Activiti in Action

Tijs Rademakers

• Editore: Manning Publications
• Anno: 2012
• ISBN:
  9781617290121
• Argomento: Computer Science
• Categoria: Project Management

Activiti in Action is a comprehensive tutorial designed to introduce developers to the world of business process modeling using Activiti. Before diving into the nuts and bolts of Activiti, this book presents a solid introduction to BPMN 2.0 from a developer's perspective.

Part 1. Introducing BPMN 2.0 and Activiti

This first part of the book provides an introduction to the Activiti framework and the background about the BPMN 2.0 standard. In chapter 1, we’ll cover how to set up an Activiti environment, starting with the download of the Activiti framework. In chapter 2, you’ll be introduced to the main elements of the BPMN 2.0 standard in order to create process definitions. Chapter 3 offers an overview of the Activiti framework’s main components, including the Activiti Designer and Explorer. Finally, in chapter 4, we’ll discuss the Activiti API with several short code examples.

Chapter 1. Introducing the Activiti framework

This chapter covers

• Introduction to Activiti
• Installing the Activiti framework
• Implementing a BPMN 2.0 process

Every day, your actions are part of different processes. For example, when you order a book in an online bookstore, a process is executed to get the book paid for, packaged, and shipped to you. When you need to renew your driver’s license, the renewal process often requires a new photograph as input. Activiti provides an open source framework to design, implement, and run processes. Organizations can use Activiti to implement their business processes without the need for expensive software licenses.

This chapter will get you up and running with Activiti in 30 minutes. First, we’ll take a look at the different components of the Activiti tool stack, including a Modeler, Designer, and a REST web application. Then, we’ll discuss the history of the Activiti framework and compare its functionality with its main competitors, jBPM and BonitaSoft.

Before we dive into code examples in section 1.4, we’ll first make sure the Activiti framework is installed correctly. At the end of this chapter, you’ll have a running Activiti environment and a deployable example.

First, let’s look at Activiti’s tool stack and its different components, including the modeling environment, the engine, and the runtime explorer application.

1.1. The Activiti tool stack

The core component of the Activiti framework is the process engine. The process engine provides the core capabilities to execute Business Process Model and Notation (BPMN) 2.0 processes and create new workflow tasks, among other things. You can find the BPMN specification and lots of examples at www.bpmn.org, and we’ll go into more detail about BPMN in chapter 2. The Activiti project contains a couple of tools in addition to the Activiti Engine. Figure 1.1 shows an overview of the full Activiti tool stack.

Figure 1.1. An overview of the Activiti tool stack: in the center, the Activiti process engine, and on the right and left sides, the accompanying modeling, design, and management tools. The grayed-out components are add-ons to the core Activiti framework.

Let’s quickly walk through the different components listed in figure 1.1. With the Activiti Modeler, business and information analysts are capable of modeling a BPMN 2.0-compliant business process in a web browser. This means that business processes can easily be shared—no client software is needed before you can start modeling. The Activiti designer is an Eclipse-based plugin, which enables a developer to enhance the modeled business process into a BPMN 2.0 process that can be executed on the Activiti process engine. You can also run unit tests, add Java logic, and create deployment artifacts with the Activiti Designer.

In addition to the design tools, Activiti provides a number of supporting tools. With Activiti Explorer, you can get an overview of deployed processes and even dive into the database tables underneath the Activiti process engine. You can also use Activiti Explorer to interact with the deployed business processes. For example, you can get a list of tasks that are already assigned to you. You can also start a new process instance and look at the status of that newly created process instance in a graphical diagram.

Finally, there’s the Activiti REST component, which provides a web application that starts the Activiti process engine when the web application is started. In addition, it offers a REST API that enables you to communicate remotely with the Activiti Engine.

The different components are summarized in table 1.1.

Table 1.1. An overview of the different components of the Activiti tool stack

Component name	Short description
Activiti Engine	The core component of the Activiti tool stack that performs the process engine functions, such as executing BPMN 2.0 business processes and creating workflow tasks.
Activiti Modeler	A web-based modeling environment for creating BPMN 2.0-compliant business process diagrams. This component is donated by Signavio, which also provides a commercial modeling tool, named the Signavio Process Editor.
Activiti Designer	An Eclipse plugin that can be used to design BPMN 2.0-compliant business processes with the addition of Activiti extensions, such as a Java service task and execution listeners. You can also unit test processes, import BPMN 2.0 processes, and create deployment artifacts.
Activiti Explorer	A web application that can be used for a wide range of functions in conjunction with the Activiti Engine. You can, for example, start new process instances and get a list of tasks assigned to you. In addition, you can perform simple process management tasks, like deploying new processes and retrieving the process instance status.
Activiti REST	A web application that provides a REST interface on top of the Activiti Engine. In the default installation (see section 1.1.3), the Activiti REST application is the entry point to the Activiti Engine.

You can’t start developing without a clear understanding of the Activiti framework and the architecture that’s built around a state machine. Let’s take a closer look at the history of the Activiti framework and discuss the Activiti Engine in more detail.

1.2. Getting to know Activiti

When you start working with a new framework, it’s always good to know some project background and have an understanding of the main components. In this section, we’ll be looking at exactly that.

1.2.1. A little bit of history

The Activiti project was started in 2010 by Tom Baeyens and Joram Barrez, the former founder and the core developer of jBPM (JBoss BPM), respectively. The goal of the Activiti project is to build a rock-solid open source BPMN 2.0 process engine. In the next chapter, we’ll talk in detail about the BPMN 2.0 specification, but in this chapter we’ll focus on the Activiti framework itself and getting it installed and up and running with simple examples.

Activiti is ...