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Chapter 1. Introduction

Eric5231 — Sun, 03 Feb 2008 06:33:00 GMT

1.Overview

    JBoss jBPM is a flexible, extensible framework for process languages.
    jPDL is one process language that is build on top of that common framework. It has serval advantages:
        1.It is an intuitive process language to express business processes graphically in terms of tasks, wait states for asynchronous communication, timers, automated actions,... To         bind these operations together;
        2.jPDL has minimal dependencies and can be used as easy as using a java library;
        3.it can also be used in environments where extreme throughput is crucial by deploying it on a J2EE clustered application server;

2.The jPDL Kits

The starter kit is a download that contains all the jBPM components bundled in one easy download. The download includes:

runtime, the core jbpm component including the libs and this userguide.
server, a preconfigured jboss application server.
designer, the eclipse plugin for authoring jBPM processes graphically.
db, the jBPM database compatibility package (see below).
bpel, a reference to the JBoss jBPM BPEL extension.

3. Advantages of JBOSS JBPM

    3.1   The JBOSS jBPM has a graphical process designer, which can as a n eclipse plugin;
    3.2   The JBOSS jBPM core componet is based on J2SE, so it can be used in any java environment like e.g. a webapplication, a swing application, an EJB, a
            webservice...;
    3.3 The JBOSS jBPM console web application supplys a central user interface for interacting with runtime tasks generated by the process executions, and
            administration and monitoring console to inspect and manipulate runtime instance;
    3.4   The JBoss jBPM identity component;
    3.5   The JBoss jBPM scheduler monitors and executes timers that are scheduled during process executions(Configuring the scheduler servlet to spawn the monitoring thread or Starting up a separate JVM with the scheduler main);
    3.6   The JBoss jBPM database compatibility package;
    3.7   The JBoss jBPM BPEL extension is a separatly packaged extension that extends jBPM with support for BPEL;

Eric5231 2008-02-03 14:33 发表评论

jBPM开发入门指南(2)(转)

Eric5231 — Fri, 01 Feb 2008 03:47:00 GMT

jBPM开发入门指南(2)

4 数据库初始化

jBPM 需要数据库支持， jBPM 会把自己的一个初始化数据存储到数据库，同时工作流的数据也是存储到数据库中的。 jBPM 使用 Hibernate 来做为自己的存储层，因此只要是 Hibernate 支持的数据库， jBPM 也就支持。

本文先以 MySQL 为例，然后再以 Oracle 为例，来谈谈 jBPM 的数据库初始化操作。

注：在上面的 JBoss 自带的示例中，并没有设置数据库，那是因为 jBPM 默认使用的是内存数据库 hsqldb 。

4.1 MySQL

1 、首先安装 MySQL 。

MySQL 的安装比较简单，网上也有很多文章，本文不再赘述。本指南所用 MySQL 版本为 MySQL 4.1 （ for windows ）。再找一个 MySQL 客户端，目的是方便查看数据库中的数据，本文推荐使用 MySQL 网站上免费提供的“ MySQL Query Brower ”，当然你用其他的客户端也行，比如 MySQL-Front 。

2 、建库

MySQL 中创建一个库，库名： jbpm

3 、生成建表的 SQL 语句并建表

将 jbpm-starters-kit-3.1.1 下的子目录 jbpm 改名为 jbpm.3 ，否则在执行下面的 ant 命令时会报如 jbpm.3 目录不存在的错误：

D:\jbpm-starters-kit-3.1.1\jbpm-db\build.xml:361: The following error occurred while executing this line:

D:\jbpm-starters-kit-3.1.1\jbpm-db\build.xml:68: Basedir D:\jbpm-starters-kit-3.1.1\jbpm.3 does not exist

在 DOS 窗下，进入 D:\jbpm-starters-kit-3.1.1\jbpm-db 目录，执行如下命令：

ant mysql.scripts

执行成功后，在 D:\jbpm-starters-kit-3.1.1\jbpm-db\build\mysql\scripts 目录里生成了四个 sql 文件，它们做什么用的一看名字就知道了。在 MySQL 客户端中执行“ mysql.create.sql ”脚本，这样将在 jbpm 库中创建一个个的数据表。

4.2 Oracle

先安装好 Oracle 服务器。我们公司有现存的 Oracle 服务器，也提供给了我一个属于我自己的用户名，一登录就可以任意在我的库之下创建表了。所以这一步就省了，没有的自个先装好吧。

