CMMN
An OMG standard for describing adaptive, loosely structured "case" processes, where tasks are activated by events and conditions.
Why CMMN was needed
For a long time BPMN was the universal tool, but practice showed that many real processes do not fit its frame. A legal case, a medical history, an incident investigation — each consists of tasks whose sequence is not fixed in advance. An experienced specialist decides what to do and when, based on the context and the rules.
For such loosely structured “cases” OMG developed a separate standard, CMMN, published in 2014.
The basic model
The central concept in CMMN is the case file. Inside it are:
- Tasks — things that can be done
- Stages — phases that group tasks
- Events — events that activate tasks
- Sentries — conditions for activating tasks
- Decorators — behavior modifiers (required, manual activation, repetition)
Unlike BPMN, tasks are not connected by sequence flows — they are available in parallel and are activated and completed by conditions.
When to use it
CMMN is best suited to:
- Legal processes (running a case)
- Medical processes (patient history)
- Incident investigation
- Claims handling
- Adaptive project management
The OMG triad
Together with BPMN and DMN, CMMN forms the “OMG triad” for modeling different aspects:
- BPMN — sequential, structured processes
- CMMN — adaptive, loosely structured cases
- DMN — models of business rules and decisions
In large projects all three standards are often used together.
Limitations
- Less tooling support than BPMN
- A high entry barrier due to the unfamiliar paradigm
- Fewer learning materials