Fundamental to creating Decision Models is the definition of the structure of data items used within the model. An ItemDefinition is used to define the structure of the input data 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.
ItemDefinition elements are created by dragging a icon from the DMN Toolbox onto a DMN diagram.
The core properties of an ItemDefinition element are accessed via the DMN Expression window.
To open the DMN Expression window for an ItemDefinition Element:
Simulate > Decision Analysis > DMN > DMN Expression, then select or create an ItemDefinition
Double-click on a DMN ItemDefinition
DMN Expression and Data set
The following image is an overview of the DMN Expression window showing a complex data item and the layout of the key fields used in the definition of the data. Included is a view of a Data Set defined using this ItemDefintion. A Data Set is an 'instance' of data conforming to an ItemDefinition, that contains a set of values to be used in the DMN simulation.
As ItemDefinitions are foundation elements in the model, it is recommended that they are 'validated' before going on to using them in the model. This will ensure that any issues are resolved early on in the process of creating a complex model.
For more details of setting up ItemDefinitions see the related topics below.