Model, Evaluate, and Deploy a Decision Requirements Graph

The visual representation of a Decision Requirements Graph (DRG) is called a Decision Requirements Diagram (DRD).

Switch from decision table to DRD

Open the existing Dish decision table and click View DRD to access the Decision Requirements Diagram view, which displays a single decision named Dish.

Set the name and the id of the DRD

Click the canvas and open the properties panel. Update the id to dinnerDecisions and the name to Dinner Decisions.

Create a new decision in the DRD

Select the decision icon from the palette to add a new decision. Name it Beverages and set its type to Decision Table using the wrench icon. Configure the id as beverages via the properties panel. Connect the Dish decision to Beverages to indicate that Dish is a required decision providing input for the beverages evaluation.

Configure the decision table and add the rules

Set up the Beverages decision table with:

Input: Dish (expression: desiredDish, type: string)
Input: Guests with children (expression: guestsWithChildren, type: boolean)
Output: Beverages (name: beverages, type: string)
Hit Policy: COLLECT (with LIST operator)

Save your changes and replace the DMN file in src/main/resources.

Catch up: get the sources of Step-5

git clone https://github.com/aseeflow/aseeflow-get-started-dmn.git
git checkout -f Step-5

Or download as a .zip.

Evaluate the decision

Extend the application class to evaluate the Beverages decision by adding a guestsWithChildren variable:

package org.camunda.bpm.getstarted.dmn;

@ProcessApplication("Dinner App DMN")
public class DinnerApplication extends ServletProcessApplication
{

  protected final static Logger LOGGER = Logger.getLogger(DinnerApplication.class.getName());

    @PostDeploy
    public void evaluateDecisionTable(ProcessEngine processEngine) {

      DecisionService decisionService = processEngine.getDecisionService();

      VariableMap variables = Variables.createVariables()
        .putValue("season", "Spring")
        .putValue("guestCount", 10)
        .putValue("guestsWithChildren", false);

      DmnDecisionTableResult dishDecisionResult = decisionService.evaluateDecisionTableByKey("dish", variables);
      String desiredDish = dishDecisionResult.getSingleEntry();

      LOGGER.log(Level.INFO, "\n\nDesired dish: {0}\n\n", desiredDish);

      DmnDecisionTableResult beveragesDecisionResult = decisionService.evaluateDecisionTableByKey("beverages", variables);
      List<Object> beverages = beveragesDecisionResult.collectEntries("beverages");

      LOGGER.log(Level.INFO, "\n\nDesired beverages: {0}\n\n", beverages);
    }

}

Catch up: get the sources of Step-6

git clone https://github.com/aseeflow/aseeflow-get-started-dmn.git
git checkout -f Step-6

Or download as a .zip.

Build and deploy the web application

Build with Maven and replace dinner-dmn-0.1.0-SNAPSHOT.war in $ASEEFLOW_HOME/server/apache-tomcat/webapps. Check the Tomcat log for successful deployment indicators:

INFO org.camunda.commons.logging.BaseLogger.logInfo
ENGINE-07015 Detected @ProcessApplication class 'org.camunda.bpm.getstarted.dish.DishApplication'
INFO org.camunda.commons.logging.BaseLogger.logInfo
ENGINE-08024 Found processes.xml file at ../webapps/dinner-dmn-0.1.0-SNAPSHOT/WEB-INF/classes/META-INF/processes.xml
INFO org.camunda.commons.logging.BaseLogger.logInfo
ENGINE-08023 Deployment summary for process archive 'dinner-dmn':

        dinnerDecisions.dmn

INFO org.camunda.bpm.getstarted.dmn.DinnerApplication.evaluateDecisionTable

Desired dish: Stew

INFO org.camunda.bpm.getstarted.dmn.DinnerApplication.evaluateDecisionTable

Desired beverages: [Guiness, Water]

INFO org.camunda.commons.logging.BaseLogger.logInfo
ENGINE-08050 Process application Dinner App DMN successfully deployed

Verify the evaluation with Cockpit

Open Cockpit and navigate to the Decisions section.

Click the Beverages decision and select an id to review the historic evaluation data.

Verify that both rules matched, producing beverages outputs of Guiness and Water. Note that the Dish decision evaluates as part of the Beverages evaluation, providing Stew for the desiredDish input.

Next steps

Learn more about DRGs in the DMN Reference
Explore the full Decision Engine documentation

​Switch from decision table to DRD

​Set the name and the id of the DRD

​Create a new decision in the DRD

​Configure the decision table and add the rules

​Evaluate the decision

​Build and deploy the web application

​Verify the evaluation with Cockpit

​Next steps

Switch from decision table to DRD

Set the name and the id of the DRD

Create a new decision in the DRD

Configure the decision table and add the rules

Evaluate the decision

Build and deploy the web application

Verify the evaluation with Cockpit

Next steps