DMN Method & Style: A Business Pracitioner's Guide to Decision Modeling

by Bruce Silver

The Decision Model and Notation (DMN) standard is transforming the practice of business decision management. Instead of "harvesting" business rules in text-based requirements documents handed off to programmers, business users themselves now can create true decision models that serve either as verifiable implementation requirements or complete, fully executable decision services. Completely revised from the original edition and updated to DMN 1.2, the book guides business users through the use of DMN, including creation of Decision Requirements Diagrams, decision tables, basic FEEL expressions, and invocation of more complex logic expressions created by others. It explains proper use of the DRD shapes and symbols, literal expressions in FEEL, and use of decision table analysis to ensure the decision logic is complete, consistent, and properly contracted and normalized. Even though the models are defined graphically in diagrams and tables, they are fully executable. The book shows how to execute decision logic directly in the modeling tool to test its correctness, and even how to deploy decision models as executable REST services in the cloud.

184 pages, Paperback

Published September 28, 2018

Reviews

[Peter De Kinder · Rating 3 out of 5]

The Decision Modeling Notation (DMN) is an industry standard (OMG) that was developed agnostic of existing and/or technologies. It allows for any vendor to adapt his product to adhere to this standard without restrictions, and serves as an executable syntax that can be easily integrated in BPMN and CMMN models in order to enrich them. The DMN specification is summed up by three features:
* Decision Tables: Tabular representations of logic that make up a decision rule.
* Decision Requirement Tables (DRD): Hierarchical ordering of multiple business rules to represent an end-to-end business decision.
* Friendly Enough Expression Language (FEEL): A pseudo-code expression language allowing for the introduction of functions (similar to those in for example Microsoft Excel).

Similar to his earlier work for BPMN, Bruce Silver published this book in 2016 to give DMN the same treatment: Explaining the different components that make up the notation, as well as showcase how to design different scenarios in a proper manner. As he exclaimed about BPMN Method &Style: “It’s not because you know all the words of a language that you can write a proper sentence”. Since then, a second edition was already released. But this review is still about the first edition.

The main focus for DMN is not to model strategic decisions (such as for example innovation management approaches), but rather the decisions (calculations, approvals, compliance checks…) that happen every day within the operational scope of an organization. These decisions are rooted in business considerations, not technical ones. These decisions are the ones typically written down in business requirements documents to be handed over to the implementation team who proceeds to code the resulting rules or input them in a Business Rules Engine (BRE).

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