Setting up a Simulation

Setting up a simulation is straightforward; Enterprise Architect provides an Artifact that can be simply added to any Decision Requirements diagram to begin the process of configuring the Decision Model. The DMN Simulation Configuration element, available from the DMN Toolbox page, has the abbreviated name DMNSimConfiguration.

To start the process simply drag-and-drop a DMNSimConfiguration element onto a Decision Requirements diagram and then double click the element to launch the Simulation window.

The Simulation window does most of the heavy lifting and there are only a small number of things that you need to do to configure the simulation. When the window opens it will be preloaded with all possible Decisions or Business Knowledge Models that can act as starting points for the simulation; these are provided in a drop-down list from which you can select any one as the basis for the simulation. There are only two things that must be configured, and these are set to their defaults when you open the window - the selected decision defaults to the highest in the hierarchy, and the data sets are preset to their defaults. If you decide to work with the defaults, you can simply run the  simulation without having to configure anything.

It would, however, be considered good practice at this point to run a validation check which would be run for all Decisions and Business Knowledge Models (BKMs) in the diagram. This option is available from the Simulation window toolbar and allows you to check that there are no syntactic or semantic (overlaps and gaps) in the expressions before running the simulation. If the validation results in errors it would be judicious to correct the problems before running the simulation.

The next step is the selection of the Input Data required for participant decisions and BKMs. This facility is one of the reasons Enterprise Architect is a market leader in this field, as it allows a modeler or a team to run the simulations with different input data that can be saved as a set and reused to visualize how the Decision Model will respond in different contexts.

A data set that has been predefined and given a meaningful name can be selected for each Input Data element. The list of data sets is available from a drop-down menu visible to the right of the Input Data item in the list.  Selecting an item from the list tells the simulation engine that this is the data you want to use for the particular Input Data item and this will be displayed when you run a simulation.

With these set you can run the simulation and view the outputs. We will explore the features available for simulation in the next topic.

Finding Simulation Configurations

There might be occasions where you have forgotten the location of a Decision model that you have previously set up for simulation; in this situation Enterprise Architect provides a useful feature that allows you to locate the Simulation Artifact and therefore the diagram that contains it. The facility is available from this location:

Simulate > Decision Analysis > DMN  > Find DMN Configuration Artifacts.

This will return a list of Simulation Artifacts; using the context (right-click) menu you can locate the diagram that contains the element, and then by double clicking on the DMNSimConfiguration element in the diagram the Simulation will be launched.