I am a freelance consultant, but I am acting today as a PhD student. The global context of my thesis is Enterprise Architecture (EA), which requires to model the Enterprise. As one aspect of EA is business process modeling, I am using BPMN from years, but this notation is not very appropriate to represent decision criteria: a cascade of nested gateways becomes quickly difficult to understand then to modify. So, when OMG published the first version 1.0 Beta of DMN specification in 2014 (at the beginning of my thesis), I found that DMN was a very interesting notation to model decision-making. I succeeded in developing my own DMN modeling tool, based on DMN metamodel, in using the Sirius plugin for Eclipse . But even the next “final” version 1.0 of DMN specification was not very accomplished, in fact.
The latest version 1.1 of DMN, published in June 2016, is quite good. In the meantime, software editors (at least twenty) have launched good modeling tools, as Signavio Decision Manager (free for Academics) used for this article. This Signavio tool was already able to generate specific DRL files for running DMN models on the BRMS Drools current version 6. In addition to the graphics, some editors added recently the capability to export DMN models (diagram & decision tables) into “DMN 1.1 XML” files, which are compliant with the DMN specification. And now, the good news is that BRMS like Drools (future version 7, already available in Beta version) are able to run theses DMN files for automating decision-making (a few lines of Java code are required to invoke theses high level DMN models).
This new approach of treating “DMN 1.1 XML” interchange model directly is better for tool independency and model portability. This is a short comparison between the former classic but specific solution and this new and generic solution, using the tool Signavio Decision Manager (latest version 10.13.0). MDA (Model Driven Architecture) and its three models CIM, PIM & PSM gives us the appropriate reading grid for this comparison:
| 3 MDA models | Description | Classic specific DMN solution from Signavio Decision Manager to BRMS Drools |
| CIM (Computation Independent Model) | Representation model for business, independent of computer considerations | DRD (Decision Requirements Diagram) + Decision Tables |
| PIM (Platform Independent Model) | Design model for computing, independent of the execution platform | û |
| PSM (Platform Specific Model) | Design model for computing, specific to the execution platform | DRL (Drools Rule Language) + DMN Formulae Java8-1.0-SNAPSHOT.jar |
So, in the classic but specific DMN solution, Signavio Decision Manager is able, from a business DMN model (DRD diagram and decision tables), to export a DRL file directly for a Drools rules engine. So, this solution skips the intermediate PIM level, that is not very compliant with MDA concept. Note that this DRL file needs a specific Signavio’s jar library with DMN formulae.
| 3 MDA models | Description | New generic DMN solution from Signavio Decision Manager(or other tools) to BRMS Drools (or other BRMS) |
| CIM (Computation Independent Model) | Representation model for business, independent of computer considerations | DRD (Decision Requirements Diagram) + Decision Tables |
| PIM (Platform Independent Model) | Design model for computing, independent of the execution platform | DMN 1.1 XML (interchange model) containing FEEL Expressions |
| PSM (Platform Specific Model) | Design model for computing, specific to the execution platform | û |
With the new generic DMN solution, Signavio Decision Manager is now able, from the same business DMN model (DRD diagram and decision tables), to export “DMN 1.1 XML” interchange model, which is a PIM, independent of the execution platform. As the future 7.0.0 version of Drools is able to interpret “DMN 1.1 XML” format directly, the last level PSM, specific to the execution platform, is not useful anymore.
The new generic DMN solution, without skipping PIM level, sounds definitely better than the specific one and is a good basis for automating decision-making. Another advantage is, as Signavio said, that this new approach using “DMN 1.1 XML” reduces the vendor lock-in.
| Reference: | DMN 1.1 XML: from modeling to automation with Drools 7.0 from our JCG partner Thierry Biard at the Drools & jBPM blog. |