访问 Oracle 推荐用“ PLSQL Developer ”。不过要连接 Oracle 还要在本机上装上 Oracle 自己的客户端程序，里面提供了 JDBC 包和一些配置。要连接服务器还得配置一下，我一般都是不用 GUI 而直接改 tnsnames.ora 文件，在我的电脑里此文件的目录地址是： D:\oracle\ora92\network\ADMIN\tnsnames.ora ，内容如下 ( 两面有两个配置了 ) ：

# TNSNAMES.ORA Network Configuration File: E:\oracle\ora92\network\admin\tnsnames.ora

# Generated by Oracle configuration tools.

WXXRDB_192.168.3.2 =

(DESCRIPTION =

(ADDRESS_LIST =

(ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.3.2)(PORT = 1521))

)

(CONNECT_DATA =

(SID = wxxrDB)

(SERVER = DEDICATED)

)

WXXRDB_192.168.4.2 =

(DESCRIPTION =

(ADDRESS_LIST =

(ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.4.2)(PORT = 1521))

)

(CONNECT_DATA =

(SID = wxxrDB)

(SERVER = DEDICATED)

)

前面都是 Oracle 的一些知识，不会的 Google 一下吧。最后配置好后，用 PLSQL Developer 输入你的用户名和密码联接到 Oracle ，就算 OK 了。

参考上面 MySQL 的步骤，基本一样：

（1）将 jbpm 改名为 jbpm.3

（2）再执行 ant oracle.scripts

（3）用 jbpm-db\build\oracle\scripts 目录的 oracle.create.sql 脚本，在 Oracle 中生成 jBPM 的所有表。在“ PLSQL Developer ”中可以新建一个 Command Windows 窗口然后输入命令： @D:\jbpm-starters-kit-3.1.1\jbpm-db\build\oracle\scripts\oracle.create.sql

Eric5231 2008-02-01 11:47 发表评论

jBPM开发入门指南(1)(转)

Eric5231 — Fri, 01 Feb 2008 03:43:00 GMT

jBPM开发入门指南(1)

工作流虽然还在不成熟的发展阶段，甚至还没有一个公认的规范标准。但其应用却已经在快速展开，这说明市场对工作流框架的需求是急迫而巨大的。

jBPM 的正处在不断发展中，做为开源软件的特点，其设计变化往往很大。所以一些过去的资料可能已经不适用了。于是作者根据自己的使用经验，重新整理出这份文档，以备学习参考。

注：本文使用的 jBPM 版本为 3.1.1

环境准备

1、安装JDK

所有 JAVA 开发第一个需要安装的，没什么好说的。记得把系统变量 JAVA_HOME 设上。

2、安装Ant

Ant 是使用 jBPM 必须的一个工具。 jBPM 中的很多操作都要用到 Ant 。

安装方法：

（ 1 ）先下载： http://archive.apache.org/dist/ant/binaries/ ，选一个如： apache-ant-1.6.5-bin.zip 。

（ 2 ）解压到 D:\ant （当然其他目录也可以）。

（ 3 ）设置如下系统变量： ANT_HOME=d:\ant 。

（ 4 ）把 %ANT_HOME%\bin 加入到系统变量 PATH 中。

3、安装Eclipse

Eclipse 不是开发 jBPM 必须的工具，但它是对 jBPM 开发很有帮助的工具，特别是 jBPM 提供了一个 Eclipse 插件用来辅助开发 jBPM 。关于 Eclipse 的安装不赘述了，本文用的版本是： Eclipse3.2

安装 jBPM

jBPM 的下载地址： http://www.jboss.com/products/jbpm/downloads 　

l JBoss jBPM 是 jBPM 的软件包

l JBoss jBPM Starters Kit 　是一个综合包，它包括了 jBPM 软件包、开发插件、一个配置好了的基于 JBoss 的 jBPM 示例、一些数据库配置文件示例。

l JBoss jBPM Process Designer Plugin 　是辅助开发 jBPM 的 Eclipse 插件。

l JBoss jBPM BPEL Extension jBPM 关于 BPEL 的扩展包

本指南选择下载： JBoss jBPM Starters Kit 。下载后解压到 D:\jbpm-starters-kit-3.1 ，目录下含有五个子目录：

l jbpm 　 jBPM 的软件包

l jbpm-bpel 只含有一个网页

l jbpm-db 各种数据库 hibernate 配置文件示例，有些还包含了相应的 jdbc 驱动程序。

l jbpm-designer 　辅助开发 jBPM 的 Eclipse 插件，具体在 jbpm-gpd-feature 子目录中

l jbpm-server 　一个已经配置好了的基于 JBoss 的 jBPM 示例 .

