What is Decision Model and Notation

Decision Model and Notation (DMN) is a standard published and managed by the Object Management Group (OMG). It provides a standard approach for describing, modeling, simulating, reusing and implementing repeatable decisions within an organization or an initiative. It is also intended to facilitate the sharing and interchange of Decision models between organizations.

The modeling notation consists of a visual grammar that allows decisions and business rules to be documented in a way that makes them readable by both business and technical audiences, thus ensuring that decisions and rules are not misinterpreted. The resulting Decision model also provides a definition of how to evaluate the logic of decisions defined in Decision Tables, using the Friendly Enough Expression Language (FEEL).

The DMN defines two levels of the language, which neatly align with organizational roles:

Requirements Level

Aligns with the business people who devise, analyze and define the decision rules. This provides a mechanism for the people who own the business to model the rules without the need for technical knowledge of how they are implemented.

Logic Level

Aligns with implementation teams, who augment the definitions to include decision logic in the form of Decision Tables that can be maintained by the business staff, or expression logic managed by technical staff.

In this example we see that the main Decision has two inputs from other Decision Tables that are processed first and that contribute to the overall decision about whether the application will be accepted or not. This table shows the Risk Assessment Decision Table.