Recently I ordered the Gimbal proximity beacons and before getting my hands dirty with the iOS and Android SDKs I wanted to smoke test these tiny sweeties.

In the previous post I explained how to monitor JBoss AS 7 resources with JBison. I extended the sample web application called buffalo, to collect JMS, JVM and Http Connector metrics.

JBoss AS 7 metrics

The Developer’s Guide is the second book about Drools available from Packt. It nicely extends the Drools documentation showing a new point of view at almost all features.

Although it wasn’t always easy to follow I definitely recommend this book to developers who either are starting their journey with this rule engine or are already familiar with Drools. Examples are not trivial ‘hello world’ applications. Especially my favorite Drools Fusion chapter about complex event processing is built up on quite advanced rules for a fraud detection system.

When you build a package, all its assets are used to compile it. However you might want only a subset of your rules to go into a package. Moreover you might want to create different snapshots that include different set of rules. This article will show how to use the Selector feature available in Guvnor to build packages containing only these rules that satisfy user-defined constraints.

The Drools Pipeline is a great tool that allows to put facts into the rule engine from the outside world. Currently supported stores are JMS queues and topics and text files. The format of the payload is almost free to choose, since out of the box you can use JAXB, XStream and the powerful Smooks transformer to convert your data into facts, which the rule engine is able to consume.

This article explains how to use Pipelines.

It’s quite difficult to get started with Drools, especially if you don’t have experience in developing Java applications. You might imagine how steep the learning curve is for business analysts, who associates Java with an island or coffee. However this book is aimed at exactly this group of non-technical people, who have knowledge how business runs, but don’t know how or simply don’t have the tools to persist it and ‘transfer it to the world of computers’.

Drools 5 is available for download. The corresponding svn tag is http://anonsvn.labs.jboss.com/labs/jbossrules/tags/5.0.1.26597.FINAL/. You can read the announcement on the Drools blog.

FWIW, there’s also a book available released by Pack Publishing.

Guvnor is the business rules management system in Drools 5. When you deploy it out of the box, you get an unsecured web application that stores data in Jackrabbit’s embedded Derby database.

This article explains how to tune Guvnor deployed on JBoss Application Server 4.2.3. It’s available in English and German.

Drools evaluates facts which are present in the working memory. But it can also reason over data stored in a relational database. This can be achieved using for example a Hibernate Session to access a relational database and then creating a query. Objects in the resultset can be reasoned over the same way like facts in the working memory. An article, which describes this is available in English, German and Polsih.