One Minute Bottom Line
|Recommended for developers working with Drools.
Drools, in my opinion, is not a hard technology to get into, especially if you have done some java development and have a decent idea about decisioning systems.
How the RETE algorithm works conceptually is usually a good enough starting point to design the rules (and accompanying code) effectively to get the job done.
However, Drools has various different sub-projects that are useful (e.g. Drools Fusion for Complex event processing, Drools Planner, Guvnor, jBPM5 etc) and this book does a very good job of introducing these projects and provides enough examples (and recipes) to get someone started. For example, I did not know that I could declare facts in the rules file itself (as opposed to a POJO or XML). I also did not know about the rules verifier which does an analysis of how the rules are written and points out redundancies and conflicts.
I found all the recipes to be useful (even though I do not plan on using them all) because they shed some light on Drools the technology and on best practices in using it.
Overall, I highly recommend this book for anyone planning to use Drools beyond a "Hello World" example. The broad coverage of topics and detailed (with working code) recipes definitely makes this book a good buy.