感觉下工作流

前面我们说了，在 JBoss jBPM Starters Kit 的 jbpm-server 目录是一个已经配置好的了 jBPM 示例，那么让我们来感觉一下 jBPM 做出的东西吧。

双击 jbpm-server 目录下的 start.bat 文件，启动 JBoss 服务。这时会打开一个 DOS 窗口，启动完成后，日志会不断输出，其中最后一句是“ 13:55:39,937 DEBUG [StaticNotifier] going to wait for (CMD_EXECUTOR, java.lang.Object@1df59bd) ”，这表示 jBPM 在开始工作了，它不断进行轮询。

打开网页： http://localhost:8080/jbpm/ 　得到如下画面

这是一个已经用 jBPM 开发好的用户定单流程，具有下单、审核、估价等流程。它所用的数据库是一个内置的数据库。

以 cookie monster 用户登录，选择“ create new web sale order ”可以创建一个定单。如下图所示，在图左边是填写的定单情况，右边一整个定货流程的示意图，红色框表示流程进行到哪一步了。填写好定单好，选择“ Save and Close Task ”，完成定单提交。

选择右上角的“ Login as another user ”以另外一个用户名 ernie 登录。这时可以看到 ernie 用户的任务列表中多了一项。

点进去后，显示如下画面。这个示例对中文的支持不好，全都显示成了 unicode 码了。不管这什么多，反正知道是这么回事就行了。在 comment 项填写意见，选 OK 按钮，进入到下一步。如果选择 more info needed 按钮，则打回给 cookie monster 用户修改定单。

下面的流程，这里就不再赘述了。在这个很标准的工作流示例中，我们基本可以看到 jBPM 的应用范围还是比较广的。而且从这个示例，我们是看不出有 jBPM 的，也就是说 jBPM 在后台起着作用。

从这个例子，还看不出 jBPM 的优势。不过，如果在一个流程不确定，经常需要变动的项目中， jBPM 的好处将会显然出来。应用 jBPM 后，改变流程只需改变流程描述文件，这将在后面的内容提到。

这是一个已做好的示例，接下来我们将仿造这个实例来开发一个请假流程。

Eric5231 2008-02-01 11:43 发表评论

JBoss jBPM 2.0 Tutorial

Eric5231 — Fri, 01 Feb 2008 03:37:00 GMT

JBPM is a workflow management system (WFMS). The next image shows the interfaces between jBpm and all actors involved in the form of a use case diagram.

Since the term workflow mangament system has a complete different meaning to different people, I will explain the core responsabilities of a workflow management system in four layers. A more detailed description of the 4 layers can be found in the article The State of Workflow.

jBpm takes process archives as input. A process archive is a formal description of a business process. After a process archive is deployed, jBpm can manage the executions of this process. 'Managing the executions' means keeping track of the state of a process (State layer), storing information associated with a process execution (Context layer), integrating custom programming logic like e.g. sending emails, interacting with an ERP, ... (Programming logic layer) and optionally allow users to complete tasks by submitting forms (User interfaces layer).

Main responsibility

The main responsibility of a WFMS is to maintain the state of process executions. The state model of jBpm is based on a graph with nodes and transitions. Nodes and transitions are the main ingredients of a process definition. A state is an example of a node.

Runtime interaction

The 2 most important interactions with jBpm are : starting one instance (=one execution) of a process definition and signalling the end of a state. As a result of both these interactions jBpm will calculate the next state of the process instance.

Actions

The state graph, provides the structure of the process. Actions are pieces of programming logic that can be executed upon events in the process. There are three types of events : entering a node, leaving a node and taking a transition. While jBpm is calculating the next state, a number of these events will fire.

Process archives

The main file in a process archive is processdefinition.xml. That file contains the formal description of the process. The act of parsing the processdefinition.xml and storing it in the database is called deploying a process. All other files in a process archive are stored as attachments with the process definition (either in the database or as files on the filesystem).

Example

Create a process archive

We have modelled the following process for requesting a pay raise...

