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Decision

A Decision element is used to evaluate an output based on one or more inputs. The logic that determines the output is either defined within that Decision element or it invokes the decision logic contained in a Business Knowledge Model that is connected to the Decision.

Inputs

A Decision can have any number of inputs, including the option to define the input values in the element. The most common input is to use an Input Data Element.

Output

A decision can have zero or one output. The output can be a complex data set.

Value Expressions

The output of a Decision element is determined using a Value Expression.  The Value Expression contains the element's decision logic and can take one of four forms:  Decision Table, Literal Expression, Invocation or Boxed Context.  Value Expressions are defined and edited using the DMN Expression editor, which displays one of four formats according to the type of expression being used. 

When displayed on a diagram, the Decision element shows an icon in the top-right corner that indicates which type of value expression it is using.

Type

Description

See also

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 DMN 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 DMN Expression Editor

Invocation

A Decision Invocation requires that a Business Knowledge Model element is referenced using a Knowledge Requirement connector. The Decision element simply contains the parameters that provide the context for evaluating the Business Knowledge Model (BKM). Part or all of  the result returned from the BKM can be set to be passed as the output of the Decision.

Invocation DMN Expression Editor

Boxed Context

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 DMN Expression Editor

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