Jess in Action: Rule-Based Systems in Java

Rating:
Summary: Necessity for any Jess developer
Review: Author is the creator of Jess. The book is as well put together as the product itself. It doesn't assume any jess (or rules) expertise, and doesn't drag on with details you wont care about. Concisely covers the essential basics and moves on to non-trivial examples. As you follow the lead of the author in these examples you don't just understand the workings of jess, but also develop the thought process required to design rules based applications.

Time well invested.

Rating:
Summary: Waited a long time, and my patience was rewarded
Review: I see two ways to avoid writing a hard-to-use book about a complex product: one, write a book you wish existed when needed it. Or, if you've brought something new to the world, write about it so that anyone could understand what it does and how it works. I think Friedman-Hill has managed exactly that.

It's not easy for an expert to discuss the fundamentals of a creation as if it was altogether new, but Friedman-Hill manages this with good humor, a light touch, and most importantly a natural ability to describe how using rules-based engines can provide real power to the program designer.

As both guide and reference, this book has helped me apply Jess and reinforce my understanding of other ways to take advantage of it. When I first came across the website for Jess years ago, there wasn't enough context there for me to figure out where to start. With this book in hand I wrote some prototypes, learned how the engine worked, and started looking for effective ways to incorporate this tool into other tasks.

This book is best used by a self-starting, proficient programmer who is looking for powerful ways to tackle complex problems. For those who might need more motivation to invest their time, you'll just have to work a little harder. This is the only book available on the subject, and while the explanations run smoothly, feeling comfortable with Jess will take some time. That said, you should do it; you'll (eventually) be glad you did.

This is a fine book; I rate it 4 stars because it's the only book available on the subject. It's clear, well-written, informative, and entertaining -- for a nerd, anyway -- but I like to believe there's room to improve on it, and maybe even room for a "best" book. Nonetheless, your money will certainly be well-spent right here.

Rating:
Summary: Excellent intro to rules and Jess, plus fun to boot
Review: Jess in Action presents the Jess rule-based framework, and explores it through four meaty and well-chosen examples: a console tax forms advisor, a console PC repair assistant, a Swing HVAC controller, and a servlet-based purchasing agent. The examples vary greatly in their designs and styles of interaction between Jess and Java, and expose patterns in a concrete context. It's especially nice the way each example builds on the functionality of the one before, such as a text-based question/interview module that is extended into a Swing GUI.

The book starts with an introduction to rule-based systems, goes through the basics of the Jess language, and then dives into the examples; the appendices include API references to both Jess functions and Jess's Java APIs, and numerous links and references are scattered throughout the book. If I have any complaint about the organization, it's that the book could have been even more example-driven, abandoning (or shortening) the chapter on syntax and basic functions and introducing them only when used in an example; the rest could have been left to the appendix of Jess functions.

The book is interesting and readable but dense with concepts, so its only 388 pages of content and 50 pages of appendices will take some (well-spent) time to get through. A second skimming impressed me anew with the richness of the material, and the productive way in which it's presented, so I recommend reading the book once to get the overall feel, and then going through it again with the working Jess command shell, editor, and command line in front of you. Or an IDE if you must. :-)

Jess itself consists of a rule language, a runtime engine which supports forward and limited backward-chaining, and APIs for integration with Java; there are many add-on tools for Jess, referenced throughout the book. As with most rules engines, rules are specified as declarative patterns, not procedural code.

Jess in Action is well worth your time and attention, at the least for its exploration of rules, and at most for presenting a strong, flexible platform to tackle what is probably one of the uglier parts of your development: the sequencing and parameterization of business decisions. Although the list of Cons below is longer, they're just nit-picking; this is an excellent, entertaining, and productive read that will likely expand your programming horizons considerably.

Pros
* Clearly, concisely, and entertainingly written for Java programmers of any background
* A strong introduction to two important topics: rules and declarative programming style
* Well-chosen and developed working examples, each with a different design style
* The description of the author's unit test framework for rules in Appendix C is a nice touch

Cons
* Early discussion of Jess syntax focuses too much on Java-like procedural style
* More of a tutorial - not long enough to be a good reference (though that would probably require a detailed Jess Patterns book)
* Discussions of development methodology and knowledge engineering are unnecessary, as they're covered better elsewhere and a short summary adds little to the book
* There's no single list of rule and Jess-related links; references to tools and discussions are scattered throughout the book
* There are no general references to rules and rule-based systems for theory and background

Rating:
Summary: Excellent tutorial on using Jess
Review: Jess is a rule engine written in Java. This book is not about rules engines, although it does have a brief introduction to rules engines. This book is about Jess. In fact, this book is the book on Jess. If you are interested in learning what kind of problems Jess can be used to solve and how to use Jess to solve these problems then this book will answer your questions.

The book is basically divided into two sections. The first section is a tutorial on Jess. This section starts by showing how to install and configure Jess. The rest of this section covers the Jess syntax and demonstrates how to write rules for Jess. The tutorial is clearly written with some simple examples that do a good job of helping to make Jess understandable. The tutorial even shows how to do some optimizations for the rules that you write.

The rest of the book covers some fairly complicated applications written using Jess. The author refers to this section as a cookbook and the examples are complex enough and explained so well that it could easily serve this purpose. The best part of this section is that it will help someone who isn't familiar with rules engines develop ideas about how they might implement a rules engine to solve their own business requirements. The examples themselves cover integrating Jess with Java both in typical client based applications and J2EE web based applications.

If you are interested in using Jess as a possible solution to your business needs then this book is a virtual necessity. I couldn't imagine trying to use Jess without this book.

Rating:
Summary: Excellent tutorial on using Jess
Review: Jess is a rule engine written in Java. This book is not about rules engines, although it does have a brief introduction to rules engines. This book is about Jess. In fact, this book is the book on Jess. If you are interested in learning what kind of problems Jess can be used to solve and how to use Jess to solve these problems then this book will answer your questions.

The book is basically divided into two sections. The first section is a tutorial on Jess. This section starts by showing how to install and configure Jess. The rest of this section covers the Jess syntax and demonstrates how to write rules for Jess. The tutorial is clearly written with some simple examples that do a good job of helping to make Jess understandable. The tutorial even shows how to do some optimizations for the rules that you write.

The rest of the book covers some fairly complicated applications written using Jess. The author refers to this section as a cookbook and the examples are complex enough and explained so well that it could easily serve this purpose. The best part of this section is that it will help someone who isn't familiar with rules engines develop ideas about how they might implement a rules engine to solve their own business requirements. The examples themselves cover integrating Jess with Java both in typical client based applications and J2EE web based applications.

If you are interested in using Jess as a possible solution to your business needs then this book is a virtual necessity. I couldn't imagine trying to use Jess without this book.