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Decision Model and Notation (DMN) in Drools

Decision Model and Notation (DMN) is a standard established by the Object Management Group (OMG) for describing and modeling operational decisions. DMN defines an XML schema that enables DMN models to be shared between DMN-compliant platforms and across organizations so that business analysts and business rules developers can collaborate in designing and implementing DMN decision services.

DMN facilitates the visualization and modeling of decisions through a standardized graphical notation. It allows business analysts and developers to collaborate effectively, translating business requirements into executable decision models.

Support Friendly Enough Expression Language (FEEL) to define decision logic in DMN

decision tables and other DMN boxed expressions

DMN model consists of:

  • Decision requirements diagrams (DRDs):

DRDs in DMN provide a graphical representation of the dependencies among decisions and input data.

  • Boxed expressions:

    • Decision Tables: Tabular format to define decision rules based on inputs and conditions.

    • Literal Expressions: Allows for the specification of simple expressions directly in the model.

    • Contexts: Define a named context for organizing related information or expressions.

    • Relations: Specify a table-like structure to represent relationships among elements.

    • Functions: Define reusable computations or operations.

    • Invocations: Call other decision services or models.

    • Lists: Collections of items that can be used as inputs or outputs in decision logic.

  • Including Models in DMN file:

In DMN, models can be integrated within a single DMN file to encapsulate complex decision-making processes:

  • PMML Models: Predictive Model Markup Language models can be included to leverage predictive analytics within decision logic, facilitating data-driven decisions.

  • Other DMN Models: Embedding other DMN models allows for modularization and reusability of decision logic across different decision- making contexts.

How DMN Works in Drools

Step 1: Model Decision Logic in DMN

  • Decision Requirements Diagram (DRD): Identify decisions and their relationships.

  • Decision Tables: Define decision rules based on inputs and conditions.

Step 2: Integrate DMN with Drools

  • Import DMN Model: Drools supports importing DMN files (XML format).

  • Execute DMN Models: Drools executes DMN models to evaluate decisions based on inputs.

Step 3: Deployment and Execution

  • Deployment: Deploy Drools with embedded DMN models in Java applications.

  • Execution: Use Drools APIs to invoke DMN models and get decision outcomes programmatically.


Integrating DMN with Drools provides organizations with a robust framework for managing and executing business rules effectively. It enhances agility, scalability, and collaboration between business stakeholders and IT teams, ultimately leading to

improved decision-making processes and operational efficiency.

As businesses continue to embrace digital transformation, leveraging DMN in Drools becomes increasingly pivotal for staying competitive in today's dynamic market landscape.

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