Last Year

Drools Reactive Messaging processing

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The latest Drools 8.31.0.Final comes with a Reactive Messaging example, which demonstrates reactively consuming messages from a Kafka topic, firing rules and then sending result messages to another Kafka topic. You can find it in This blog post explains how it works. How To Run the Example Clone drools repository Go to the exampleRead more →

Drools trouble-shooting : Memory issues

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Memory issues are another frequent topic in Drools trouble-shooting. This article will explain how to solve issues categorized in 3 types. Long term memory leak while using Drools applications The word "Memory leak" is typically used for the situation where a JVM triggers Full GCs but the footprint is constantly increasing. In this case, let’sRead more →

Upgrade Drools version

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We sometimes see questions regarding Drools version upgrade. Most of those questions are about how to change the old API usage in Drools 5 or 6. In this article, I’m going to guide how to change your code to work with the latest Drools version (7.70.0.Final as of now). API If you are using oldRead more →

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Drools basic examples

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Drools community discusses various usage, issues and questions on google group ( , and zulip chat ( daily basis. When we discuss the usage of a specific feature or syntax (for example, "accumulate"), our documentation ( is the best resource but there may be cases where users stumble when they try a little different thing fromRead more →

Rule Impact Analysis

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After you develop rules and put the system into production, you will need tomaintain the rules to keep up with business requirements. Basicallytests should ensure the correctness and integrity of the updatedrules, but while you work on updating the rules, you might want toknow the "impact" of your changes. Rule impact analysis feature helps you.Read more →