Drools vs FlexRule Open

Drools is a free, open-source rule engine for building expert systems with forward- and backward-chaining inference. Its DMN engine supports Conformance level 3, covering the features in that standard, and can statically analyze decision tables for gaps and overlaps. For event processing, it reasons over streams using temporal operators, sliding windows, and event expiration. Developers can define rules in DRL text files alongside Java code, or use Excel decision tables, rule templates, or a Java executable model API. Rule units organize rules with typed containers for input data, and Kogito can generate REST endpoints from them. Drools rules can also be called by a BPMN business rule task in jBPM within the same service. Apache KIE states that the DMN engine passes 99.9% of DMN TCK tests as of version 10.2.0. The project is available for API, Linux, and self-hosted use at free. Getting started requires an IDE, JDK 21 or 17, and Maven 3.9 or later. Apache KIE is undergoing incubation and has not yet been fully endorsed by the ASF.

FlexRule Open combines data, business intelligence, rules and AI for enterprise decision intelligence in regulated environments. It supports Decision Model and Notation at Conformance Level 3 and Shared Data Model and Notation, and uses DecisionLang for declarative decision modeling and execution across multiple runtimes. The Open SDK lets technical teams extend DecisionLang with features, custom visuals and integration points without source-code access. Deployment can be in the cloud, on premises or at the edge, including embedded, browser, client and REST API service execution. Its RESTful API exposes configuration, permissions, security, deployment and decision execution. The authoring platform provides step-through debugging, breakpoints, execution-context inspection and no-code testing for rules, decisions, machine learning and other models. Users can manage and compare versions of artifacts, models and online services, and inspect change history. Connectors include databases, REST APIs, Gmail, Salesforce and Dynamics 365. Pricing is on request.