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Business Knowledge Model

A Business Knowledge Model (BKM) element represents a reusable piece of decision logic. Typically, it is connected to a Decision element that invokes the BKM and passes on a set of inputs. The BKM, using its internal logic, evaluates an output that is passed back to the Decision.

Unless a BKM is working on fixed values, it usually requires defining a set of input parameters, as well as the definition of an output. The parameters and the decision logic are defined using the DMN Expression window.

Inputs and Output

When used in a decision model, a BKM must be connected via a KnowledgeRequirement to a Decision or another BKM, through which it receives its inputs . The input parameters are defined using the icon. These can be set as a simple type or a complex type defined using an ItemDefinition. The naming of the input parameters influences the naming within the Value Expression.


A BKM output is via a KnowledgeRequirement which must be an input to a Decision or to another BKM. The output is defined using:

  • The icon for a Literal Expression
  • Output column(s) in the DMN Expression table for a Decision Table, Boxed Content and Invocation.

An output can be a simple type or a complex type defined using an ItemDefinition.

Value Expressions

To define a means for evaluating an output, based on the decision logic, a Business Knowledge Model (BKM) element contains a Value Expression. This is defined and edited using the DMN Expression window, which has four formats, the format being determined by the type of Value Expression that you want to use.

The BKM element can be set with these structures for the Value Expression. Each is shown in the model with an icon.



See also

Decision Table

A Decision Table is a tabular representation of a set of related input and output expressions, organized into rules indicating which output entry applies to a specific set of input entries.

Decision Table Decision Expression Editor

Literal Expression

A Literal Expression is the simplest form of DMN expression. It is commonly defined as a single-line statement or an if-else conditional block.

Literal Expression Decision Expression Editor


A Decision Invocation requires that a Business knowledge model element is referenced using a Knowledge Requirement connector. It simply contains the parameters that provide the context for the evaluating a business knowledge model.

Invocation Decision Expression Editor


A Boxed Context is a collection of context entries. Each context entry consists of a variable and an expression. The Context also has a result value.

Boxed Context Decision Expression Editor

Validation and Testing

To ensure a BKM element is able to produce a correct output it can be validated using the Validation icon .  A BKM can also be tested as a unit to ensure it is operative using the Simulation button. For more details see the Input Parameter Values for Simulation Help topic.

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