Last session of day 1 of the BPM and Case Management Summit 2015 in DC, and Denis Gagne of Trisotech is up to talk about the three big standards: the Business Process Model and Notation (BPMN), the Case Management Model & Notation, and the Decision Model & Notation. BPMN has been around for a few years and is well-established — pretty much every business process modeling and automation vendor uses BPMN in some form in their process modelers, and it is OMG’s most-adopted standard — but CMMN and DMN are much newer and less widespread in the market. There are a few vendors offering CMMN modelers and even fewer offering DMN. There are two major benefits to standards such as BPMN, CMMN and DMN, in addition to the obvious benefit of providing an unambiguous format for modeling processes, management and decisions: they can be used to create models that can be interchanged between different vendors’ products; and they provide a common and readily-transferable “language” that is learned by analysts. This interchangeability, both of models and skills, means that organizations don’t need to be quite so worried about which modeling tool that they use, or the people that they hire to use it. Denis was at the Model Interchange Working Group (MIWG) OMG meeting in Berlin last week, where they showed all types of interchange for BPMN; with luck, we’ll be seeing the same activities for the other standards as they become widely adopted.
There are some grey areas about when to use BPMN versus CMMN, since both are (sort of) process-based. However, the main focus in BPMN is on activities within processes, whereas CMMN focuses on events that impact cases. He showed a chart comparing different facets of the three standards:
| BPMN | CMMN | DMN |
| Processes | Cases | Decisions |
| Activities | Events | Rules |
| Transitional | Contextual | Applied |
| Data | Information | Knowledge |
| Procedural | Declarative | Functional |
| Token | Event Condition Action (ECA) | First Order Logic (FOL) |
The interesting part (at least to me) comes when we look at the bridges between these standards: in BPMN, there is a business rule task that can call a decision in DMN; in CMMN, there is a process task that can call a process defined in BPMN. Trisotech’s version of all of these modelers (not yet in the standards, but count on Denis to get them in there) also provides for a case task type in BPMN that can call a CMMN case, and a decision task in CMMN that can call a DMN decision. There are some patterns to watch for when modeling that might indicate that you should be using another model type:
- In BPMN, if you have a lot of gateways expressing business logic, then consider moving the gateway logic to DMN
- In BPMN, if you have a lot of events especially boundary events, then consider encapsulating that portion into a CMMN case
- In BPMN, if you have a lot of ad hoc subprocesses, then consider using CMMN to allow for greater specification of the ad hoc activities
- In CMMN, if you have a lot of task interdependencies, consider using BPMN to replace the temporal dependencies with flow diagrams
The recognition and refactoring of these patterns is pretty critical for using the right model type, and are likely a place where a more trained technical analytical eye might be able to suggest improvements to models created by a less-technical analyst who isn’t familiar with all of the model types or how to think about this sort of decomposition and linking.
He demonstrated integration between the three model types using the Trisotech BPMN, CMMN and DMN modelers, where a decision task in the BPMN modeler can link directly to a decision within a model in the DMN modeler, and a case task in BPMN can link directly to a case model in the CMMN modeler. Nice integration, although it remains to be seen what analyst skill level is required to be able to model across all three types, or how to coordinate different analysts who might be modeling in only one of the three model types each, where the different models are loosely coupled with different authors.
Disclosure: I’m doing some internal work with Trisotech, which means that I have quite a bit of knowledge about their products, although I have not been compensated in any way for writing about them here on my blog.