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DMN and TDM Compared – New Brief

by | Aug 16, 2017 | Business Rules, DMN

We are pleased to announce a new resource, DMN and TDM Compared, posted to our Briefs Page. The Decision Model and Notation (DMN) industry standard and The Decision Model (TDM) are decision modeling approaches that have both similarities and differences.

TDM is a proprietary approach established in 2009. Because it is well established and still practiced, many organizations want to understand the difference between TDM and the newer DMN industry standard. DMN is a standard published by the Object Management Group (OMG), the same standard body that publishes BPMN and UML.

TDM and DMN are both based on diagrams that show how decisions break down into (and require) sub-decisions and how these decisions use input data. There are minor notational differences but the commonalities are many.

From TDM to DMN
Experience with TDM is a strong advantage for any modeler building DMN decision models. The differences should not be underestimated, though, so TDM users should take note of several things when migrating to DMN.

  • Knowledge Sources in DMN are useful for showing how real-world knowledge such as policies or regulations drives the model.
  • Narrowly-scoped decisions that must be orchestrated by a process model should be replaced with a focus on a broad business decision.
  • Don’t assume that a decision must be automated or that it must be automated with business rules. Model all decisions first.
  • Input data in DMN works best when used to represent entities not, generally, individual fields. This keeps diagrams manageable.

To learn more, read the full brief here.


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