Java Version 1.5+ is required to run examples in this book. Drools can be downloaded from http://www.jboss.org/drools/downloads.html. You'll need the Drools (drools-distribution-5.5.0.Final.zip) and Drools and jBPM tools (droolsjbpm-tools-distribution-5.5.0.Final.zip) downloads. The former is the rule engine itself, that is, the binaries. The latter is the Drools Eclipse plugin. It greatly helps at writing rules. The Drools new project wizard in Eclipse can create a simple Drools project that is ready to run. When setting it up, you need to tell it the location of Drools Runtime (where you extracted the Drools binaries).

Next, you'll also need to download jBPM. Go to http://www.jboss.org/jbpm/ and select the Downloads link. From there go to jBPM 5 | jbpm-5.4.0.Final and download the jbpm-5.4.0.Final-bin.zip file. Similar to setting up the Drools runtime, we'll set up jBPM Runtime inside Eclipse.

If for some reason the Eclipse plugin is not an option, Drools can be set up by maven or manually. When using maven, add at least the following dependencies to your project's pom.xml file:

<dependencies>
  <dependency>
    <groupId>org.drools</groupId>
    <artifactId>knowledge-api</artifactId>
    <version>${drools.version}</version>  
  </dependency>
  <dependency>
    <groupId>org.drools</groupId>
    <artifactId>drools-core</artifactId>
    <version>${drools.version}</version>  
  </dependency>
  <dependency>
    <groupId>org.drools</groupId>
    <artifactId>drools-compiler</artifactId>
    <version>${drools.version}</version>  
  </dependency> 
  <dependency>
    <groupId>org.jbpm</groupId>
    <artifactId>jbpm-flow</artifactId>
    <version>${jbpm.version}</version>
  </dependency>
  <dependency>
    <groupId>org.jbpm</groupId>
    <artifactId>jbpm-flow-builder</artifactId>
    <version>${jbpm.version}</version>
  </dependency>  
  <dependency>
    <groupId>org.jbpm</groupId>
    <artifactId>jbpm-bpmn2</artifactId>
    <version>${jbpm.version}</version>
  </dependency>
</dependencies>
<properties>
  <drools.version>5.5.0.Final</drools.version>
  <jbpm.version>5.4.0.Final</jbpm.version>
</properties>

Code listing 1: Drools and jBPM dependencies in a maven's pom.xml file

By adding these dependencies into the project's pom file, we're declaring that our project depends on the Drools libraries such as knowledge-api, drools-code, and drools-compiler and the jBPM libraries such as jbpm-flow, jbpm-flow-builder, and jbpm-bpmn2. Depending on the features used, we may need to add or remove other Drools/jBPM libraries. Please note the drools.version property that is set to Version 5.5.0.Final. You may need to change it depending on the latest release available. The same applies to the jBPM version property.

We may also need to tell maven where to get these libraries. They can be downloaded from the official JBoss maven repository, which is located at https://repository.jboss.org/nexus/content/repositories/releases/. The following code snippet does the trick:

<repositories>
  <repository>
    <id>JBoss Repository</id>
    <url>https://repository.jboss.org/nexus/content/repositories/releases/</url>
    <snapshots>
      <enabled>false</enabled>
    </snapshots>
    <releases>
      <enabled>true</enabled>
    </releases>
  </repository>
</repositories>   

Code listing 2: JBoss maven repository in a maven's pom.xml file

Note that the latest snapshot releases can be downloaded from https://repository.jboss.org/nexus/content/repositories/snapshots/.

Let's now look at libraries that are needed in more detail.