An engine to execute decisions according to the DMN specification that is written in Scala. It uses the FEEL-Scala engine to evaluate FEEL expressions.
The DMN engine started as a slack time project, grown into a community-driven project, and is now officially maintained by Camunda. 🚀
It is integrated into Camunda 8 to evaluate DMN decisions.
Features: ✨
- Support for the latest version of DMN (Compliance Level 3)
- Pluggable auditing for history or validation
- Extensible by custom functions and object mappers
The coverage of the DMN standard is measured by the DMN TCK.
Please have a look at Camunda's DMN documentation and FEEL documentation. The documentation describes how to model DMN decisions and write FEEL expressions (e.g. data types, language constructs, builtin-functions, etc.).
Add the DMN engine as a dependency to your project.
<dependency>
<groupId>org.camunda.bpm.extension.dmn.scala</groupId>
<artifactId>dmn-engine</artifactId>
<version>${version}</version>
</dependency>The engine comes with a bunch of built-in functions which are defined by the DMN specification.
It allows you to define your own functions as FEEL expressions (using the keyword function) or as context entry element.
However, the engine provides also an SPI to add custom functions that are written in Scala / Java. The classes are loaded via Java's service loader mechanism. Please have a look at the documentation to see how to implement the SPI.
The engine has a transformer (aka ValueMapper) to transform the incoming variables into FEEL types and to transform the decision result back into regular Scala types.
If you need to transform custom types or change the result types then you can implement a SPI. The implementation is loaded via Java's service loader mechanism. Please have a look at the documentation to see how to implement the SPI.
Found a bug? Please report it using Github Issues.
Want to extend, improve or fix a bug? Pull Requests are very welcome.
Want to discuss something? Take a look at the Camunda Forum.