Chapter 2. Writing and Executing Rules

The best way to learn something new is by trying it out. For this reason, in this chapter, we are going to cut to the chase to write and execute our first rules. We will also cover the most important points about the rule language and how to effectively write rules that mean something to your domain. This chapter will use the eShop model introduced in the previous chapter to demonstrate a set of scenarios where rules can be applied.

Before we start coding, in the first half of this chapter, you will learn how to set up all the standard tools required to work with Drools and the examples provided with this book. We will be creating a project from scratch, therefore, you can use this chapter as a reference to start your applications from the ground up. The second half of the chapter will cover the introduction to the DRL language and how we recommend to organize your projects when you are using rules or other knowledge assets such as business processes.

Briefing this up, this chapter we will cover the following topics:

• Setting up our environment
• Creating our first Drools project
• Writing and executing our first rule
• Discussing the DRL rule language
• Organizing our projects