ANSWER

BPMN is used to define business processes as a sequence of activities. Gateways are used to show branching of different process paths.  For many years, analysts would clumsily model decision logic directly in business process models in an attempt to fully define process branching logic. This made process models messy.

DMN or Decision Modeling Notation was published in 2015 by the Object Management Group.  It's a graphical language for specifying business decisions.  DMNs primary purpose is to give analysts a tool for separating the business decision logic from the business process. This serves to greatly reduce the complexity of business process models and facilitate their readability. The encapsulation of business decision logic with DMN also allows the business process or business rules to change without impacting the other.

DMN is made up of 4 elements and 3 requirements as defined by specification published by the Object Management Group :

• Decision (element) - A decision denotes the act of determining an output from a number of inputs, using decision logic which may reference one or more business knowledge models. 

• Business Knowledge Model (element) - A business knowledge model denotes a function encapsulating business knowledge (e.g., as business rules, a decision table, or an analytic model).

• Input Data  (element) - An input data element denotes information used as an input by one or more decisions. When enclosed within a knowledge model, it denotes the parameters to the knowledge model. 

• Knowledge Source (element) - A knowledge source denotes an authority for a business knowledge model or decision

• Information Requirement - An information requirement denotes input data or a decision output being used as one of the inputs of a decision. 

• Knowledge Requirement - A knowledge requirement denotes the invocation of a business knowledge model. 

• Authority Requirement - An authority requirement denotes the dependence of a DRD element on another DRD element that acts as a source of guidance or knowledge.

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Chris Adams
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