLSchema" expressionLanguage="http://www.w3.org/1999/XPath" targetNamespace="http://www.flowable.org/processdef">
<process id="holidayRequest" name="Holiday Request" isExecutable="true">
<startEvent id="startEvent"></startEvent>
<sequenceFlow id="sequenceFlow-3fa7af74-df9a-4d3a-b0eb-10b20e7dc202" sourceRef="startEvent" targetRef="approveTask"></sequenceFlow>
<userTask id="approveTask" name="经理通过或驳回申请"></userTask>
<sequenceFlow id="sequenceFlow-d9127dc0-158f-4169-b61b-99226ffe8494" sourceRef="approveTask" targetRef="decision"></sequenceFlow>
<exclusiveGateway id="decision"></exclusiveGateway>
<serviceTask id="externalSystemCall" name="系统记录申请天数" flowable:class="org.flowable.CallExternalSystemDelegate"></serviceTask>
<sequenceFlow id="sequenceFlow-6232f578-3975-4d7e-81f2-43b242d33ebd" sourceRef="externalSystemCall" targetRef="holidayApprovedTask"></sequenceFlow>
<userTask id="holidayApprovedTask" name="员工查看申请通过"></userTask>
<sequenceFlow id="sequenceFlow-29fd3375-9bcb-42f2-bb6f-63ae1f98813a" sourceRef="holidayApprovedTask" targetRef="approveEnd"></sequenceFlow>
<serviceTask id="sendRejectionMail" name="发送驳回邮件" flowable:class="org.flowable.SendRejectionMail"></serviceTask>
<sequenceFlow id="sequenceFlow-b390b442-2411-44a9-96eb-3c129d4c8408" sourceRef="sendRejectionMail" targetRef="rejectEnd"></sequenceFlow>
<endEvent id="approveEnd"></endEvent>
<endEvent id="rejectEnd"></endEvent>
<sequenceFlow id="sequenceFlow-6f21d3e2-2e49-4b00-9aae-0b71d861a177" name="驳回" sourceRef="decision" targetRef="sendRejectionMail">
<conditionExpression xsi:type="tFormalExpression"><![CDATA[${!approved}]]></conditionExpression>
</sequenceFlow>
<sequenceFlow id="sequenceFlow-2470619b-fa36-440b-a231-b7bd226c23bb" name="通过" sourceRef="decision" targetRef="externalSystemCall">
<conditionExpression xsi:type="tFormalExpression"><![CDATA[${approved}]]></conditionExpression>
</sequenceFlow>
</process>
<bpmndi:BPMNDiagram id="BPMNDiagram_holidayRequest">
<bpmndi:BPMNPlane bpmnElement="holidayRequest" id="BPMNPlane_holidayRequest">
<bpmndi:BPMNShape bpmnElement="startEvent" id="BPMNShape_startEvent">
<omgdc:Bounds height="30.0" width="30.0" x="0.0" y="95.0"></omgdc:Bounds>
</bpmndi:BPMNShape>
<bpmndi:BPMNShape bpmnElement="approveTask" id="BPMNShape_approveTask">
<omgdc:Bounds height="60.0" width="100.0" x="80.0" y="80.0"></omgdc:Bounds>
</bpmndi:BPMNShape>
<bpmndi:BPMNShape bpmnElement="decision" id="BPMNShape_decision">
<omgdc:Bounds height="40.0" width="40.0" x="230.0" y="90.0"></omgdc:Bounds>
</bpmndi:BPMNShape>
<bpmndi:BPMNShape bpmnElement="externalSystemCall" id="BPMNShape_externalSystemCall">
<omgdc:Bounds height="60.0" width="100.0" x="320.0" y="1.0"></omgdc:Bounds>
</bpmndi:BPMNShape>
<bpmndi:BPMNShape bpmnElement="holidayApprovedTask" id="BPMNShape_holidayApprovedTask">
<omgdc:Bounds height="60.0" width="100.0" x="470.0" y="1.0"></omgdc:Bounds>
</bpmndi:BPMNShape>
<bpmndi:BPMNShape bpmnElement="sendRejectionMail" id="BPMNShape_sendRejectionMail">
