Decision Model and Notation

Decision Model and Notation (DMN) is a standard published by the Object Management Group. It is a standard approach for describing and modeling repeatable decisions within organizations to ensure that decision models are interchangeable across organizations.

The DMN standard provides the industry with a modeling notation for decisions that will support decision management and business rules. The notation is designed to be readable by business and IT users alike. This enables various groups to effectively collaborate in defining a decision model:

The DMN standard is complementary to the BPMN standard. BPMN defines a special kind of activity, the Business Rule Task, which "provides a mechanism for the process to provide input to a business rule engine and to get the output of calculations that the business rule engine might provide".

DMN has been made a standard for Business Analysis according to BABOK v3.

The Decision Model and Notation (DMN) defines a Friendly Enough Expression Language (FEEL). It can be used to evaluate expressions in a decision table.

The standard identifies three main use cases for DMN

Using the DMN standard will improve business analysis and business process management, since

DMN has been designed to work with BPMN. Business process models can be simplified by moving process logic into decision services. Even though decision model notation is a separate domain within the OMG, the DMN spec provides an explicit way to connect to processes in BPMN. DMN provides a schema model in XML format that includes two connection points. First, there is an explicit list that denotes the processes and tasks that use the decisions. Next, DMN provides an input and output data type that implicitly corresponds to the rule activity that invokes the knowledge bases of the decision. In table 7 of the proposed OMG Specification, the class model for the decision defines the BPMN processes and tasks that require the decision to be made (usingProcesses and usingTasks).

As mentioned, BPMN is a related OMG Standard for process modeling. DMN was designed to complement BPMN and provides a separation of concerns between the decision and the process. The example here describes a BPMN process and DMN DRD (Decision Requirements Diagram) for onboarding a bank customer. Several decisions are modeled and these decisions will direct the processes response.

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