Business Rule Task

Evaluates a DMN decision table and writes the output columns back as process variables. Combine with a Script Task or gateway conditions to branch on the decision result.

Properties

How It Works

1. Deploy your DMN XML via POST /api/v1/decisions
2. The decision’s id attribute becomes the Decision Ref
3. When a token reaches the business rule task, the engine evaluates the decision using current process variables as inputs
4. Output column values are written back as process variables with the same names as the output columns

XML Example

<bpmn:businessRuleTask id="classify_order" name="Classify Order">
  <bpmn:extensionElements>
    <conduit:decisionRef>order-classification</conduit:decisionRef>
  </bpmn:extensionElements>
  <bpmn:incoming>flow_to_classify</bpmn:incoming>
  <bpmn:outgoing>flow_to_route</bpmn:outgoing>
</bpmn:businessRuleTask>

Deploying a Decision

POST /api/v1/decisions
Content-Type: application/xml

<?xml version="1.0" encoding="UTF-8"?>
<definitions xmlns="https://www.omg.org/spec/DMN/20191111/MODEL/"
             id="order-decisions" name="Order Decisions"
             namespace="http://camunda.org/schema/1.0/dmn">
  <decision id="order-classification" name="Order Classification">
    <decisionTable hitPolicy="FIRST">
      <input id="amount_input" label="Amount">
        <inputExpression typeRef="number">
          <text>amount</text>
        </inputExpression>
      </input>
      <output id="tier_output" label="Tier" name="tier" typeRef="string"/>
      <rule id="rule1">
        <inputEntry><text>&gt; 1000</text></inputEntry>
        <outputEntry><text>"premium"</text></outputEntry>
      </rule>
      <rule id="rule2">
        <inputEntry><text></text></inputEntry>
        <outputEntry><text>"standard"</text></outputEntry>
      </rule>
    </decisionTable>
  </decision>
</definitions>

After this request, the variable tier is available to all subsequent elements in the instance.

See the Decision Tables docs for hit policies, FEEL input syntax, and full reference.