<omgdc:Bounds height="60.0" width="100.0" x="320.0" y="160.0"></omgdc:Bounds>
</bpmndi:BPMNShape>
<bpmndi:BPMNShape bpmnElement="approveEnd" id="BPMNShape_approveEnd">
<omgdc:Bounds height="28.0" width="28.0" x="620.0" y="16.0"></omgdc:Bounds>
</bpmndi:BPMNShape>
<bpmndi:BPMNShape bpmnElement="rejectEnd" id="BPMNShape_rejectEnd">
<omgdc:Bounds height="28.0" width="28.0" x="505.0" y="175.0"></omgdc:Bounds>
</bpmndi:BPMNShape>
<bpmndi:BPMNEdge bpmnElement="sequenceFlow-2470619b-fa36-440b-a231-b7bd226c23bb" id="BPMNEdge_sequenceFlow-2470619b-fa36-440b-a231-b7bd226c23bb">
<omgdi:waypoint x="250.0" y="90.0"></omgdi:waypoint>
<omgdi:waypoint x="250.0" y="31.0"></omgdi:waypoint>
<omgdi:waypoint x="319.99999999999284" y="31.0"></omgdi:waypoint>
</bpmndi:BPMNEdge>
<bpmndi:BPMNEdge bpmnElement="sequenceFlow-3fa7af74-df9a-4d3a-b0eb-10b20e7dc202" id="BPMNEdge_sequenceFlow-3fa7af74-df9a-4d3a-b0eb-10b20e7dc202">
<omgdi:waypoint x="29.949998618355412" y="110.0"></omgdi:waypoint>
<omgdi:waypoint x="80.0" y="110.0"></omgdi:waypoint>
</bpmndi:BPMNEdge>
<bpmndi:BPMNEdge bpmnElement="sequenceFlow-6232f578-3975-4d7e-81f2-43b242d33ebd" id="BPMNEdge_sequenceFlow-6232f578-3975-4d7e-81f2-43b242d33ebd">
<omgdi:waypoint x="419.95000000000005" y="31.0"></omgdi:waypoint>
<omgdi:waypoint x="470.0" y="31.0"></omgdi:waypoint>
</bpmndi:BPMNEdge>
<bpmndi:BPMNEdge bpmnElement="sequenceFlow-b390b442-2411-44a9-96eb-3c129d4c8408" id="BPMNEdge_sequenceFlow-b390b442-2411-44a9-96eb-3c129d4c8408">
<omgdi:waypoint x="419.949999999997" y="189.66442953020135"></omgdi:waypoint>
<omgdi:waypoint x="505.00030595247523" y="189.0936221647077"></omgdi:waypoint>
</bpmndi:BPMNEdge>
<bpmndi:BPMNEdge bpmnElement="sequenceFlow-d9127dc0-158f-4169-b61b-99226ffe8494" id="BPMNEdge_sequenceFlow-d9127dc0-158f-4169-b61b-99226ffe8494">
<omgdi:waypoint x="179.9499999999898" y="110.0"></omgdi:waypoint>
<omgdi:waypoint x="230.0" y="110.0"></omgdi:waypoint>
</bpmndi:BPMNEdge>
<bpmndi:BPMNEdge bpmnElement="sequenceFlow-29fd3375-9bcb-42f2-bb6f-63ae1f98813a" id="BPMNEdge_sequenceFlow-29fd3375-9bcb-42f2-bb6f-63ae1f98813a">
<omgdi:waypoint x="569.9499999999988" y="31.0"></omgdi:waypoint>
<omgdi:waypoint x="582.0" y="31.0"></omgdi:waypoint>
<omgdi:waypoint x="582.0" y="31.0"></omgdi:waypoint>
<omgdi:waypoint x="620.0025321198765" y="30.268220825690175"></omgdi:waypoint>
</bpmndi:BPMNEdge>
<bpmndi:BPMNEdge bpmnElement="sequenceFlow-6f21d3e2-2e49-4b00-9aae-0b71d861a177" id="BPMNEdge_sequenceFlow-6f21d3e2-2e49-4b00-9aae-0b71d861a177">
<omgdi:waypoint x="250.0" y="129.9375468164794"></omgdi:waypoint>
<omgdi:waypoint x="250.0" y="190.0"></omgdi:waypoint>
<omgdi:waypoint x="319.99999999997794" y="190.0"></omgdi:waypoint>
</bpmndi:BPMNEdge>
</bpmndi:BPMNPlane>
</bpmndi:BPMNDiagram>
</definitions>
文件名为Holiday_Request.bpmn20.xml，flowable支持以BPMN和bpmn20.xml结尾的流程文件。上面的xml看起来非常恐怖，不用担心，后面我会介绍Flowable的专门的流程绘制软件。
以上主要让大家对Flowable有个简单的了解，下一节介绍如何启动Flowable，并且介绍Flowable的启动包的相关内容。
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