Book Image

Drools JBoss Rules 5.X Developer's Guide

By : Michal Bali
Book Image

Drools JBoss Rules 5.X Developer's Guide

By: Michal Bali

Overview of this book

<p>Writing business rules has always been a challenging task. Business rules tend to change often leading to a maintenance nightmare. This book shows you various ways to code your business rules using Drools, the open source Business Rules Management System.<br /><br />Drools JBoss Rules 5.X Developer's Guide shows various features of the Drools platform by walking the reader through several real-world examples. Each chapter elaborates on different aspects of the Drools platform. The reader will also learn about the inner workings of Drools and its implementation of the Rete algorithm.<br /><br />The book starts with explaining rule basics, then builds on this information by going through various areas like human readable rules, rules for validation, and stateful rules, using examples from the banking domain. A loan approval process example shows the use of the jBPM module. Parts of a banking fraud detection system are implemented with the Drools Fusion module which is the complex event processing part of Drools. Finally, more technical details are shown detailing the inner workings of Drools, the implementation of the ReteOO algorithm, indexing, node sharing, and partitioning.</p>
Table of Contents (22 chapters)
Drools JBoss Rules 5.X Developer's Guide
Credits
About the Author
About the Reviewers
www.PacktPub.com
Preface
Setting Up the Development Environment
Creating Custom Operators
Dependencies of Sample Application
Index

Getting the data


As a good practice, we'll define an interface for interacting with the other system. We'll introduce a LegacyBankService interface for this purpose. It will make it easier to change the way we communicate with the legacy system, and also the tests will be easier to write.

package droolsbook.transform.service;

import java.util.List;
import java.util.Map;

public interface LegacyBankService {

  /**
   * @return all customers
   */
  List<Map<String, Object>> findAllCustomers();

  /**
   * @return addresses for specified customer id
   */
  List<Map<String, Object>> findAddressByCustomerId(
      Long customerId);

  /**
   * @return accounts for specified customer id
   */
  List<Map<String, Object>> findAccountByCustomerId(
      Long customerId);

}

Code listing 1: Interface that abstracts the legacy system interactions

The interface defines three methods. The first one can retrieve a list of all customers, and the second and third ones...