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DMN Expression Editor

The DMN Expression Editor is the window in which you will define, review and update the details of most of the different types of DMN element within your model. Primarily, it is used for editing the Value Expressions of Decision elements and BusinessKnowledgeModel (BKM) elements.

A different version of the DMN Expression Editor is displayed for each of the four types of value expression used by Decision elements and BKM elements. For BKM elements a second window tab is also presented, for defining the input and output parameters used in calling the BKM.

Two additional versions of the DMN Expression Editor also exist to support editing of ItemDefinitions and InputData elements.

The toolbar that is displayed and the layout of the window content are dependent upon the type of DMN element that is currently selected and, where applicable, the type of Value Expression being defined.

This image shows the version of the DMN Expression Editor used for defining a Decision Table. In this case, the underlying element is a BusinessKnowledgeModel, and so the decision logic is 'invoked' by other elements, with input and output passed via parameters.

Detailed explanations of the DMN Expression Editor's features for each element and expression type are provided in the Help topics that follow this one.

Access

Diagram

Double-click a DMN element on a diagram.

The DMN Expression editor window corresponding to the element and its expression type is displayed.

Value Expressions

Summarized in this table are four distinct types of value expression with references to the Help topics detailing each of them.

Type

Description

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

Literal Expression

A literal expression specifies the decision logic as a textual expression that describes how an output value is derived from its input values.  To support simulation and execution, the literal expression can use Javascript functions.

Literal Expression

Boxed Context

A boxed context is a collection of context entries, consisting of (name, value) pairs, each with a result value.

The context entries provide a means of decomposing a complex expression into a series of simple expressions, providing intermediate results that can be used in subsequent context entries.

Boxed Context

Invocation

An invocation calls on another model element (a BusinessKnowledgeModel or a Decision Service) to provide a decision result.  The invocation defines parameters that are passed into the 'invoked' element, providing context for evaluation of its decision logic.  The decision result is then passed back to the 'invoking' element.

Invocation

ItemDefinition and InputData Elements

Element

Description

See also

ItemDefinition

ItemDefinition elements are used to define data structures and optionally, to restrict the range of allowable values of the data.  ItemDefinitions can range from a simple single type through to a complex structured type.  ItemDefintions are used to specify the type of InputData elements as well as input parameters.

Item Definition

InputData

InputData elements are used to provide input to Decision elements.

The data type of an InputData element is defined using an ItemDefinition element.  Data Sets can also be defined as part of an ItemDefintion and an InputData element can then specify a Data Set to be used when running a simulation.

Input Data

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