Drools vs Higson

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.

Higson is a business rules engine for managing product logic, pricing and decisions without coding, with a primary focus on insurance. It supports product configuration, underwriting and claims processing. Higson Studio lets business users edit rules through diagrams, decision tables and a tree structure, then run regression and mass tests using data imported from Excel. Version 4.3 includes a beta assistant that generates Groovy or Python logic from plain-language descriptions. Connections use REST and Java APIs, and supported SQL databases include Oracle, Microsoft SQL Server, PostgreSQL and MySQL. Rule snapshots can be exported to files and imported into other environments. Higson states that it is CREST certified and provides auditability, versioning and permissions scoped by business domain. Enterprise deployment is on-premise or in a private cloud; AWS Marketplace access is also offered. Enterprise costs $10,000 a year as a fixed annual fee, with no limit on users, rules or non-production environments. The Runtime AWS Marketplace listing offers a 7-day free trial that converts to a paid subscription unless canceled.