The payraise process This process is expressed as xml like this:

1 xml version="1.0" encoding="UTF-8"?>
2 DOCTYPE process-definition PUBLIC
3     "-//jBpm/jBpm Mapping DTD 2.0//EN"
4     "http://jbpm.org/dtd/processdefinition-2.0.dtd">
5
6 <process-definition name="pay raise process">
7
8
9   <start-state name="request a payraise" >
10     <transition to="evaluating"/>
11   start-state>
12
13
14   <state name="evaluating">
15
16     <transition name="approve"     to="fork"/>
17     <transition name="disapprove"  to="done"/>
18   state>
19
20   <fork name="fork">
21     <transition to="updating erp asynchronously" />
22     <transition to="treating collegues on cake and pie" />
23   fork>
24
25   <state name="updating erp asynchronously">
26
27     <transition to="join" />
28   state>
29
30   <state name="treating collegues on cake and pie">
31
32     <transition to="join" />
33   state>
34
35   <join name="join">
36     <transition to="done" />
37   join>
38
39
40   <end-state name="done" />
41
42 process-definition>

snippet of the processdefinition.xml

Deploy process archive

jBpm store its process definitions in the database. So deploying a process into jbpm actually means parsing the processdefinition.xml and store it in the jbpm database. This can be done in one of 2 ways:

the jbpm ant-tasks par and deploypar. par lets you create a process archive from a set of files. deploypar deploys a process archive to the database. The deploypar takes a jbpm.properties file as an attribute. That file specifies the jbpm configurations including the database to which the process archive has to be deployed. For more information about the properties, see configuration.
programmatically like this:

1 // create a process archive input stream
2 String resource = "payraise/processdefinition.xml";
3 InputStream is = PayRaiseTest
4                    .class
5                    .getClassLoader()
6                    .getResourceAsStream(resource);
7 ArchiveBuilder ab = new ArchiveBuilder(is);
8 JarInputStream jis = ab.getJarInputStream();
9
10 // deploy the process
11 DefinitionService ds = JbpmServiceFactory
12                          .getInstance()
13                          .openDefinitionService();
14 ds.deployProcessArchive(jis);
15 ds.close();

code to deploy a process archive
Note that also this code uses the jbpm.properties for its configuration, including the database to which the process archive is deployed.

Note that the jbpm default configurations points to an hypersonic in-memory database. That is ideal for testing. But this is of little use when using the ant task to deploy your process. In that case, your database will live in the runtime memory of the ant-task so you'll not be able to access it after the ant-task has completed.

Start process instance

After packing and deploying this process to the jBpm database, the next code example shows how to start a process instance.

1 ExecutionService executionService =
2 JbpmServiceFactory.getInstance().openExecutionService("AlbertEinstein");
3 executionService.startProcessInstance( "payraise" );
4 executionService.close();

code to start a process instance

Getting a task list

A token is a pointer to a state. In jbpm, every token can point to one actor, thereby creating a relation between a state and an actor. The idea behind this state-actor relation in a token. is the following : when workflow engine enters a state, that means that the workflow engine will be waiting for some external trigger. If the process definition is equipped with a calculation that determines *who* it is waiting for, this calculation is executed when the token enters the state. So the task list will be a collection of tokens that refer to a given actor. Actors in jBpm are always referenced by their id : actorId (java.lang.String).

1 // get an execution service for user Carl Gauss (cg)
2 ExecutionService executionService = JbpmServiceFactory.getInstance().openExecutionService("cg");
3 // get the task list for Carl Gauss (cg)
4 Collection tasks = executionService.getTaskList("cg");
5 executionService.close();

code to get a tasklist

Signal the end of a state

When the process instances was started, jBpm calculated that the next state is 'evaluating' and that user CarlGauss is responsible for this task. This resulted in the token of the process being assigned to 'CarlGauss'. The next snippet asks jBpm all the tokens that are waiting for CarlGauss. In this example we assume that the first task is the one we started above. When CarlGauss has made his decision, he informs jBpm by means of the endOfState method call. Note that in this example we explicitly provide the name of the leaving transition to indicate the choice made by the user.

1 ExecutionService executionService =
2 JbpmServiceFactory.getInstance().openExecutionService("CarlGauss");
3 Collection tasks = executionService.getTaskList("CarlGauss");
4 Token token = (Token) tasks.iterator().next();
5 executionService.endOfState( token.getId(), "approve" );
6 executionService.close();

code to signal an end of state

Eric5231 2008-02-01 11:37 发表评论